Retina and Vitreous

Age Related Macular Degeneration (AMD)

Age related macular degeneration (AMD) is one of the most common causes of poor vision after age 60. AMD is a deterioration or breakdown of the macula. The macula is a small area at the center of the retina in the back of the eye that allows us to see fine details clearly and perform activities such as reading and driving.

The visual symptoms of AMD involve loss of central vision. While peripheral (side) vision is unaffected, one loses the sharp, straight-ahead vision necessary for driving, reading, recognizing faces, and looking at detail.

Although the specific cause is unknown, AMD seems to be part of aging. While age is the most significant risk factor for developing AMD, heredity, blue eyes, high blood pressure, cardiovascular disease, and smoking have also been identified as risk factors. AMD accounts for 90 percent of new legal blindness in the US.

Nine out of 10 people who have AMD have the dry form (called atrophic), which results in thinning of the macula. Dry AMD takes many years to develop. Currently there is no treatment for this form of AMD.

The wet form of AMD (called exudative) is less common (occurring in one out of 10 people with AMD), but is more serious. In the wet form of AMD, abnormal blood vessels may grow in a layer beneath the retina, leaking fluid and blood and creating distortion or a large blind spot in the center of your vision. If the blood vessels are not growing directly beneath the macula, laser surgery is the only proven effective treatment, to date, for wet AMD. The procedure usually does not improve vision but prevents further loss of vision. For those wet AMD patients whose blood vessels are growing directly under the center of the macula, a procedure called photodynamic therapy (PDT) may be used to treat some patients with fewer visual side effects than other treatments.

Promising AMD research is being done on many fronts. In the meantime, high-intensity reading lamps, magnifiers and other low-vision aids help people with AMD make the most of their remaining vision.

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Birdshot Retinochoroidopathy (BR)

Birdshot retinochoroidopathy (BR) is a rare, inflammatory condition of the retina and choroid, the layer of blood vessels under the retina. BR usually occurs in Caucasian women over the age of forty.

The cause of BR is unknown. It usually affects both eyes. Symptoms are poor vision, night blindness, and disturbance of color vision. Pain is rare.

Fluorescein angiography, a test for evaluating the retina and choroid, detects BR's characteristic cream-colored spots, similar in appearance to the splattered pattern of birdshot from a shotgun.

BR is a chronic disease that flares up and then goes into remission. Although some people eventually lose vision, others maintain or recover good vision.

If you have been diagnosed with birdshot retinochoroidopathy, it is important to see your ophthalmologist regularly.

Branch Retinal Artery Occlusion (BRAO)

Most people know high blood pressure and other vascular diseases pose risks to overall health, but many may not know that high blood pressure can affect vision by damaging arteries in the eye.

Branch retinal artery occlusion (BRAO) blocks the small arteries in the retina, the light-sensing nerve layer lining the back of the eye. The most common cause of BRAO is a thrombosis, the formation of a blood clot. Sometimes the blockage is caused by an embolus, a clot carried by the blood from another part of the body.

Central vision is lost suddenly if the blocked retinal artery is one that nourishes the macula, the part of the retina responsible for fine sharp vision. Following BRAO, vision can range from normal (20/20) to barely detecting hand movement.

BRAO poses significant risks to vision. If you have had a branch retinal artery occlusion or have high blood pressure, regular visits to your ophthalmologist are essential.

Branch Retinal Vein Occlusion (BRVO)

Most people know high blood pressure and other vascular diseases pose risks to overall health, but many may not know that high blood pressure can affect vision by damaging veins in the eye. High blood pressure is the most common condition associated with BRVO. About 10 to 12 percent of the people who have BRVO also have glaucoma (high pressure in the eye).

Branch retinal vein occlusion blocks small veins in the retina, the layer of light-sensing cells at the back of the eye. If the blocked retinal veins are ones that nourish the macula, the part of the retina responsible for straight-ahead vision, some central vision is lost. During the course of vein occlusion, sixty percent or greater will have swelling of the central macular vision area. In about one third of people, this macular edema will remain for over one year.

BRVO causes a painless decrease in vision, resulting in misty or distorted vision. If the veins cover a large area, new abnormal vessels may grow on the retinal surface, which can bleed into the eye and cause blurred vision.

