1-CMV Retinitis
Cytomegalovirus (CMV) retinitis is a sight-threatening disease frequently associated with Acquired Immunodeficiency Syndrome (AIDS). In the past, about a quarter of active AIDS patients developed CMV retinitis.
However, this figure is dropping dramatically, thanks to a potent combination of drugs used to treat AIDS that help restore function of the immune system. In recent years, these drugs have helped decrease presence of CMV retinitis in late-stage AIDS by more than 80 percent.*
CMV Retinitis Symptoms and Signs
When CMV invades the retina, it begins to compromise the light-sensitive receptors that enable us to see. This does not cause any pain, but you may see floaters or small specks and experience reduced visual acuity (blurry vision) or decreased peripheral vision.
Light flashes and sudden vision loss also can occur. The disease usually starts in one eye but often involves both eyes. If left untreated, CMV retinitis can cause a detached retina and blindness in just two to six months.
AIDS patients sometimes also experience changes to the retina and optic nerve without clear signs of CMV retinitis.
What Causes CMV Retinitis?
CMV retinitis is caused by the cytomegalovirus, a very common virus belonging to the herpes family. About 80 percent of adults harbor antibodies to CMV, which indicates that they have been infected with the virus but their bodies have successfully fought it off.
For people with AIDS, the difference is that their weakened or non-functioning immune system cannot stave off this virus. Other people with a weakened or suppressed immune system, such as those undergoing chemotherapy or a bone marrow transplant, also are at risk. CMV retinitis occurs much less frequently in this group of patients than in the AIDS population.
Stopping vision loss caused by CMV retinitis involves understanding mechanisms of cell death that accompany an infection, Medical College of Georgia School of Medicine virologist and immunologist Sally Atherton, PhD, said in early 2009.
Under a $1.3 million National Eye Institute grant, Dr. Atherton and other researchers are studying how CMV retinitis progresses.
"Normally the retina is neatly stratified. What happens with CMV retinitis is, you get an infection in the most external part of the retina," Dr. Atherton said.
She explained that the virus likely is present but latent on the outer layer of the retina before CMV retinitis develops. Once activated, however, the virus starts to trigger cell death that spreads into deeper layers.
"Unchecked, it can ruin your vision — especially if it affects the macula, or central part of the retina responsible for highest visual acuity," Dr. Atherton said.
The AIDS Toll
According to Centers for Disease Control and Prevention (CDC) statistics released in December 2008, 1.1 million people in the United States are living with HIV/AIDS. These numbers have stabilized in recent years, due largely to public education and prevention efforts.
But with more effective medical intervention, more people infected with HIV are living longer. This means that those with HIV must be vigilant about observing safe sex practices to avoid spreading the disease to others.
In 2004, the CDC estimated that African-Americans accounted for half of the cases diagnosed, even though this group was only 12 percent of the U.S. population.
Non-whites also significantly were more at risk of developing vision loss from CMV retinitis related to AIDS. This finding indicates lack of early treatment and ongoing inequities in the U.S. health system, according to a four-year, Los Angeles County-based study reported in the January 2008 issue of American Journal of Ophthalmology.
Worldwide, the numbers of people living with HIV are declining. In November 2006, the World Health Organization (WHO) estimated that 39.5 million people were living with HIV. In a December 2008 report, WHO said the worldwide number of people with HIV had fallen to 33 million, with 7,500 new infections reported daily.
Most worldwide HIV cases are found in sub-Saharan Africa, where access to treatment is extremely limited. — L.S. & M.H.
CMV Retinitis Treatment
If you have active AIDS and are experiencing visual symptoms, you should see a retina specialist immediately. A person newly diagnosed with CMV retinitis can expect to visit the specialist every two to four weeks.
Once the disease is controlled, those visits may be with your regular eye doctor every three to six months, according to Robert Kalayjian, MD, an infectious disease specialist at Case Western Reserve University School of Medicine in Cleveland.
Drugs for CMV Retinitis. The anti-viral drugs commonly used to treat CMV retinitis are ganciclovir (Cytovene), foscarnet (Foscavir) and cidofovir (Vistide). They can slow down the progression of CMV, but they can't cure it.
Like many drugs, these treatments can cause unpleasant or serious side effects. Until recently, all three were given intravenously, and ganciclovir and foscarnet required an indwelling catheter placed in the chest for daily infusions.
Now, ganciclovir is available in pill form (used following two weeks of intravenous infusion). It also is administered in an intravitreal implant called Vitrasert (Bausch & Lomb).
The implant is inserted inside the eye in the vitreous gel cavity. During a five-to-eight-month period, Vitrasert slowly releases a precise amount of ganciclovir. The medication penetrates directly into the vitreous and the retina, to the source of the CMV retinitis.
Unlike intravenous or oral ganciclovir, Vitrasert typically does not cause systemic side effects such as nausea. Vitrasert is implanted as an outpatient procedure, not requiring hospitalization. The implantation usually takes less than an hour and requires only local anesthesia.
Drugs for HIV. The biggest treatment breakthrough is highly active antiretroviral therapy (HAART), a combination of drugs that suppress the human immunodeficiency virus (HIV), also known as the AIDS virus. HAART allows the immune system of an AIDS patient to recover and fight off infections such as CMV retinitis.
Your doctor may suggest you continue taking anti-CMV drugs for the first three or more months of HAART
A few patients on HAART develop a serious, sight-threatening inflammation inside the eye called immune recovery uveitis. Causes of the inflammation are unclear and require further study.
Also, depending on individual variables, patients with CMV retinitis and who are undergoing various drug treatments can be at higher risk for vision problems such as retinal detachment and cataracts.
Judith Lee also contributed to this article.
2-Diabetic Retinopathy
If you have diabetes, you probably know that your body can't use or store sugar properly. When your blood sugar gets too high, it can damage the blood vessels in your eyes. This damage may lead to diabetic retinopathy. In fact, the longer someone has diabetes, the more likely he is to have retinopathy.
In later stages, the disease may lead to new blood vessel growth over the retina. The new blood vessels can cause scar tissue to develop, which can pull the retina away from the back of the eye. This is known as retinal detachment, and it can lead to blindness if untreated.
In addition, abnormal blood vessels can grow on the iris, which can lead to glaucoma.
People with diabetes are 25 times more likely to lose vision than those who are not diabetic, according to the American Academy of Ophthalmology.
Diabetic Retinopathy Symptoms and Signs
Everyone who has diabetes is at risk for developing diabetic retinopathy, but not all diabetics do develop it. In its early stages, you may not notice any change in your vision, but it can lead to the later, sight-threatening form of the disease.
Floaters can be a sign of diabetic retinopathy. Sometimes difficulty reading or doing close work can indicate that fluid is collecting in the macula, the most light-sensitive part of the retina. This fluid build-up is called macular edema.
Another sign is double vision, which occurs when the nerves controlling the eye muscles are affected. If you experience any of these signs, see your eye doctor immediately. Otherwise, diabetics should see their eye doctor at least once a year for a dilated eye exam.
Your eye doctor may diagnose retinopathy using a special test called fluorescein angiography. In this test, dye is injected into the body and then gradually appears within the retina due to blood flow. Your eye care practitioner will photograph the retina with the illuminated dye. Evaluating these pictures tells your doctor how far the disease has progressed.
What Causes Diabetic Retinopathy?
Changes in blood-sugar levels increase your risk of diabetic retinopathy, as does long-term diabetes. Generally, diabetics don't develop diabetic retinopathy until they have had diabetes for at least 10 years, but it is not wise to wait that long to have an eye exam. As soon as you've been diagnosed with diabetes, you need to have a dilated eye exam at least once a year.
High blood sugar can damage blood vessels in the retina, and when they are damaged, they can leak fluid or bleed. This causes the retina to swell and form deposits. This is an early form of diabetic retinopathy called nonproliferative or background retinopathy.
In a later stage, called proliferative retinopathy, new blood vessels grow on the surface of the retina. These new blood vessels can lead to serious vision problems because they can break and bleed into the vitreous, the clear, jelly-like substance that fills the center of the eye. Proliferative retinopathy is a much more serious form of the disease and can lead to blindness.
Fortunately, you can significantly reduce your risk of developing diabetic retinopathy by using common sense and taking good care of yourself.
• Keep your blood sugar under good control.
• Monitor your blood pressure and keep it under good control, or seek appropriate care.
• Maintain a healthy diet.
• Exercise regularly.
• Follow your doctor's instructions to the letter.
Diabetic Retinopathy Treatment
According to the American Academy of Ophthalmology, 95 percent of those with significant diabetic retinopathy can avoid substantial vision loss if they are treated in time. The possibility of early detection is why it is so important for diabetics to have a dilated eye exam at least once a year.
Diabetic retinopathy can be treated with laser photocoagulation to seal off leaking blood vessels and destroy new growth. Laser photocoagulation doesn't cause pain, because the retina does not contain nerve endings.
In some patients, blood leaks into the vitreous humor and clouds vision. The eye doctor may choose to simply wait to see if the clouding will dissipate on its own, a period called "watchful waiting." A procedure called a vitrectomy removes blood that has leaked into the vitreous humor. The body gradually replaces lost vitreous humor, and vision usually improves.
If diabetic retinopathy has caused your body to form a cataract, it can be corrected surgically. Patients who have developed glaucoma should see a glaucoma specialist.
Small studies using investigational treatments for diabetic retinopathy have demonstrated significant vision improvement for individuals who are in early stages of the disease. Two treatments that are closely related, Lucentis and Avastin, may be able to stop or reverse vision loss, similar to very promising results that have been reported when the two drugs have been used as treatments for macular degeneration.
Diabetic Retinopathy News
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Intensive blood sugar control and combination lipid therapy can slow diabetic retonpathy progression. >>
Lucentis Injections Plus Laser Therapy Improve Vision
In a study of diabetes-associated macular swelling, eye injections of Lucentis, often combined with laser therapy, showed better results than lasers alone. >>
Eye Exam Assistance Program
If you think you can't afford an eye exam but are diabetic, a U.S. citizen, 65 or older and without eye care insurance through an HMO or the VAF, please call 1-800-272-EYES (3937). You may be eligible for a referral for eye exams and up to one year of treatment at no out-of-pocket cost.
Medicare and/or other insurance reimbursement is accepted by the volunteer ophthalmologists as payment in full.
Called the Diabetes EyeCare Program, it is offered by EyeCare America, the public service foundation of the American Academy of Ophthalmology.
3-Eye Herpes
Caused by the type 1 herpes simplex virus, eye herpes (ocular herpes) is a common, recurrent viral infection affecting the eyes. This type of herpes virus can cause inflammation and scarring of the cornea that sometimes is referred to as a cold sore on the eye. Herpes of the eye can be transmitted through close contact with an infected person whose virus is active.
The National Eye Institute (NEI) says an estimated 400,000 Americans have experienced some form of ocular herpes, with close to 50,000 new and recurring cases occurring each year.
Forms of Eye Herpes
Ranging from a simple infection to a condition that can possibly cause blindness, there are several forms of eye herpes:
• Herpes keratitis is the most common form of eye herpes and is a viral corneal infection. Ocular herpes in this form generally affects only the top layer, or the epithelium, of the cornea, and usually heals without scarring.
• Stromal keratitis occurs when the infection goes deeper into the layers of the cornea. This can lead to scarring, loss of vision and, occasionally, blindness. Stromal keratitis is thought to be caused by a late immune response to the original infection. Although the condition is rare, the NEI reports that stromal keratitis is the leading cause of corneal scarring that subsequently causes blindness in the United States.
• Iridocyclitis is a serious form of eye herpes where the iris and surrounding tissues inside the eye become inflamed, causing severe sensitivity to light, blurred vision, pain and redness. Iridocyclitis is a type of uveitis that affects the more frontal portions of the inside of the eye.
When this infection occurs in the retina or the inside lining of the back of the eye, it is known as herpes retinitis.
Eye Herpes Symptoms and Signs
Various signs and symptoms are associated with an ocular herpes outbreak. You may experience inflammation of the cornea, which can cause an irritation or sudden and severe ocular pain. Also, the cornea can become cloudy, leading to blurry vision.
Other characteristics of eye herpes include:
• Swelling around the eyes
• Tearing
• Recurrent eye infections
• Irritation
• Foreign body sensation
• Eye redness
• Eye sores
• Watery discharge
• Sensitivity to light
Due to these numerous symptoms, your eye doctor may overlook an initial diagnosis of ocular herpes in its very early stages.
What Causes Eye Herpes?
Eye herpes is transmitted through contact with another person who is having an outbreak, or through self contact and contamination during an active herpes infection (such as a cold sore of the lip).
The herpes simplex virus enters the body through the nose or mouth and travels into the nerves, where it may be inactive. The virus can remain dormant for years and may never wake up. The exact cause of an outbreak is unknown, but stress-related factors such as fever, sunburn, major dental or surgical procedures and trauma are often associated with incidents.
Once the initial outbreak occurs, the NEI says untreated eye herpes has about a 40-50 percent chance of returning. There is no specific time frame for ocular herpes to reappear; it could be several weeks or even several years following the original occurrence. Although symptoms usually present themselves in only one eye, the virus possibly could affect the other eye as well.
Eye Herpes Treatment
Treatment for eye herpes depends on where the infection is located in the eye — in the corneal epithelium, corneal stroma, iris, retina, etc. Some ocular herpes treatments could aggravate the outbreak and therefore should be considered on a case-by-case basis.
If the corneal infection is only superficial, it can normally be alleviated by using antiviral eye drops or ointments, or oral antiviral pills.
Zirgan (Sirion Therapeutics, Tampa, Fla.) was approved by the FDA in late 2009 as a topical antiviral treatment for eye herpes. The treatment (ganciclovir ophthalmic gel, 0.15 percent), which became commercially available in the United States in late April 2010, involves instilling eye drops five times daily until the related corneal ulcer heals.
You should not wear contact lenses while undergoing treatment with Zirgan, which is marketed in Europe as Virgan.
An eye doctor may treat eye herpes by scraping away the infected corneal epithelial cells with a cotton swab or corneal "spatula" instrument. This is called debridement. Following debridement, a patch or soft contact lens might be needed to help the cornea to heal.
Steroid drops can help decrease inflammation and prevent corneal scarring when the infection appears deeper in the corneal layers. Steroid drops are almost always used in conjunction with and simultaneously with antiviral drops.
Steroid drops decrease the effectiveness of the eye's immune system. Therefore, people with a history of ocular herpes should use only a steroid drop specifically prescribed by their eye doctor.
Steroid drops have been known to cause a recurrent eye herpes infection in susceptible patients. Also, an antibiotic eye drop along with a therapeutic contact lens may be used to prevent a secondary bacterial infection while the herpes eye infection is being treated.
Surgery is required if scarring occurs in the cornea and the treatments including the steroids do not help clear the center of the cornea. In cases where corneal scarring is permanent, a corneal transplant may restore vision.
Although eye herpes has no cure, treatment can help control outbreaks. Studies are underway to determine better methods for managing the disease.
4-Glaucoma
Glaucoma refers to a category of eye disorders often associated with a dangerous buildup of internal eye pressure (intraocular pressure or IOP), which can damage the eye's optic nerve that transmits visual information to the brain.
With untreated or uncontrolled glaucoma, you might eventually notice decreased ability to see at the edges of your vision (peripheral vision). Progressive eye damage could then lead to blindness.
In fact, glaucoma creates at least some vision loss in more than half of the approximately 2.5 million Americans estimated to have the eye disease and is the second leading cause of blindness.
Glaucoma Symptoms
Glaucoma often is called the "silent thief of sight," because most types typically cause no pain and produce no symptoms until noticeable vision loss occurs.
For this reason, glaucoma often progresses undetected until the optic nerve already has been irreversibly damaged, with varying degrees of permanent vision loss.
But with acute angle-closure glaucoma, symptoms that occur suddenly can include blurry vision, halos around lights, intense eye pain, nausea and vomiting. If you have these symptoms, make sure you see an eye care practitioner or visit the emergency room immediately so steps can be taken to prevent permanent vision loss.
Diagnosis, Screening and Tests for Glaucoma
During routine eye exams, a tonometer is used to measure your intraocular pressure, or IOP. Your eye typically is numbed with eye drops, and a small probe gently rests against your eye's surface. Other tonometers send a puff of air onto your eye's surface.
An abnormally high IOP reading indicates a problem with the amount of fluid (aqueous humor) in the eye. Either the eye is producing too much fluid, or it's not draining properly.
Normally, IOP should be below 21 mmHg (millimeters of mercury) — a unit of measurement based on how much force is exerted within a certain defined area.
If your IOP is higher than 30 mmHg, your risk of glaucoma damage is 40 times greater than someone with an IOP of 15 mmHG or lower.* This is why glaucoma treatments such as eye drops are designed to keep IOP low.
Other methods of monitoring glaucoma involve the use of sophisticated imaging technology — such as scanning laser polarimetry (SLP), optical coherence tomography (OCT) and confocal scanning laser ophthalmoscopy — to create baseline images and measurements of the eye's optic nerve and internal structures.
Then, at specified intervals, additional images and measurements are taken to make sure no changes have occurred over time that might indicate progressive glaucoma damage.
Visual field testing is a way for your eye doctor to determine if you are experiencing vision loss from glaucoma. Visual field testing involves staring straight ahead into a machine and clicking a button when you notice a blinking light in your peripheral vision. The visual field test may be repeated at regular intervals to make sure you are not developing blind spots from damage to the optic nerve or to determine the extent or progression of vision loss from glaucoma.
Gonioscopy also may be performed to make sure the aqueous humor (or "aqueous") can drain freely from the eye. In gonioscopy, special lenses are used with a biomicroscope to enable your eye doctor to see the structure inside the eye (called the drainage angle) that controls the outflow of aqueous and thereby affects intraocular pressure. Ultrasound biomicroscopy is another technique that may be used to evaluate the drainage angle.
Types of Glaucoma
The two major types of glaucoma are chronic or primary open-angle glaucoma (POAG) and acute angle-closure glaucoma. The "angle" in both cases refers to the drainage angle inside the eye that controls aqueous outflow. Other variations include normal-tension glaucoma, pigmentary glaucoma, secondary glaucoma and congenital glaucoma.
Your eye pressure (intraocular pressure) will be measured with a tonometer. Some tonometers blow a puff of air onto your eye's surface. Others rest gently against the surface of your eye, which will be numbed with eye drops. [Photo: National Eye Institute, National Institutes of Health]
Glaucoma can be very destructive to your vision; in fact, it's the second-leading cause of blindness in the United States.
Primary open-angle glaucoma (POAG). About half of Americans with chronic glaucoma don't know they have it. This common type of glaucoma gradually reduces your peripheral vision without other symptoms. By the time you notice it, permanent damage already has occurred.
If your IOP remains high, the destruction caused by POAG can progress until tunnel vision develops, and you will be able to see only objects that are straight ahead.
Angle-closure glaucoma. Angle-closure or narrow-angle glaucoma produces sudden symptoms such as eye pain, headaches, halos around lights, dilated pupils, vision loss, red eyes, nausea and vomiting.
These signs may last for a few hours, then return again for another round. Each attack takes with it part of your field of vision.
Normal-tension glaucoma. Like POAG, normal-tension glaucoma (also termed normal-pressure glaucoma, low-tension glaucoma or low-pressure glaucoma) is an open-angle type of glaucoma that can cause visual field loss due to optic nerve damage. But in normal-tension glaucoma, the eye's IOP remains in the normal range.
Also, pain is unlikely and permanent damage to the eye's optic nerve may not be noticed until symptoms such as tunnel vision occur.
The cause of normal-tension glaucoma is not known. But many doctors believe it is related to poor blood flow to the optic nerve. Normal-tension glaucoma is more common in those who are Japanese, are female and/or have a history of vascular disease.
Pigmentary glaucoma. This rare form of glaucoma is caused by pigment deposited from the iris that clogs the drainage angle, preventing aqueous humor from leaving the eye. Over time, the inflammatory response to the blocked angle damages the drainage system.
You are unlikely to notice any symptoms with pigmentary glaucoma, though some pain and blurry vision may occur after exercise. Pigmentary glaucoma affects mostly white males in their mid-30s to mid-40s.
Secondary glaucoma. Symptoms of chronic glaucoma following an eye injury could indicate secondary glaucoma, which also may develop with presence of eye infection, inflammation, a tumor or an enlarged cataract.
Congenital glaucoma. This inherited form of glaucoma is present at birth, with 80 percent of cases diagnosed by age one. These children are born with narrow angles or some other defect in the drainage system of the eye.
It's difficult to spot signs of congenital glaucoma, because children are too young to understand what is happening to them. If you notice a cloudy, white, hazy, enlarged or protruding eye in your child, consult your eye doctor. Congenital glaucoma typically occurs more in boys than in girls.
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Glaucoma Treatments
Treatment can involve glaucoma surgery, lasers or medication, depending on the severity. Eye drops with medication aimed at lowering IOP usually are tried first to control glaucoma.
Because glaucoma often is painless, people may become careless about strict use of eye drops that can control eye pressure and help prevent permanent eye damage.
In fact, non-compliance with a program of prescribed glaucoma medication is a major reason for blindness caused by glaucoma.
If you find that the eye drops you are using for glaucoma are uncomfortable or inconvenient, never discontinue them without first consulting your eye doctor about a possible alternative therapy.
5-Keratoconus
Keratoconus is a progressive eye disease in which the normally round cornea thins and begins to bulge into a cone-like shape. This cone shape deflects light as it enters the eye on its way to the light-sensitive retina, causing distorted vision.
Keratoconus can occur in one or both eyes and often begins during a person's teens or early 20s.
Keratoconus Symptoms and Signs
Keratoconus can be difficult to detect, because it usually develops slowly. However, in some cases, keratoconus may proceed rapidly.
As the cornea becomes more irregular in shape, it causes progressive nearsightedness and irregular astigmatism to develop, creating additional problems with distorted and blurred vision. Glare and light sensitivity also may occur.