There is no cure for BRVO. Finding out what caused the blockage is the first step in treatment. Your ophthalmologist may recommend a period of observation, since hemorrhages and excess fluid may subside on their own. Depending on how damaged the veins are, laser surgery may help reduce the swelling and improve vision. Laser surgery may also shrink the abnormal new blood vessels that are at risk of bleeding.

If you have had a branch retinal vein occlusion, regular visits to your ophthalmologist are essential to protect vision.

Central Retinal Artery Occlusion (CRAO)

You probably know high blood pressure and other vascular diseases pose risks to your overall health, but you may not know that they can affect your eyesight by damaging the arteries in your eye.

CRAO usually occurs in people between the ages of 50 and 70. The most common medical problem associated with CRAO is arteriosclerosis, hardening of the arteries. Carotid artery disease is found in almost half the people with CRAO.

The most common cause of CRAO is a thrombosis, an abnormal blood clot formation. Sometimes CRAO is caused by an embolus, a clot that breaks off from another area of the body and is carried to the retina by the bloodstream.

Central retinal artery occlusion (CRAO) blocks the central artery in your retina, the light-sensitive nerve layer at the back of the eye. The first sign of CRAO is a sudden and painless loss of vision that leaves you barely able to count fingers or determine light from dark.

Loss of vision can be permanent without immediate treatment. Irreversible retinal damage occurs after 90 minutes, but even 24 hours after symptoms begin, vision may still be saved. The goal of emergency treatment is to restore retinal blood flow. After emergency treatment, you should have a thorough medical evaluation.

Central Retinal Vein Occlusion (CRVO)

You probably know high blood pressure and other vascular diseases pose risks to overall health, but you may not know that they can affect eyesight by damaging the veins in the eye.

Central retinal vein occlusion (CRVO) blocks the main vein in the retina, the light-sensitive nerve layer at the back of the eye. The blockage causes the walls of the vein to leak blood and excess fluid into the retina. When this fluid collects in the macula—the area of the retina responsible for central vision—vision becomes blurry.

Floaters in your vision are another symptom of CRVO. When retinal blood vessels are not working properly, the retina grows new fragile vessels that leak blood into the vitreous, the fluid that fills the center of the eye. Blood in the vitreous clumps and is seen as tiny dark spots, or floaters, in the field of vision.

In severe cases of CRVO, the blocked vein causes painful pressure in the eye. Retinal vein occlusions commonly occur with glaucoma, diabetes, age-related vascular disease, high blood pressure, and blood disorders.

The first step is finding what is causing the vein blockage. There is no cure for CRVO. Your ophthalmologist may recommend a period of observation, since hemorrhages and excess fluid often subside on their own. Laser surgery may be effective in preventing further bleeding into the vitreous, or for treating glaucoma, but it cannot remove a hemorrhage or cure glaucoma once it is present.

Central Serous Retinopathy (CSR)

Central serous retinopathy is a small, round, shallow swelling that develops on the retina, the light sensitive nerve layer that lines the back of the eye. Although the swelling reduces or distorts vision, the effects are usually temporary. Vision generally recovers on its own within a few months.

In the initial stages of CSR, vision may suddenly become blurred and dim. If the macula‹the area of the retina responsible for acute central vision‹is not affected, there may be no obvious symptoms.

CSR typically affects adults between the ages of 20 to 50. People with CSR often lose their retinal swelling without treatment, and recover their original vision within six months of the onset of symptoms. Some people with frequent episodes may have some permanent vision loss. Recurrences are common and can affect 20 to 50 percent of people with CSR. While the cause of CSR is unknown, it seems to occur at times of major personal or work related stress.

As CSR usually resolves on its own, no treatment may be necessary. Sometimes laser surgery can reduce the swelling sooner but there is no evidence this improves the final visual outcome. If retinal swelling persists for over three to four months or if an examination reveals early retinal degeneration, laser surgery may be helpful.

Coats' Disease

Coats' disease is a chronic, progressive disorder that affects the retina, the light-sensitive nerve layer at the back of the eye. Coats' disease is an abnormal growth spurt of the small blood vessels (capillaries) that nourish the retina. The fragile abnormal vessels break and leak the clear serum part of the blood into the retina, causing the retina to swell.

Coats' disease usually affects children (especially boys) in the first ten years of life, but it can also affect young adults. The condition affects central vision, typically in only one eye. Severity can range from mild vision loss to total retinal detachment and blindness. No cause has yet been identified for Coats' disease.

The leaking blood vessels can be treated with laser surgery or cryotherapy (freezing). If the retina is detached, a vitrectomy to replace the vitreous (the clear gel-like substance inside the eye) with a gas bubble may be necessary to restore vision.

Cotton-Wool Spots

Cotton-wool spots are tiny white areas on the retina, the layer of light-sensing cells lining the back of the eye. Caused by a lack of blood flow to the small retinal blood vessels, they usually disappear without treatment and do not threaten vision. They can, however, be an indication of a serious medical condition.

Diabetes is the most common cause of cotton-wool spots. The presence of more than eight cotton-wool spots has been associated with a higher risk of the more severe form of diabetic retinopathy known as proliferative diabetic retinopathy.

Cotton-wool spots are also a common sign of infection with the Human Immunodeficiency Virus (HIV). They are present in more than half of the people with full-blown AIDS. Their presence can be an important sign of the severity of HIV-related disease.

Cytomegalovirus Retinitis (CMV Retinitis)

CMV retinitis is a serious eye infection of the retina, the light-sensing nerve layer that lines the back of the eye. It is a significant threat to people with weak immune systems, such as people with HIV and AIDS, newborns, the elderly, people taking chemotherapy, and recipients of organ transplants. About 20 to 30 percent of people with AIDS develop CMV retinitis.

Infection with cytomegalovirus, one of the herpes viruses, is extremely common and does not pose a problem for someone with a strong immune system. But when immunity is weak, the CMV can reactivate and spread to the retina through the bloodstream.

First signs of CMV retinitis are loss of peripheral vision or a blind spot which can progress to loss of central vision. Without treatment or improvement in the immune system, CMV retinitis destroys the retina and damages the optic nerve, which results in blindness.

Injection of one or two drugs daily is the current treatment for CMV retinitis. A promising new therapy involves placing a small implant inside the eye that slowly releases the anti-CMV drug ganciclovir.

Warning signs that should be examined by an ophthalmologist immediately are floating spots or spiderwebs, flashing lights, blind spots or blurred vision. Recurrence of CMV retinitis is common so monthly check-ups with an ophthalmologist are important.

Detached and Torn Retina

A retinal detachment is a very serious problem that almost always causes blindness unless treated. The appearance of flashing lights, floating objects, or a gray curtain moving across the field of vision are all indications of a retinal detachment. If any of these occur, see an ophthalmologist right away.

As one gets older, the vitreous, the clear gel-like substance that fills the inside of the eye, tends to shrink slightly and take on a more watery consistency. Sometimes as the vitreous shrinks it exerts enough force on the retina to make it tear.

Retinal tears increase the chance of developing a retinal detachment. Fluid vitreous, passing through the tear, lifts the retina off the back of the eye like wallpaper peeling off a wall. Laser surgery or cryotherapy (freezing) are often used to seal retinal tears and prevent detachment.

If the retina is detached, it must be reattached before sealing the retinal tear. There are three ways to repair retinal detachments. Pneumatic retinopexy involves injecting a special gas bubble into the eye that pushes on the retina to seal the tear. The scleral buckle procedure requires the fluid to be drained from under the retina before a flexible piece of silicone is sewn on the outer eye wall to give support to the tear while it heals. Vitrectomy surgery removes the vitreous gel from the eye, replacing it with a gas bubble, which is slowly replaced by the body's fluids.

Digital Imaging System

The Santamaria Eye Center utilizes the advanced Digital Imaging System which enables the doctor to view the angiogram as it is being perfomed. This is extremely valuable in discussion between patient and doctor to evaluate if further treatment is necessary and helps the patient to understand their condition.

Floaters and Flashes

Small specks or clouds moving in your field of vision as you look at a blank wall or a clear blue sky are known as floaters. Most people have some floaters normally but do not notice them until they become numerous or more prominent.