Often, keratoconic patients experience changes in their eyeglass prescription every time they visit their eye care practitioner.
It's not unusual to have a delayed diagnosis of keratoconus, if the practitioner is unfamiliar with the early-stage symptoms of the disease.
What Causes Keratoconus?
New research suggests the weakening of the corneal tissue that leads to keratoconus may be due to an imbalance of enzymes within the cornea. This imbalance makes the cornea more susceptible to oxidative damage from compounds called free radicals, causing it to weaken and bulge forward.
Risk factors for oxidative damage and weakening of the cornea include a genetic predisposition, explaining why keratoconus often affects more than one member of the same family.
Keratoconus is also associated with overexposure to ultraviolet rays from the sun, excessive eye rubbing, a history of poorly fitted contact lenses and chronic eye irritation.
Keratoconus Treatment
In the mildest form of keratoconus, eyeglasses or soft contact lenses may help. But as the disease progresses and the cornea thins and becomes increasingly more irregular in shape, glasses and soft contacts no longer provide adequate vision correction.
Treatments for moderate and advanced keratoconus include:
Gas permeable contact lenses. If eyeglasses or soft contact lenses cannot control keratoconus, then rigid gas permeable (RGP or GP) contact lenses are usually the preferred treatment. Their rigid lens material enables GP lenses to vault over the cornea, replacing its irregular shape with a smooth, uniform refracting surface to improve vision.
Normal eye vs. eye with small amount of keratoconus. The keratoconic cornea bulges slightly, for a more cone-shaped surface. (Artist's re-creation of keratometry images.)
But RGP contact lenses can be less comfortable to wear than soft contacts.
Also, fitting contact lenses on a keratoconic cornea is challenging and time-consuming. You can expect frequent return visits to fine-tune the fit and the prescription, especially if the keratoconus continues to progress.
"Piggybacking" contact lenses. Because fitting a gas permeable contact lens over a cone-shaped cornea can sometimes be uncomfortable for a person with keratoconus, some eye care practitioners advocate "piggybacking" two different types of contact lenses on the same eye.
For keratoconus, this method involves placing a soft contact lens, such as one made of silicone hydrogel, over the eye and then fitting a GP lens over the soft lens. This approach increases wearer comfort because the soft lens acts like a cushioning pad under the rigid GP lens.
Your eye care practitioner will monitor closely the fitting of "piggyback" contact lenses to make sure enough oxygen reaches the surface of your eye, which can be a problem when two lenses are worn on the same eye. However, most modern contacts — both GP and soft — typically have adequate oxygen permeability for a safe "piggyback" fit.
ClearKone hybrid contact lenses. (SynergEyes Inc., Carlsbad, Calif.) These hybrid contact lenses combine a highly oxygen-permeable rigid center with a soft peripheral "skirt." The ClearKone version was designed specifically for keratoconus and vaults above the eye's cone shape for increased comfort.
The manufacturer says hybrid contacts provide the crisp optics of a GP lens and wearing comfort that rivals that of soft contact lenses.
ClearKone hybrid lenses are available in a wide variety of parameters to provide a fit that conforms well to the irregular shape of a keratoconic eye.
Scleral and semi-scleral lenses. Larger diameters found in these gas permeable (GP) lenses enable edges to rest on the eye's white sclera. Scleral lenses cover a larger portion of the sclera, whereas semi-scleral lenses cover a smaller area.
Because the center vaults over the irregularly shaped cornea, this lens doesn't apply pressure to the eye's cone-shaped surface and feels more comfortable. These types of lenses also are more stable than conventional contact lenses, which move with each blink because they cover the cornea only partially.
One example of a scleral lens is the Boston Scleral Lens Prosthetic Device (BSLPD). This cone-shaped device resembles a large contact lens and works partly by maintaining a "pool" of fluid on the eye's surface through which light rays pass and are bent to achieve proper focus.
The BSLPD also fills in a highly irregular eye surface with fluid to help achieve proper focus.
To qualify for the BSLPD, you must have a severe, unusual or otherwise untreatable condition.
In cases of financial need, the non-profit Boston Foundation for Sight providing the lens will help subsidize or pay outright the $7,600 needed for lenses and fittings for both eyes. The price of a lens and fitting for one eye is $5,000.
The BSLPD also has demonstrated effectiveness as a treatment for severe dry eye.
Intacs. (Addition Technology, Des Plaines, Ill.) Intacs, or corneal inserts, received FDA approval for treating keratoconus in August 2004. These tiny plastic inserts are placed just under the eye's surface in the periphery of the cornea and help re-shape the cornea for clearer vision.
Intacs may be needed when keratoconus patients no longer can obtain functional vision with contact lenses or eyeglasses.
Several studies show that Intacs can improve the best spectacle-corrected visual acuity (BSCVA) of a keratoconic eye by an average of two lines on a standard eye chart. The implants also have the advantage of being removable and exchangeable. The surgical procedure takes only about 10 minutes.
Intacs might delay but can't prevent a corneal transplant if keratoconus continues to progress.
Corneal cross-linking. This non-invasive procedure strengthens corneal tissue to halt bulging of the eye's surface in keratoconus. In the United States, FDA clinical trials for corneal collagen cross-linking (CXL) began in early 2008.
Early results showing benefits of this method have been promising. In 2008, University of Siena researchers in Italy reported positive outcomes in all 44 eyes that were followed for three years after treatment with CXL.*
Other researchers have concluded that this simple treatment might reduce significantly the need for corneal transplants among keratoconus patients. Corneal cross-linking also is being investigated as a way to treat or prevent keratoconus-like complications following LASIK or other vision correction surgery.
Research involving a combination of corneal cross-linking with Intacs implants (see above) also has demonstrated early promising results for treating keratoconus.
Corneal transplant. Some people with keratoconus can't tolerate a rigid contact lens, or they reach the point where contact lenses or other therapies no longer provide acceptable vision.
The last remedy to be considered may be a cornea transplant, also called a penetrating keratoplasty (PK or PKP). Even after a transplant, you most likely will need glasses or contact lenses for clear vision.
6-macular degeneration
Age-related macular degeneration, often called AMD or ARMD, is the leading cause of vision loss and blindness among Americans who are age 65 and older. Because people in this group represent an increasingly larger percentage of the general population, vision loss from macular degeneration is a growing problem.
AMD is degeneration of the macula, which is the part of the retina responsible for the sharp, central vision needed to read or drive. Because the macula primarily is affected in AMD, central vision loss may occur.
About 1.75 million U.S. residents currently have advanced age-related macular degeneration with associated vision loss, with that number expected to grow to almost 3 million by 2020.*
Wet and Dry Forms of Macular Degeneration
Macular degeneration is diagnosed as either dry (non-neovascular) or wet (neovascular). Neovascular refers to growth of new blood vessels in an area, such as the macula, where they are not supposed to be.
The dry form is more common than the wet form, with about 85 to 90 percent of AMD patients diagnosed with dry AMD. The wet form of the disease usually leads to more serious vision loss.
Dry Macular Degeneration (non-neovascular). Dry AMD is an early stage of the disease and may result from the aging and thinning of macular tissues, depositing of pigment in the macula or a combination of the two processes.
Dry macular degeneration is diagnosed when yellowish spots known as drusen begin to accumulate in and around the macula. It is believed these spots are deposits or debris from deteriorating tissue. Gradual central vision loss may occur with dry macular degeneration but usually is not nearly as severe as wet AMD symptoms. However, dry AMD through a period of years slowly can progress to late-stage geographic atrophy (GA) — gradual degradation of retinal cells that also can cause severe vision loss.
No FDA-approved treatments are available for dry macular degeneration, although a few now are in clinical trials.
A major National Eye Institute study (AREDS) has produced strong evidence that certain nutrients such as beta carotene (vitamin A) and vitamins C and E may help prevent or slow progression of dry macular degeneration. These findings have led to development of a number of different AREDS nutritional formulas for macular degeneration prevention.
The AREDS study shows that taking high dose formulas of certain nutritional supplements found in eye vitamins may reduce risk of early stage AMD progression by 25 percent.
Eye doctors also recommend that dry AMD patients wear sunglasses with UV protection against potentially harmful effects of the sun.
Macular degeneration mainly affects central vision, causing "blind spots" directly ahead.
Wet Macular Degeneration (neovascular). In about 10 percent of cases, dry AMD progresses to the more advanced and damaging form of the eye disease. With wet macular degeneration, new blood vessels grow beneath the retina and leak blood and fluid. This leakage causes permanent damage to light-sensitive retinal cells, which die off and create blind spots in central vision.
Choroidal neovascularization (CNV), the underlying process causing wet AMD and abnormal blood vessel growth, is the body's misguided way of attempting to create a new network of blood vessels to supply more nutrients and oxygen to the eye's retina. Instead, the process creates scarring, leading to sometimes severe central vision loss.
Wet macular degeneration falls into two categories:
• Occult. New blood vessel growth beneath the retina is not as pronounced, and leakage is less evident in the occult CNV form of wet macular degeneration, which typically produces less severe vision loss.
• Classic. When blood vessel growth and scarring have very clear, delineated outlines observed beneath the retina, this type of wet AMD is known as classic CNV, usually producing more severe vision loss.
Age-Related Macular Degeneration Symptoms and Signs
Age-related macular degeneration usually produces a slow, painless loss of vision. In rare cases, however, vision loss can be sudden. Early signs of vision loss from AMD include shadowy areas in your central vision or unusually fuzzy or distorted vision.
7-Macular dystrophy
Macular dystrophy is a relatively rare eye condition that recently made headlines when Fox News commentator Glenn Beck announced he was going blind because of the disease.
Linked to inherited genetic mutations, macular dystrophy causes deterioration of the inner back lining of the eye where the retina and light-sensitive cells (photoreceptors) are found.
As the name implies, the macula of the retina is affected in macular dystrophy. The macula is the central area of the retina where fine focusing for central vision occurs. When the macula is damaged or scarred due to macular dystrophy, your central vision is affected — and this can lead to blindness in some cases.
What Causes Macular Dystrophy?
Macular dystrophy differs from a far more common eye disease known as macular degeneration, often caused by age-related deterioration of the retina and macula.
While aging or risk factors such as smoking cause common forms of macular degeneration, macular dystrophy is linked to genetic mutations that — for no apparent reason — trigger degradation of retinal cells. Some forms of macular dystrophy appear in childhood, and other forms appear in adulthood.
However, it sometimes is difficult to distinguish common macular degeneration from inherited macular dystrophy because of the similarity of symptoms, including decreased visual acuity and loss of central vision.
One of the most common forms of macular dystrophy is Stargardt's disease, which accounts for about 7 percent of all macular dystrophy cases and commonly occurs in childhood.*
News commentator Glenn Beck reportedly has a type of the eye disease known as vitelliform macular dystrophy (see types of macular dystrophy below).
How Macular Dystrophy Is Diagnosed
Macular dystrophy might be suspected with symptoms such as decreased visual acuity that has no obvious cause, such as refractive errors or cataracts.