In most cases, floaters are part of the natural aging process. Floaters look like cobwebs, squiggly lines or floating bugs, and appear to be in front of the eye, but are actually floating inside. As we get older, the vitreous—the clear gel-like substance that fills the inside of the eye—tends to shrink slightly and detach from the retina, forming clumps within the eye. What you see are the shadows these clumps cast on the retina, the light-sensitive nerve layer lining the back of the eye.

The appearance of flashing lights comes from the traction of the vitreous gel on the retina at the time of vitreous separation. Flashes look like twinkles or lightning streaks. You may have experienced the same sensation if you have ever been hit in the eye and seen stars.

Floaters can get in the way of clear vision, often when reading. Try looking up and then down to move the floaters out of the way. While some floaters may remain, many of them will fade over time.

Floaters and flashes are sometimes associated with retinal tears. When the vitreous shrinks it can pull on the retina and cause a tear. A torn retina is a serious problem. It can lead to a retinal detachment and blindness. If new floaters appear suddenly or you see sudden flashes of light, see an ophthalmologist immediately.

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Fluorescein Angiography

Fluorescein angiography, a clinical test to look at blood circulation inside the back of the eye, aids in the diagnosis of retinal conditions associated with diabetes, age-related macular degeneration, and other eye abnormalities. The test can also help follow the course of a disease and monitor its treatment. It may be repeated on multiple occasions with no harm to the eye or body.

Fluorescein, a harmless orange-red dye, is injected into a vein in the arm. The dye travels through the body to the blood vessels in the retina, the light-sensitive nerve layer at the back of the eye. A special camera with a green filter flashes a blue light into the eye and takes multiple photographs of the retina. The technique uses regular photographic film. No X-rays are involved.

If there are abnormal blood vessels, the dye leaks into the retina or stains the blood vessels. Damage to the lining of the retina or atypical new blood vessels may be revealed as well. These abnormalities are determined through a careful interpretation of the photographs by an ophthalmologist.

The dye can discolor skin and urine until it is removed from the body by the kidneys. There is little risk in having fluorescein angiography, though some people may have mild allergic reactions to the dye. Severe allergic reactions have been reported but very rarely. Being allergic to X-ray dyes with iodine does not mean you¹ll be allergic to fluorescein. Occasionally, some of the dye leaks out of the vein at the injection site, causing a slight burning sensation that usually goes away quickly.

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Indocyanine Green Angiography (ICG)

ICG angiography is a clinical test used to detect abnormal blood vessels in the choroid, the layer of blood vessels under the retina. These abnormal blood vessels, typically associated with macular degeneration, may cause bleeding, scarring, and vision loss. If the blood vessels can be restricted by laser surgery, vision loss may be stabilized or improved.

Indocyanine, a harmless green dye, gives off infrared light. When injected into the bloodstream, the dye travels through the veins to the blood vessels in the eye. A video camera connected to a computer picks up the infrared light and makes a picture of the blood's circulation. No film or x-rays are involved.

Following the test, the liver removes the dye. There is little risk in having an ICG angiogram. Some people may have mild allergic reactions and, although rare, a few severe allergic reactions have been reported in people allergic to iodine, X-ray dyes and shellfish.

Lattice Degeneration

Lattice degeneration is thinning and weakening of the retina, the light-sensitive layer of cells lining the back of the eye, that can lead to a retinal tear.

The vitreous, a clear gel-like substance that fills the inside of the eye, is contained in a sac loosely attached to the retina. As one ages, the vitreous takes on a more fluid consistency and the sac sometimes separates from the retina. In lattice degeneration, there are places where the sac is strongly attached to the retina and pulls on it. This pulling weakens the retina and creates lattice lesions that look like white crisscrossing lines on the retina.

If part of the vitreous sac becomes detached from the retina, the friction and pulling where it is still attached can create a tear in the retina. Lattice degeneration can sometimes cause retinal detachments when holes or tears in the lattice formation permit vitreous fluid to get under the retina.

Fortunately, most people with lattice degeneration do not develop a retinal detachment. Preventive treatment of lattice degeneration has not been shown to prevent retinal detachment, but lattice degeneration should be monitored. If you have a history of lattice degeneration, you should be aware of the symptoms of retinal tears and detachment.