A commonly performed eye test known as a fluorescein angiogram also can detect retinal damage from macular dystrophy. However, fluorescein angiograms are not part of routine eye examinations and are used only when suspected retinal conditions are not easily visible to the examining eye doctor.
Your eye doctor may order a test using optical coherence tomography (OCT) to analyze eye tissue for possible presence of a yellow-brown pigment (lipofuscin) found in the retinal pigment epithelium (RPE). Lipofuscin is waste material sloughed off from deteriorating eye tissue.
Another option for diagnosis is an electroretinographic (ERG) test that involves placing an electrode on your eye's outer, clear surface (cornea) to measure how well photoreceptors in your retina respond to light.
Types of Macular Dystrophy
Many forms of macular dystrophy have been identified, including:
Macular Dystrophy and Vision Loss
With any type of advanced macular disease, such as macular dystrophy, images we look at directly are the ones we cannot see well.
For example, imagine that you are looking at a friend standing 10 feet in front of you. When you stare at his or her face, the image you see is being focused through your eye onto your macula — a circular area in the retina in the inner back of your eye that measures only about 2 to 3 mm in diameter.
With early-stage macular disease, your friend's face as you look directly at the eyes may appear to have missing areas. In late-stage macular disease, your friend's face may be replaced completely by a black or gray spot.
As you stare at the face, details are not visible to you. However, if you keep your gaze on your friend's face, your peripheral vision will provide the image of arms, legs and the rest of the body.
Likewise, when you stare directly at your friend's chest, you are using your central vision. So you'll see the same gray or black spot over the chest, but now your peripheral vision will enable you to see the face.
Unfortunately, viewing an object with your peripheral vision still does not allow you to see all the important details of that image. — C.S.
• Stargardt's, the most common type of macular dystrophy, which usually occurs in childhood. A different form of Stargardt's, called fundus flavimaculatus, typically is found in adults. Stargardt's is characterized by formation of pigmented waste cells in the retina.
• Vitelliform macular dystrophy (VTM), which generally is discovered first with the presence of a large, yellow oval lesion (vitelliform) in an egg yolk shape that shows up in the center of the macula. Many genetic mutations of this form of macular dystrophy have been identified, including Best's disease, which affects children and young people. A different version of the disease also can appear in adults, but these lesions vary in size and have shapes such as rings or spots.
• North Carolina macular dystrophy, which is an extremely rare form of the eye disease identified by a very specific genetic marker. While named for North Carolina family members who have this inherited form of macular dystrophy, the disease has been found in other locations worldwide.
Other types of macular dystrophy can cause specific degeneration of light-sensitive cells known as cones. The cones are responsible for color vision and are most concentrated in the macular area of the retina.
While not technically macular dystrophy, retinitis pigmentosa is an inherited photoreceptor dystrophy that destroys light-sensitive cells in the eye.
Treatments for Macular Dystrophy
If you have macular dystrophy, you will need to visit a retinal specialist who will help you determine the exact nature of the disease. For example, some types are progressive and some aren't.
Genetic analysis and counseling may be needed to help you determine the type of macular dystrophy you have and whether the eye condition is likely to be passed on to your children and descendants. Also, you can make better decisions about family planning if you have an idea of the degree of vision loss associated with your type of macular dystrophy.
At this time, there is no proven treatment for macular dystrophy. However, gene therapy has shown promise for treating this and other types of genetic diseases.
As an example, the FDA in March 2010 granted orphan drug status to Advanced Cell Technology (Worcester, Mass.) to test human embryonic stem cells as a treatment for the Stargardt's form of macular dystrophy, with the idea of regenerating damaged cells to support function of photoreceptors. Human clinical trials are expected to begin in the near future. .
Resources:
*Macular dystrophies. Ophthalmology, 3rd ed. 2008.
Macular dystrophy, vitelliform; VMD. National Center for Biotechnology Information (NCBI), U.S. National Library of Medicine website. January 2010.
8-Ocular hypertension
Ocular hypertension means the pressure in your eye — or your intraocular pressure (IOP) — is higher than normal. Elevated IOP also is associated with glaucoma, which is a more serious condition that causes vision loss and optic nerve damage. By itself, however, ocular hypertension doesn't damage your vision or eyes.
According to the Ocular Hypertension Treatment Study, 4.5 to 9.4 percent of Americans age 40 or older have ocular hypertension, which increases their risk of developing sight-threatening glaucoma.*
How Do You Know You Have Ocular Hypertension?
You can't tell by yourself that you have ocular hypertension, because there are no outward signs such as eye pain or redness. During a comprehensive eye exam, your eye care practitioner will measure your IOP and compare it with normal levels.
An eye pressure reading of 21 mmHg (millimeters of mercury) or higher generally signifies ocular hypertension.
If you picture your eye as a globe inflated by pressure, you can better understand why ocular hypertension should be monitored. Pressure that is too high or that continues to increase exerts a force within your eye's interior that can damage the eye's delicate optic nerve, causing glaucoma.
What Causes High Eye Pressure?
Anyone can develop ocular hypertension, but it's most common in African-Americans, people over 40, those with family history of ocular hypertension or glaucoma and those with diabetes or high amounts of nearsightedness.
IOP may become elevated due to excessive aqueous production in the eye or inadequate drainage of this fluid from the eye. Certain medications (such as steroids) and trauma can cause higher IOP as well.
Ocular Hypertension Treatment
Because people with ocular hypertension are at increased risk for developing glaucoma, some eye doctors prescribe eye drops that will lower IOP. Because these medications can have side effects, other eye doctors choose to monitor your IOP and only take action if you show other signs of developing glaucoma.
Because of the increased risk for glaucoma with ocular hypertension, you should have your IOP measured at recommended intervals.
Resources:
*Management of ocular hypertension: a cost-effectiveness approach from the Ocular Hypertension Treatment Study. American Journal of Ophthalmology. June 2006.
Marilyn Haddrill also contributed to this article.
9-Retinitis Pigmentosa
Retinitis pigmentosa (RP) is a rare, inherited disease in which the light-sensitive retina of the eye slowly and progressively degenerates. Eventually, blindness results.
Retinitis Pigmentosa Symptoms and Signs
The first signs of retinitis pigmentosa usually occur in early childhood, when both eyes typically are affected. Night vision can be poor, and the field of vision may begin to narrow.
During later stages of retinitis pigmentosa, only a small area of central vision remains, along with slight peripheral vision.
What Causes RP?
Not much is known about what causes retinitis pigmentosa, except that the disease is inherited. Even if your mother and father don't have retinitis pigmentosa, you can still have the eye disease when at least one parent carries an altered gene associated with the trait.
A shrinking field of vision is one of the early warning signs of retinitis pigmentosa.
In fact, about 1 percent of the population can be considered carriers of recessive genetic tendencies for retinitis pigmentosa that, in certain circumstances, can be passed on to a child who then develops the disease (Ophthalmology 2004).
Rather than being considered a single disease, retinitis pigmentosa instead is viewed as a group of diseases affecting how light-sensitive cells in the back of the eye (retina) function.
Rods — the light-sensing retinal cells that are responsible for vision in dim light — gradually deteriorate until seeing at night becomes more difficult.
Retinitis Pigmentosa Tests and Treatment
Visual field testing likely will be done to determine the extent of peripheral vision loss. Other eye exams may be conducted to determine whether you have lost night or color vision.
No treatments are available currently for retinitis pigmentosa, although some practitioners believe that vitamin A may slightly delay vision loss.
Occupational therapy may be helpful, because it's easier to adjust to declining vision in earlier stages of vision loss.
People with retinitis pigmentosa also might consider using low vision devices that can help magnify and illuminate objects in home and work spaces.
Researchers are looking into ways to treat RP in the future, such as retinal implants and drug treatments.
10-Stargardt's disease
While macular degeneration generally is associated with aging eyes, an inherited form known as Stargardt's disease (STGD) can affect children and young adults.
Stargardt's disease, often mistakenly called Stargate's disease, sometimes is called fundus flavimaculatus. However, some researchers believe a distinction should be made between the two terms, because each describes a different variant of the eye disease.
Stargardt's generally refers to a group of inherited diseases causing light-sensitive cells in the inner back of the eye (retina) to deteriorate, particularly in the area of the macula where fine focusing occurs. Central vision loss also occurs, while peripheral vision usually is retained.
Stargardt's disease is diagnosed by the presence of small, yellowish spots of deteriorating tissue (drusen) sloughed off from the colored or outer covering of the retina (retinal pigment epithelium). Progressive vision loss eventually leads to blindness in most cases.
What Causes Stargardt's Disease?
Stargardt's disease is thought to be passed along to children when both parents carry gene mutations causing the eye disease. Parents can carry recessive genetic traits responsible for Stargardt's, even though they themselves may not have the disease.
Researchers have found that about 5 percent of the human population carry gene mutations causing inherited retinal diseases such as Stargardt's and retinitis pigmentosa.*
How Fast Does Stargardt's Progress?
Vision loss from Stargardt's generally begins to show up within the first 20 years of a young person's life, particularly in early childhood.
But it's difficult to pinpoint exactly when retinal damage will occur or how fast it will progress, because variations can occur even among family members with similar inherited tendencies.
For example, one study reported in the May 2006 issue of American Journal of Ophthalmology noted the case of three siblings, two of whom showed signs of retinal disease in early childhood. But the third sibling was affected beginning at around age 19.
In some cases, a person with Stargardt's (particularly the fundus flavimaculatus version of the disease) may reach middle age before vision problems are noticed.
The reference book Ophthalmology notes that vision loss from Stargardt's as measured on a standard eye chart can range between 20/50 and 20/200. (In the United States, legal blindness is defined as visual acuity of 20/200 or worse while wearing corrective lenses.) Those who have the fundus flavimaculatus form of the disease, however, are likely to experience even more severe vision loss.
Symptoms of Stargardt's disease can include blurry or distorted vision, inability to see in low lighting and difficulty recognizing familiar faces. In late stages of Stargardt's, color vision also may be lost.
Can Stargardt's Disease Be Prevented or Treated?
Some research indicates that exposure to bright light may play a role in triggering the retinal damage that occurs with Stargardt's. While there is no known treatment for Stargardt's disease at this time, people with the condition often are advised to wear eyeglasses or sunglasses with UV protection to reduce the possibility of additional eye damage caused by the sun. If you have Stargardt's, your eye doctor also may suggest that you wear special filters in eyeglasses to block certain wavelengths of light.
Retinal pigment epithelial (RPE) stem cells such as these soon will be used in human clinical trials to regenerate and support function of the eye's light-sensitive cells damaged by Stargardt's disease. (Advanced Cell Technology)
In 2004, UCLA School of Medicine researchers reported promising results when the acne drug Accutane (isotretinoin) was injected into the eyes of mice to help prevent formation of pigmented waste deposits in the eye. These wastes, caused by abnormal processes associated with defective genes in Stargardt's, accumulate in and progressively damage the retina to cause vision loss.
Advanced Cell Technology (Worcester, Mass.) in late 2009 requested FDA approval to test human embryonic stem cells as a treatment for Stargardt's, with the idea of regenerating damaged cells to support function of photoreceptors necessary for sight. In March 2010, the FDA granted orphan drug designation for the company's stem cell treatment, and human clinical trials are expected to begin in the near future.
Vitamin A supplementation should be avoided if you have Stargardt's, because some researchers believe gene mutations lead to abnormal synthesis of the vitamin in the eye, which may help cause associated retinal damage.
Coping With Stargardt's Disease
The American Macular Degeneration Foundation recommends that people with Stargardt's or a history of the eye disease in close family members obtain genetic counseling before starting their own families.
Because vision loss often appears in young children with Stargardt's, low vision counseling from your eye doctor is essential to make sure that classroom learning is not hampered. For example, a child with Stargardt's may need to use large print books and special devices that magnify print. [Read more about low vision devices.]
Resources:
*Ophthalmology (March 2004)
11-Pink Eye (Conjunctivitis)
A pink eye is the most obvious symptom of conjunctivitis, so the term "pink eye" often is used for this common eye problem that can have many different causes.
A pink eye, along with itching, burning, stinging, irritation, pain, grittiness, crusting or light sensitivity, are all symptoms that provide clues about the type of conjunctivitis you could have.
Contagious forms of pink eye are usually linked to bacterial or viral infections. Non-contagious pink eye can occur when eye irritants such as allergens, dust and smoke are in the environment. Coughing and sneezing can spread contagious pink eye by spraying tiny droplets from infected mucus into the air. Shared towels also can be infected, as well as table tops, counter spaces and bathrooms.
However, this figure is dropping dramatically, thanks to a potent combination of drugs used to treat AIDS that help restore function of the immune system. In recent years, these drugs have helped decrease presence of CMV retinitis in late-stage AIDS by more than 80 percent.*
When CMV invades the retina, it begins to compromise the light-sensitive receptors that enable us to see. This does not cause any pain, but you may see floaters or small specks and experience reduced visual acuity (blurry vision) or decreased peripheral vision.
Light flashes and sudden vision loss also can occur. The disease usually starts in one eye but often involves both eyes. If left untreated, CMV retinitis can cause a detached retina and blindness in just two to six months.
AIDS patients sometimes also experience changes to the retina and optic nerve without clear signs of CMV retinitis.
What Causes CMV Retinitis?
CMV retinitis is caused by the cytomegalovirus, a very common virus belonging to the herpes family. About 80 percent of adults harbor antibodies to CMV, which indicates that they have been infected with the virus but their bodies have successfully fought it off.
For people with AIDS, the difference is that their weakened or non-functioning immune system cannot stave off this virus. Other people with a weakened or suppressed immune system, such as those undergoing chemotherapy or a bone marrow transplant, also are at risk. CMV retinitis occurs much less frequently in this group of patients than in the AIDS population.
Stopping vision loss caused by CMV retinitis involves understanding mechanisms of cell death that accompany an infection, Medical College of Georgia School of Medicine virologist and immunologist Sally Atherton, PhD, said in early 2009.
Under a $1.3 million National Eye Institute grant, Dr. Atherton and other researchers are studying how CMV retinitis progresses.
"Normally the retina is neatly stratified. What happens with CMV retinitis is, you get an infection in the most external part of the retina," Dr. Atherton said.
She explained that the virus likely is present but latent on the outer layer of the retina before CMV retinitis develops. Once activated, however, the virus starts to trigger cell death that spreads into deeper layers.
"Unchecked, it can ruin your vision — especially if it affects the macula, or central part of the retina responsible for highest visual acuity," Dr. Atherton said.
The AIDS Toll
According to Centers for Disease Control and Prevention (CDC) statistics released in December 2008, 1.1 million people in the United States are living with HIV/AIDS. These numbers have stabilized in recent years, due largely to public education and prevention efforts.
But with more effective medical intervention, more people infected with HIV are living longer. This means that those with HIV must be vigilant about observing safe sex practices to avoid spreading the disease to others.
In 2004, the CDC estimated that African-Americans accounted for half of the cases diagnosed, even though this group was only 12 percent of the U.S. population.
Non-whites also significantly were more at risk of developing vision loss from CMV retinitis related to AIDS. This finding indicates lack of early treatment and ongoing inequities in the U.S. health system, according to a four-year, Los Angeles County-based study reported in the January 2008 issue of American Journal of Ophthalmology.
Worldwide, the numbers of people living with HIV are declining. In November 2006, the World Health Organization (WHO) estimated that 39.5 million people were living with HIV. In a December 2008 report, WHO said the worldwide number of people with HIV had fallen to 33 million, with 7,500 new infections reported daily.
Most worldwide HIV cases are found in sub-Saharan Africa, where access to treatment is extremely limited. — L.S. & M.H.
CMV Retinitis Treatment
If you have active AIDS and are experiencing visual symptoms, you should see a retina specialist immediately. A person newly diagnosed with CMV retinitis can expect to visit the specialist every two to four weeks.
Once the disease is controlled, those visits may be with your regular eye doctor every three to six months, according to Robert Kalayjian, MD, an infectious disease specialist at Case Western Reserve University School of Medicine in Cleveland.
Drugs for CMV Retinitis. The anti-viral drugs commonly used to treat CMV retinitis are ganciclovir (Cytovene), foscarnet (Foscavir) and cidofovir (Vistide). They can slow down the progression of CMV, but they can't cure it.
Like many drugs, these treatments can cause unpleasant or serious side effects. Until recently, all three were given intravenously, and ganciclovir and foscarnet required an indwelling catheter placed in the chest for daily infusions.
Now, ganciclovir is available in pill form (used following two weeks of intravenous infusion). It also is administered in an intravitreal implant called Vitrasert (Bausch & Lomb).
The implant is inserted inside the eye in the vitreous gel cavity. During a five-to-eight-month period, Vitrasert slowly releases a precise amount of ganciclovir. The medication penetrates directly into the vitreous and the retina, to the source of the CMV retinitis.
Unlike intravenous or oral ganciclovir, Vitrasert typically does not cause systemic side effects such as nausea. Vitrasert is implanted as an outpatient procedure, not requiring hospitalization. The implantation usually takes less than an hour and requires only local anesthesia.
Drugs for HIV. The biggest treatment breakthrough is highly active antiretroviral therapy (HAART), a combination of drugs that suppress the human immunodeficiency virus (HIV), also known as the AIDS virus. HAART allows the immune system of an AIDS patient to recover and fight off infections such as CMV retinitis.
Your doctor may suggest you continue taking anti-CMV drugs for the first three or more months of HAART
A few patients on HAART develop a serious, sight-threatening inflammation inside the eye called immune recovery uveitis. Causes of the inflammation are unclear and require further study.
Also, depending on individual variables, patients with CMV retinitis and who are undergoing various drug treatments can be at higher risk for vision problems such as retinal detachment and cataracts.
Judith Lee also contributed to this article.
2-Diabetic Retinopathy
In later stages, the disease may lead to new blood vessel growth over the retina. The new blood vessels can cause scar tissue to develop, which can pull the retina away from the back of the eye. This is known as retinal detachment, and it can lead to blindness if untreated.
In addition, abnormal blood vessels can grow on the iris, which can lead to glaucoma.
People with diabetes are 25 times more likely to lose vision than those who are not diabetic, according to the American Academy of Ophthalmology.
Diabetic Retinopathy Symptoms and Signs
Everyone who has diabetes is at risk for developing diabetic retinopathy, but not all diabetics do develop it. In its early stages, you may not notice any change in your vision, but it can lead to the later, sight-threatening form of the disease.
Floaters can be a sign of diabetic retinopathy. Sometimes difficulty reading or doing close work can indicate that fluid is collecting in the macula, the most light-sensitive part of the retina. This fluid build-up is called macular edema.
Another sign is double vision, which occurs when the nerves controlling the eye muscles are affected. If you experience any of these signs, see your eye doctor immediately. Otherwise, diabetics should see their eye doctor at least once a year for a dilated eye exam.
Your eye doctor may diagnose retinopathy using a special test called fluorescein angiography. In this test, dye is injected into the body and then gradually appears within the retina due to blood flow. Your eye care practitioner will photograph the retina with the illuminated dye. Evaluating these pictures tells your doctor how far the disease has progressed.
What Causes Diabetic Retinopathy?
Changes in blood-sugar levels increase your risk of diabetic retinopathy, as does long-term diabetes. Generally, diabetics don't develop diabetic retinopathy until they have had diabetes for at least 10 years, but it is not wise to wait that long to have an eye exam. As soon as you've been diagnosed with diabetes, you need to have a dilated eye exam at least once a year.
High blood sugar can damage blood vessels in the retina, and when they are damaged, they can leak fluid or bleed. This causes the retina to swell and form deposits. This is an early form of diabetic retinopathy called nonproliferative or background retinopathy.
In a later stage, called proliferative retinopathy, new blood vessels grow on the surface of the retina. These new blood vessels can lead to serious vision problems because they can break and bleed into the vitreous, the clear, jelly-like substance that fills the center of the eye. Proliferative retinopathy is a much more serious form of the disease and can lead to blindness.
Fortunately, you can significantly reduce your risk of developing diabetic retinopathy by using common sense and taking good care of yourself.
• Keep your blood sugar under good control.
• Monitor your blood pressure and keep it under good control, or seek appropriate care.
• Maintain a healthy diet.
• Exercise regularly.
• Follow your doctor's instructions to the letter.
Diabetic Retinopathy Treatment
According to the American Academy of Ophthalmology, 95 percent of those with significant diabetic retinopathy can avoid substantial vision loss if they are treated in time. The possibility of early detection is why it is so important for diabetics to have a dilated eye exam at least once a year.
Diabetic retinopathy can be treated with laser photocoagulation to seal off leaking blood vessels and destroy new growth. Laser photocoagulation doesn't cause pain, because the retina does not contain nerve endings.
In some patients, blood leaks into the vitreous humor and clouds vision. The eye doctor may choose to simply wait to see if the clouding will dissipate on its own, a period called "watchful waiting." A procedure called a vitrectomy removes blood that has leaked into the vitreous humor. The body gradually replaces lost vitreous humor, and vision usually improves.
If diabetic retinopathy has caused your body to form a cataract, it can be corrected surgically. Patients who have developed glaucoma should see a glaucoma specialist.
Small studies using investigational treatments for diabetic retinopathy have demonstrated significant vision improvement for individuals who are in early stages of the disease. Two treatments that are closely related, Lucentis and Avastin, may be able to stop or reverse vision loss, similar to very promising results that have been reported when the two drugs have been used as treatments for macular degeneration.
Diabetic Retinopathy News
Intensive blood sugar control and combination lipid therapy can slow diabetic retonpathy progression. >>
Lucentis Injections Plus Laser Therapy Improve Vision
In a study of diabetes-associated macular swelling, eye injections of Lucentis, often combined with laser therapy, showed better results than lasers alone. >>
Eye Exam Assistance Program
If you think you can't afford an eye exam but are diabetic, a U.S. citizen, 65 or older and without eye care insurance through an HMO or the VAF, please call 1-800-272-EYES (3937). You may be eligible for a referral for eye exams and up to one year of treatment at no out-of-pocket cost.
Medicare and/or other insurance reimbursement is accepted by the volunteer ophthalmologists as payment in full.
Called the Diabetes EyeCare Program, it is offered by EyeCare America, the public service foundation of the American Academy of Ophthalmology.
3-Eye Herpes
The National Eye Institute (NEI) says an estimated 400,000 Americans have experienced some form of ocular herpes, with close to 50,000 new and recurring cases occurring each year.
Forms of Eye Herpes
Ranging from a simple infection to a condition that can possibly cause blindness, there are several forms of eye herpes:
• Herpes keratitis is the most common form of eye herpes and is a viral corneal infection. Ocular herpes in this form generally affects only the top layer, or the epithelium, of the cornea, and usually heals without scarring.
• Stromal keratitis occurs when the infection goes deeper into the layers of the cornea. This can lead to scarring, loss of vision and, occasionally, blindness. Stromal keratitis is thought to be caused by a late immune response to the original infection. Although the condition is rare, the NEI reports that stromal keratitis is the leading cause of corneal scarring that subsequently causes blindness in the United States.
• Iridocyclitis is a serious form of eye herpes where the iris and surrounding tissues inside the eye become inflamed, causing severe sensitivity to light, blurred vision, pain and redness. Iridocyclitis is a type of uveitis that affects the more frontal portions of the inside of the eye.
When this infection occurs in the retina or the inside lining of the back of the eye, it is known as herpes retinitis.
Eye Herpes Symptoms and Signs
Various signs and symptoms are associated with an ocular herpes outbreak. You may experience inflammation of the cornea, which can cause an irritation or sudden and severe ocular pain. Also, the cornea can become cloudy, leading to blurry vision.
Other characteristics of eye herpes include:
• Swelling around the eyes
• Tearing
• Recurrent eye infections
• Irritation
• Foreign body sensation
• Eye redness
• Eye sores
• Watery discharge
• Sensitivity to light
Due to these numerous symptoms, your eye doctor may overlook an initial diagnosis of ocular herpes in its very early stages.
What Causes Eye Herpes?
Eye herpes is transmitted through contact with another person who is having an outbreak, or through self contact and contamination during an active herpes infection (such as a cold sore of the lip).
The herpes simplex virus enters the body through the nose or mouth and travels into the nerves, where it may be inactive. The virus can remain dormant for years and may never wake up. The exact cause of an outbreak is unknown, but stress-related factors such as fever, sunburn, major dental or surgical procedures and trauma are often associated with incidents.
Once the initial outbreak occurs, the NEI says untreated eye herpes has about a 40-50 percent chance of returning. There is no specific time frame for ocular herpes to reappear; it could be several weeks or even several years following the original occurrence. Although symptoms usually present themselves in only one eye, the virus possibly could affect the other eye as well.
Eye Herpes Treatment
Treatment for eye herpes depends on where the infection is located in the eye — in the corneal epithelium, corneal stroma, iris, retina, etc. Some ocular herpes treatments could aggravate the outbreak and therefore should be considered on a case-by-case basis.
If the corneal infection is only superficial, it can normally be alleviated by using antiviral eye drops or ointments, or oral antiviral pills.
Zirgan (Sirion Therapeutics, Tampa, Fla.) was approved by the FDA in late 2009 as a topical antiviral treatment for eye herpes. The treatment (ganciclovir ophthalmic gel, 0.15 percent), which became commercially available in the United States in late April 2010, involves instilling eye drops five times daily until the related corneal ulcer heals.
You should not wear contact lenses while undergoing treatment with Zirgan, which is marketed in Europe as Virgan.
An eye doctor may treat eye herpes by scraping away the infected corneal epithelial cells with a cotton swab or corneal "spatula" instrument. This is called debridement. Following debridement, a patch or soft contact lens might be needed to help the cornea to heal.
Steroid drops can help decrease inflammation and prevent corneal scarring when the infection appears deeper in the corneal layers. Steroid drops are almost always used in conjunction with and simultaneously with antiviral drops.
Steroid drops decrease the effectiveness of the eye's immune system. Therefore, people with a history of ocular herpes should use only a steroid drop specifically prescribed by their eye doctor.
Steroid drops have been known to cause a recurrent eye herpes infection in susceptible patients. Also, an antibiotic eye drop along with a therapeutic contact lens may be used to prevent a secondary bacterial infection while the herpes eye infection is being treated.
Surgery is required if scarring occurs in the cornea and the treatments including the steroids do not help clear the center of the cornea. In cases where corneal scarring is permanent, a corneal transplant may restore vision.
Although eye herpes has no cure, treatment can help control outbreaks. Studies are underway to determine better methods for managing the disease.
4-Glaucoma
With untreated or uncontrolled glaucoma, you might eventually notice decreased ability to see at the edges of your vision (peripheral vision). Progressive eye damage could then lead to blindness.
In fact, glaucoma creates at least some vision loss in more than half of the approximately 2.5 million Americans estimated to have the eye disease and is the second leading cause of blindness.
Glaucoma Symptoms
Glaucoma often is called the "silent thief of sight," because most types typically cause no pain and produce no symptoms until noticeable vision loss occurs.
For this reason, glaucoma often progresses undetected until the optic nerve already has been irreversibly damaged, with varying degrees of permanent vision loss.
But with acute angle-closure glaucoma, symptoms that occur suddenly can include blurry vision, halos around lights, intense eye pain, nausea and vomiting. If you have these symptoms, make sure you see an eye care practitioner or visit the emergency room immediately so steps can be taken to prevent permanent vision loss.
Diagnosis, Screening and Tests for Glaucoma
An abnormally high IOP reading indicates a problem with the amount of fluid (aqueous humor) in the eye. Either the eye is producing too much fluid, or it's not draining properly.
Normally, IOP should be below 21 mmHg (millimeters of mercury) — a unit of measurement based on how much force is exerted within a certain defined area.
If your IOP is higher than 30 mmHg, your risk of glaucoma damage is 40 times greater than someone with an IOP of 15 mmHG or lower.* This is why glaucoma treatments such as eye drops are designed to keep IOP low.
Other methods of monitoring glaucoma involve the use of sophisticated imaging technology — such as scanning laser polarimetry (SLP), optical coherence tomography (OCT) and confocal scanning laser ophthalmoscopy — to create baseline images and measurements of the eye's optic nerve and internal structures.
Then, at specified intervals, additional images and measurements are taken to make sure no changes have occurred over time that might indicate progressive glaucoma damage.
Visual field testing is a way for your eye doctor to determine if you are experiencing vision loss from glaucoma. Visual field testing involves staring straight ahead into a machine and clicking a button when you notice a blinking light in your peripheral vision. The visual field test may be repeated at regular intervals to make sure you are not developing blind spots from damage to the optic nerve or to determine the extent or progression of vision loss from glaucoma.
Gonioscopy also may be performed to make sure the aqueous humor (or "aqueous") can drain freely from the eye. In gonioscopy, special lenses are used with a biomicroscope to enable your eye doctor to see the structure inside the eye (called the drainage angle) that controls the outflow of aqueous and thereby affects intraocular pressure. Ultrasound biomicroscopy is another technique that may be used to evaluate the drainage angle.
Types of Glaucoma
The two major types of glaucoma are chronic or primary open-angle glaucoma (POAG) and acute angle-closure glaucoma. The "angle" in both cases refers to the drainage angle inside the eye that controls aqueous outflow. Other variations include normal-tension glaucoma, pigmentary glaucoma, secondary glaucoma and congenital glaucoma.
Your eye pressure (intraocular pressure) will be measured with a tonometer. Some tonometers blow a puff of air onto your eye's surface. Others rest gently against the surface of your eye, which will be numbed with eye drops. [Photo: National Eye Institute, National Institutes of Health]
Glaucoma can be very destructive to your vision; in fact, it's the second-leading cause of blindness in the United States.
Primary open-angle glaucoma (POAG). About half of Americans with chronic glaucoma don't know they have it. This common type of glaucoma gradually reduces your peripheral vision without other symptoms. By the time you notice it, permanent damage already has occurred.
If your IOP remains high, the destruction caused by POAG can progress until tunnel vision develops, and you will be able to see only objects that are straight ahead.
Angle-closure glaucoma. Angle-closure or narrow-angle glaucoma produces sudden symptoms such as eye pain, headaches, halos around lights, dilated pupils, vision loss, red eyes, nausea and vomiting.
These signs may last for a few hours, then return again for another round. Each attack takes with it part of your field of vision.
Normal-tension glaucoma. Like POAG, normal-tension glaucoma (also termed normal-pressure glaucoma, low-tension glaucoma or low-pressure glaucoma) is an open-angle type of glaucoma that can cause visual field loss due to optic nerve damage. But in normal-tension glaucoma, the eye's IOP remains in the normal range.
Also, pain is unlikely and permanent damage to the eye's optic nerve may not be noticed until symptoms such as tunnel vision occur.
The cause of normal-tension glaucoma is not known. But many doctors believe it is related to poor blood flow to the optic nerve. Normal-tension glaucoma is more common in those who are Japanese, are female and/or have a history of vascular disease.
Pigmentary glaucoma. This rare form of glaucoma is caused by pigment deposited from the iris that clogs the drainage angle, preventing aqueous humor from leaving the eye. Over time, the inflammatory response to the blocked angle damages the drainage system.
You are unlikely to notice any symptoms with pigmentary glaucoma, though some pain and blurry vision may occur after exercise. Pigmentary glaucoma affects mostly white males in their mid-30s to mid-40s.
Secondary glaucoma. Symptoms of chronic glaucoma following an eye injury could indicate secondary glaucoma, which also may develop with presence of eye infection, inflammation, a tumor or an enlarged cataract.
Congenital glaucoma. This inherited form of glaucoma is present at birth, with 80 percent of cases diagnosed by age one. These children are born with narrow angles or some other defect in the drainage system of the eye.
It's difficult to spot signs of congenital glaucoma, because children are too young to understand what is happening to them. If you notice a cloudy, white, hazy, enlarged or protruding eye in your child, consult your eye doctor. Congenital glaucoma typically occurs more in boys than in girls.
Latest News About Glaucoma
Vitamin E Contacts May Boost Glaucoma Meds
Special contact lenses that contain glaucoma medications are in testing now. >>
Glaucoma-Monitoring Contact Lens
A new contact lens available in Europe called the Triggerfish lets doctors monitor eye pressure in glaucoma patients. >>
Head-Up Sleeping Position May Reduce IOP at Night
If you have high eye pressure (IOP), you may want to consider sleeping with an extra pillow under your head. >>
Glaucoma Treatments
Because glaucoma often is painless, people may become careless about strict use of eye drops that can control eye pressure and help prevent permanent eye damage.
In fact, non-compliance with a program of prescribed glaucoma medication is a major reason for blindness caused by glaucoma.
If you find that the eye drops you are using for glaucoma are uncomfortable or inconvenient, never discontinue them without first consulting your eye doctor about a possible alternative therapy.
5-Keratoconus
Keratoconus can occur in one or both eyes and often begins during a person's teens or early 20s.
Keratoconus Symptoms and Signs
Keratoconus can be difficult to detect, because it usually develops slowly. However, in some cases, keratoconus may proceed rapidly.
As the cornea becomes more irregular in shape, it causes progressive nearsightedness and irregular astigmatism to develop, creating additional problems with distorted and blurred vision. Glare and light sensitivity also may occur.
Often, keratoconic patients experience changes in their eyeglass prescription every time they visit their eye care practitioner.
It's not unusual to have a delayed diagnosis of keratoconus, if the practitioner is unfamiliar with the early-stage symptoms of the disease.
What Causes Keratoconus?
New research suggests the weakening of the corneal tissue that leads to keratoconus may be due to an imbalance of enzymes within the cornea. This imbalance makes the cornea more susceptible to oxidative damage from compounds called free radicals, causing it to weaken and bulge forward.
Risk factors for oxidative damage and weakening of the cornea include a genetic predisposition, explaining why keratoconus often affects more than one member of the same family.
Keratoconus is also associated with overexposure to ultraviolet rays from the sun, excessive eye rubbing, a history of poorly fitted contact lenses and chronic eye irritation.
Keratoconus Treatment
In the mildest form of keratoconus, eyeglasses or soft contact lenses may help. But as the disease progresses and the cornea thins and becomes increasingly more irregular in shape, glasses and soft contacts no longer provide adequate vision correction.
Treatments for moderate and advanced keratoconus include:
Gas permeable contact lenses. If eyeglasses or soft contact lenses cannot control keratoconus, then rigid gas permeable (RGP or GP) contact lenses are usually the preferred treatment. Their rigid lens material enables GP lenses to vault over the cornea, replacing its irregular shape with a smooth, uniform refracting surface to improve vision.
Normal eye vs. eye with small amount of keratoconus. The keratoconic cornea bulges slightly, for a more cone-shaped surface. (Artist's re-creation of keratometry images.)
But RGP contact lenses can be less comfortable to wear than soft contacts.
Also, fitting contact lenses on a keratoconic cornea is challenging and time-consuming. You can expect frequent return visits to fine-tune the fit and the prescription, especially if the keratoconus continues to progress.
"Piggybacking" contact lenses. Because fitting a gas permeable contact lens over a cone-shaped cornea can sometimes be uncomfortable for a person with keratoconus, some eye care practitioners advocate "piggybacking" two different types of contact lenses on the same eye.
For keratoconus, this method involves placing a soft contact lens, such as one made of silicone hydrogel, over the eye and then fitting a GP lens over the soft lens. This approach increases wearer comfort because the soft lens acts like a cushioning pad under the rigid GP lens.
Your eye care practitioner will monitor closely the fitting of "piggyback" contact lenses to make sure enough oxygen reaches the surface of your eye, which can be a problem when two lenses are worn on the same eye. However, most modern contacts — both GP and soft — typically have adequate oxygen permeability for a safe "piggyback" fit.
ClearKone hybrid contact lenses. (SynergEyes Inc., Carlsbad, Calif.) These hybrid contact lenses combine a highly oxygen-permeable rigid center with a soft peripheral "skirt." The ClearKone version was designed specifically for keratoconus and vaults above the eye's cone shape for increased comfort.
The manufacturer says hybrid contacts provide the crisp optics of a GP lens and wearing comfort that rivals that of soft contact lenses.
ClearKone hybrid lenses are available in a wide variety of parameters to provide a fit that conforms well to the irregular shape of a keratoconic eye.
Scleral and semi-scleral lenses. Larger diameters found in these gas permeable (GP) lenses enable edges to rest on the eye's white sclera. Scleral lenses cover a larger portion of the sclera, whereas semi-scleral lenses cover a smaller area.
Because the center vaults over the irregularly shaped cornea, this lens doesn't apply pressure to the eye's cone-shaped surface and feels more comfortable. These types of lenses also are more stable than conventional contact lenses, which move with each blink because they cover the cornea only partially.
One example of a scleral lens is the Boston Scleral Lens Prosthetic Device (BSLPD). This cone-shaped device resembles a large contact lens and works partly by maintaining a "pool" of fluid on the eye's surface through which light rays pass and are bent to achieve proper focus.
The BSLPD also fills in a highly irregular eye surface with fluid to help achieve proper focus.
To qualify for the BSLPD, you must have a severe, unusual or otherwise untreatable condition.
In cases of financial need, the non-profit Boston Foundation for Sight providing the lens will help subsidize or pay outright the $7,600 needed for lenses and fittings for both eyes. The price of a lens and fitting for one eye is $5,000.
The BSLPD also has demonstrated effectiveness as a treatment for severe dry eye.
Intacs. (Addition Technology, Des Plaines, Ill.) Intacs, or corneal inserts, received FDA approval for treating keratoconus in August 2004. These tiny plastic inserts are placed just under the eye's surface in the periphery of the cornea and help re-shape the cornea for clearer vision.
Intacs may be needed when keratoconus patients no longer can obtain functional vision with contact lenses or eyeglasses.
Several studies show that Intacs can improve the best spectacle-corrected visual acuity (BSCVA) of a keratoconic eye by an average of two lines on a standard eye chart. The implants also have the advantage of being removable and exchangeable. The surgical procedure takes only about 10 minutes.
Intacs might delay but can't prevent a corneal transplant if keratoconus continues to progress.
Corneal cross-linking. This non-invasive procedure strengthens corneal tissue to halt bulging of the eye's surface in keratoconus. In the United States, FDA clinical trials for corneal collagen cross-linking (CXL) began in early 2008.
Early results showing benefits of this method have been promising. In 2008, University of Siena researchers in Italy reported positive outcomes in all 44 eyes that were followed for three years after treatment with CXL.*
Other researchers have concluded that this simple treatment might reduce significantly the need for corneal transplants among keratoconus patients. Corneal cross-linking also is being investigated as a way to treat or prevent keratoconus-like complications following LASIK or other vision correction surgery.
Corneal transplant. Some people with keratoconus can't tolerate a rigid contact lens, or they reach the point where contact lenses or other therapies no longer provide acceptable vision.
The last remedy to be considered may be a cornea transplant, also called a penetrating keratoplasty (PK or PKP). Even after a transplant, you most likely will need glasses or contact lenses for clear vision.
6-macular degeneration
AMD is degeneration of the macula, which is the part of the retina responsible for the sharp, central vision needed to read or drive. Because the macula primarily is affected in AMD, central vision loss may occur.
About 1.75 million U.S. residents currently have advanced age-related macular degeneration with associated vision loss, with that number expected to grow to almost 3 million by 2020.*
Wet and Dry Forms of Macular Degeneration
Macular degeneration is diagnosed as either dry (non-neovascular) or wet (neovascular). Neovascular refers to growth of new blood vessels in an area, such as the macula, where they are not supposed to be.
The dry form is more common than the wet form, with about 85 to 90 percent of AMD patients diagnosed with dry AMD. The wet form of the disease usually leads to more serious vision loss.
Dry Macular Degeneration (non-neovascular). Dry AMD is an early stage of the disease and may result from the aging and thinning of macular tissues, depositing of pigment in the macula or a combination of the two processes.
Dry macular degeneration is diagnosed when yellowish spots known as drusen begin to accumulate in and around the macula. It is believed these spots are deposits or debris from deteriorating tissue. Gradual central vision loss may occur with dry macular degeneration but usually is not nearly as severe as wet AMD symptoms. However, dry AMD through a period of years slowly can progress to late-stage geographic atrophy (GA) — gradual degradation of retinal cells that also can cause severe vision loss.
No FDA-approved treatments are available for dry macular degeneration, although a few now are in clinical trials.
A major National Eye Institute study (AREDS) has produced strong evidence that certain nutrients such as beta carotene (vitamin A) and vitamins C and E may help prevent or slow progression of dry macular degeneration. These findings have led to development of a number of different AREDS nutritional formulas for macular degeneration prevention.
The AREDS study shows that taking high dose formulas of certain nutritional supplements found in eye vitamins may reduce risk of early stage AMD progression by 25 percent.
Eye doctors also recommend that dry AMD patients wear sunglasses with UV protection against potentially harmful effects of the sun.
Macular degeneration mainly affects central vision, causing "blind spots" directly ahead.
Choroidal neovascularization (CNV), the underlying process causing wet AMD and abnormal blood vessel growth, is the body's misguided way of attempting to create a new network of blood vessels to supply more nutrients and oxygen to the eye's retina. Instead, the process creates scarring, leading to sometimes severe central vision loss.
Wet macular degeneration falls into two categories:
• Occult. New blood vessel growth beneath the retina is not as pronounced, and leakage is less evident in the occult CNV form of wet macular degeneration, which typically produces less severe vision loss.
• Classic. When blood vessel growth and scarring have very clear, delineated outlines observed beneath the retina, this type of wet AMD is known as classic CNV, usually producing more severe vision loss.
Age-Related Macular Degeneration Symptoms and Signs
Age-related macular degeneration usually produces a slow, painless loss of vision. In rare cases, however, vision loss can be sudden. Early signs of vision loss from AMD include shadowy areas in your central vision or unusually fuzzy or distorted vision.
7-Macular dystrophy
Linked to inherited genetic mutations, macular dystrophy causes deterioration of the inner back lining of the eye where the retina and light-sensitive cells (photoreceptors) are found.
As the name implies, the macula of the retina is affected in macular dystrophy. The macula is the central area of the retina where fine focusing for central vision occurs. When the macula is damaged or scarred due to macular dystrophy, your central vision is affected — and this can lead to blindness in some cases.
What Causes Macular Dystrophy?
Macular dystrophy differs from a far more common eye disease known as macular degeneration, often caused by age-related deterioration of the retina and macula.
While aging or risk factors such as smoking cause common forms of macular degeneration, macular dystrophy is linked to genetic mutations that — for no apparent reason — trigger degradation of retinal cells. Some forms of macular dystrophy appear in childhood, and other forms appear in adulthood.
However, it sometimes is difficult to distinguish common macular degeneration from inherited macular dystrophy because of the similarity of symptoms, including decreased visual acuity and loss of central vision.
One of the most common forms of macular dystrophy is Stargardt's disease, which accounts for about 7 percent of all macular dystrophy cases and commonly occurs in childhood.*
News commentator Glenn Beck reportedly has a type of the eye disease known as vitelliform macular dystrophy (see types of macular dystrophy below).
How Macular Dystrophy Is Diagnosed
Macular dystrophy might be suspected with symptoms such as decreased visual acuity that has no obvious cause, such as refractive errors or cataracts.
A commonly performed eye test known as a fluorescein angiogram also can detect retinal damage from macular dystrophy. However, fluorescein angiograms are not part of routine eye examinations and are used only when suspected retinal conditions are not easily visible to the examining eye doctor.
Your eye doctor may order a test using optical coherence tomography (OCT) to analyze eye tissue for possible presence of a yellow-brown pigment (lipofuscin) found in the retinal pigment epithelium (RPE). Lipofuscin is waste material sloughed off from deteriorating eye tissue.
Another option for diagnosis is an electroretinographic (ERG) test that involves placing an electrode on your eye's outer, clear surface (cornea) to measure how well photoreceptors in your retina respond to light.
Types of Macular Dystrophy
Many forms of macular dystrophy have been identified, including:
Macular Dystrophy and Vision Loss
With any type of advanced macular disease, such as macular dystrophy, images we look at directly are the ones we cannot see well.
For example, imagine that you are looking at a friend standing 10 feet in front of you. When you stare at his or her face, the image you see is being focused through your eye onto your macula — a circular area in the retina in the inner back of your eye that measures only about 2 to 3 mm in diameter.
With early-stage macular disease, your friend's face as you look directly at the eyes may appear to have missing areas. In late-stage macular disease, your friend's face may be replaced completely by a black or gray spot.
As you stare at the face, details are not visible to you. However, if you keep your gaze on your friend's face, your peripheral vision will provide the image of arms, legs and the rest of the body.
Likewise, when you stare directly at your friend's chest, you are using your central vision. So you'll see the same gray or black spot over the chest, but now your peripheral vision will enable you to see the face.
Unfortunately, viewing an object with your peripheral vision still does not allow you to see all the important details of that image. — C.S.
• Stargardt's, the most common type of macular dystrophy, which usually occurs in childhood. A different form of Stargardt's, called fundus flavimaculatus, typically is found in adults. Stargardt's is characterized by formation of pigmented waste cells in the retina.
• Vitelliform macular dystrophy (VTM), which generally is discovered first with the presence of a large, yellow oval lesion (vitelliform) in an egg yolk shape that shows up in the center of the macula. Many genetic mutations of this form of macular dystrophy have been identified, including Best's disease, which affects children and young people. A different version of the disease also can appear in adults, but these lesions vary in size and have shapes such as rings or spots.
• North Carolina macular dystrophy, which is an extremely rare form of the eye disease identified by a very specific genetic marker. While named for North Carolina family members who have this inherited form of macular dystrophy, the disease has been found in other locations worldwide.
Other types of macular dystrophy can cause specific degeneration of light-sensitive cells known as cones. The cones are responsible for color vision and are most concentrated in the macular area of the retina.
While not technically macular dystrophy, retinitis pigmentosa is an inherited photoreceptor dystrophy that destroys light-sensitive cells in the eye.
Treatments for Macular Dystrophy
If you have macular dystrophy, you will need to visit a retinal specialist who will help you determine the exact nature of the disease. For example, some types are progressive and some aren't.
Genetic analysis and counseling may be needed to help you determine the type of macular dystrophy you have and whether the eye condition is likely to be passed on to your children and descendants. Also, you can make better decisions about family planning if you have an idea of the degree of vision loss associated with your type of macular dystrophy.
At this time, there is no proven treatment for macular dystrophy. However, gene therapy has shown promise for treating this and other types of genetic diseases.
As an example, the FDA in March 2010 granted orphan drug status to Advanced Cell Technology (Worcester, Mass.) to test human embryonic stem cells as a treatment for the Stargardt's form of macular dystrophy, with the idea of regenerating damaged cells to support function of photoreceptors. Human clinical trials are expected to begin in the near future. .
Resources:
*Macular dystrophies. Ophthalmology, 3rd ed. 2008.
Macular dystrophy, vitelliform; VMD. National Center for Biotechnology Information (NCBI), U.S. National Library of Medicine website. January 2010.
8-Ocular hypertension
According to the Ocular Hypertension Treatment Study, 4.5 to 9.4 percent of Americans age 40 or older have ocular hypertension, which increases their risk of developing sight-threatening glaucoma.*
How Do You Know You Have Ocular Hypertension?
You can't tell by yourself that you have ocular hypertension, because there are no outward signs such as eye pain or redness. During a comprehensive eye exam, your eye care practitioner will measure your IOP and compare it with normal levels.
An eye pressure reading of 21 mmHg (millimeters of mercury) or higher generally signifies ocular hypertension.
If you picture your eye as a globe inflated by pressure, you can better understand why ocular hypertension should be monitored. Pressure that is too high or that continues to increase exerts a force within your eye's interior that can damage the eye's delicate optic nerve, causing glaucoma.
What Causes High Eye Pressure?
IOP may become elevated due to excessive aqueous production in the eye or inadequate drainage of this fluid from the eye. Certain medications (such as steroids) and trauma can cause higher IOP as well.
Ocular Hypertension Treatment
Because people with ocular hypertension are at increased risk for developing glaucoma, some eye doctors prescribe eye drops that will lower IOP. Because these medications can have side effects, other eye doctors choose to monitor your IOP and only take action if you show other signs of developing glaucoma.
Because of the increased risk for glaucoma with ocular hypertension, you should have your IOP measured at recommended intervals.
Resources:
*Management of ocular hypertension: a cost-effectiveness approach from the Ocular Hypertension Treatment Study. American Journal of Ophthalmology. June 2006.
Marilyn Haddrill also contributed to this article.
9-Retinitis Pigmentosa
Retinitis Pigmentosa Symptoms and Signs
The first signs of retinitis pigmentosa usually occur in early childhood, when both eyes typically are affected. Night vision can be poor, and the field of vision may begin to narrow.
During later stages of retinitis pigmentosa, only a small area of central vision remains, along with slight peripheral vision.
What Causes RP?
Not much is known about what causes retinitis pigmentosa, except that the disease is inherited. Even if your mother and father don't have retinitis pigmentosa, you can still have the eye disease when at least one parent carries an altered gene associated with the trait.
A shrinking field of vision is one of the early warning signs of retinitis pigmentosa.
In fact, about 1 percent of the population can be considered carriers of recessive genetic tendencies for retinitis pigmentosa that, in certain circumstances, can be passed on to a child who then develops the disease (Ophthalmology 2004).
Rather than being considered a single disease, retinitis pigmentosa instead is viewed as a group of diseases affecting how light-sensitive cells in the back of the eye (retina) function.
Rods — the light-sensing retinal cells that are responsible for vision in dim light — gradually deteriorate until seeing at night becomes more difficult.
Retinitis Pigmentosa Tests and Treatment
Visual field testing likely will be done to determine the extent of peripheral vision loss. Other eye exams may be conducted to determine whether you have lost night or color vision.
No treatments are available currently for retinitis pigmentosa, although some practitioners believe that vitamin A may slightly delay vision loss.
Occupational therapy may be helpful, because it's easier to adjust to declining vision in earlier stages of vision loss.
People with retinitis pigmentosa also might consider using low vision devices that can help magnify and illuminate objects in home and work spaces.
Researchers are looking into ways to treat RP in the future, such as retinal implants and drug treatments.
10-Stargardt's disease
Stargardt's disease, often mistakenly called Stargate's disease, sometimes is called fundus flavimaculatus. However, some researchers believe a distinction should be made between the two terms, because each describes a different variant of the eye disease.
Stargardt's generally refers to a group of inherited diseases causing light-sensitive cells in the inner back of the eye (retina) to deteriorate, particularly in the area of the macula where fine focusing occurs. Central vision loss also occurs, while peripheral vision usually is retained.
Stargardt's disease is diagnosed by the presence of small, yellowish spots of deteriorating tissue (drusen) sloughed off from the colored or outer covering of the retina (retinal pigment epithelium). Progressive vision loss eventually leads to blindness in most cases.
What Causes Stargardt's Disease?
Stargardt's disease is thought to be passed along to children when both parents carry gene mutations causing the eye disease. Parents can carry recessive genetic traits responsible for Stargardt's, even though they themselves may not have the disease.
Researchers have found that about 5 percent of the human population carry gene mutations causing inherited retinal diseases such as Stargardt's and retinitis pigmentosa.*
How Fast Does Stargardt's Progress?
Vision loss from Stargardt's generally begins to show up within the first 20 years of a young person's life, particularly in early childhood.
But it's difficult to pinpoint exactly when retinal damage will occur or how fast it will progress, because variations can occur even among family members with similar inherited tendencies.
For example, one study reported in the May 2006 issue of American Journal of Ophthalmology noted the case of three siblings, two of whom showed signs of retinal disease in early childhood. But the third sibling was affected beginning at around age 19.
In some cases, a person with Stargardt's (particularly the fundus flavimaculatus version of the disease) may reach middle age before vision problems are noticed.
The reference book Ophthalmology notes that vision loss from Stargardt's as measured on a standard eye chart can range between 20/50 and 20/200. (In the United States, legal blindness is defined as visual acuity of 20/200 or worse while wearing corrective lenses.) Those who have the fundus flavimaculatus form of the disease, however, are likely to experience even more severe vision loss.
Symptoms of Stargardt's disease can include blurry or distorted vision, inability to see in low lighting and difficulty recognizing familiar faces. In late stages of Stargardt's, color vision also may be lost.
Can Stargardt's Disease Be Prevented or Treated?
Some research indicates that exposure to bright light may play a role in triggering the retinal damage that occurs with Stargardt's. While there is no known treatment for Stargardt's disease at this time, people with the condition often are advised to wear eyeglasses or sunglasses with UV protection to reduce the possibility of additional eye damage caused by the sun. If you have Stargardt's, your eye doctor also may suggest that you wear special filters in eyeglasses to block certain wavelengths of light.
Retinal pigment epithelial (RPE) stem cells such as these soon will be used in human clinical trials to regenerate and support function of the eye's light-sensitive cells damaged by Stargardt's disease. (Advanced Cell Technology)
In 2004, UCLA School of Medicine researchers reported promising results when the acne drug Accutane (isotretinoin) was injected into the eyes of mice to help prevent formation of pigmented waste deposits in the eye. These wastes, caused by abnormal processes associated with defective genes in Stargardt's, accumulate in and progressively damage the retina to cause vision loss.
Advanced Cell Technology (Worcester, Mass.) in late 2009 requested FDA approval to test human embryonic stem cells as a treatment for Stargardt's, with the idea of regenerating damaged cells to support function of photoreceptors necessary for sight. In March 2010, the FDA granted orphan drug designation for the company's stem cell treatment, and human clinical trials are expected to begin in the near future.
Vitamin A supplementation should be avoided if you have Stargardt's, because some researchers believe gene mutations lead to abnormal synthesis of the vitamin in the eye, which may help cause associated retinal damage.
Coping With Stargardt's Disease
The American Macular Degeneration Foundation recommends that people with Stargardt's or a history of the eye disease in close family members obtain genetic counseling before starting their own families.
Because vision loss often appears in young children with Stargardt's, low vision counseling from your eye doctor is essential to make sure that classroom learning is not hampered. For example, a child with Stargardt's may need to use large print books and special devices that magnify print. [Read more about low vision devices.]
Resources:
*Ophthalmology (March 2004)
11-Pink Eye (Conjunctivitis)
A pink eye, along with itching, burning, stinging, irritation, pain, grittiness, crusting or light sensitivity, are all symptoms that provide clues about the type of conjunctivitis you could have.
Contagious forms of pink eye are usually linked to bacterial or viral infections. Non-contagious pink eye can occur when eye irritants such as allergens, dust and smoke are in the environment. Coughing and sneezing can spread contagious pink eye by spraying tiny droplets from infected mucus into the air. Shared towels also can be infected, as well as table tops, counter spaces and bathrooms.
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