Macular Degeneration and Nutritional Supplements

Age-related macular degeneration (AMD) is a disease caused by damage or breakdown of the macula, the small part of the eye's retina that is responsible for our central vision. This condition affects both distance and close vision and can make some activities—like threading a needle or reading—very difficult or impossible. Macular degeneration is the leading cause of severe vision loss in people over 65.

Although the exact causes of AMD are not fully understood, a recent scientific study shows that antioxidant vitamins and zinc may reduce the impact of AMD in some people with the disease.

Among people at high risk for late-stage macular degeneration (those with intermediate AMD in both eyes or advanced AMD in one eye), a dietary supplement of vitamins C, E and beta carotene, along with zinc, lowered the risk of the disease progressing to advanced stages by about 25 to 30 percent. However, the supplements did not appear to benefit people with minimal AMD or those who have no evidence of macular degeneration.

Light may affect the eye by stimulating oxygen, leading to the production of highly reactive and damaging compounds called free radicals. Antioxidant vitamins (vitamins C and E and beta carotene) may work against this activated oxygen and help slow progress of macular degeneration.

Zinc, one of the most common minerals in our body, is very concentrated in the eye, particularly in the retina and macula. Zinc is necessary for the action of over 100 enzymes, including chemical reactions in the retina. Studies show some older people have low levels of zinc in their blood. Because zinc is important for the health of the macula, supplements of zinc in the diet may slow down the process of macular degeneration.

The levels of antioxidants and zinc that were shown to be effective in slowing AMD's progression cannot be consumed through your diet alone. These vitamins and minerals are recommended in specific daily amounts as supplements to a healthy, balanced diet.

It is very important to remember that vitamin supplements are not a cure for AMD, nor will they restore vision you may have already lost from the disease. However, specific amounts of certain supplements do play a key role in helping some people at high risk for advanced AMD to maintain their vision. You should speak with your ophthalmologist to determine if you are at risk for developing advanced AMD, and to learn if supplements are recommended for you.

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Macular Dystrophy

Macular dystrophy is a hereditary condition in which the macula degenerates. The macula is the part of your retina responsible for acute central vision: the vision one uses to read, watch television, and recognize faces.

Symptoms of macular dystrophy can range from minimal vision loss and disturbance of color vision to profound loss of reading and night vision. The most common types of macular dystrophies, which tend to appear early in life, are Best's disease, Staargardt's macular dystrophy, and bull's eye maculopathy.

Considerable research is directed toward finding the hereditary cause of many types of macular dystrophies. With further research it may be possible to develop medical treatments to prevent or slow the progression of macular dystrophy.

Low-vision devices can help affected individuals continue with many of the activities of daily life.

Macular Edema

Macular edema is swelling of the macula, the small area of the retina responsible for central vision. The edema is caused by fluid leaking from retinal blood vessels. Central vision, used for reading and other close detail work, is affected.

Because the macula is surrounded by many tiny blood vessels, anything affecting them, such as a medical condition affecting blood vessels elsewhere in the body or an abnormal condition originating in the eye, can cause macular edema.

Retinal blood vessel obstruction, eye inflammation, and age-related macular degeneration have all been associated with macular edema. The macula may also be affected by swelling following cataract extraction, though typically this resolves itself naturally.

Treatment seeks to remedy the underlying cause of the edema. Eyedrops, injections of cortisone around the eye or laser surgery can be used to treat a macular edema. Recovery depends on the severity of the condition causing the edema.

Macular Hole

The macula is the part of the retina responsible for acute central vision, the vision one uses for reading, watching television, and recognizing faces. A macular hole is a small round opening in the macula. The hole causes a blind spot or blurred area directly in the center of your vision.

Most macular holes occur in the elderly. When the vitreous (the gel-like substance inside the eye) ages and shrinks, it can pull on the thin tissue of the macula, causing a tear that can eventually form a small hole. Sometimes injury or long-term swelling can cause a macular hole. No specific medical problem is known to cause macular holes.

Vitrectomy surgery, the only treatment for a macular hole, removes the vitreous gel and scar tissue pulling on the macula and keeping the hole open. The eye is then filled with a special air bubble to push against the macula and close the hole. The air bubble will gradually dissolve, but the patient must maintain a face down position for one to two weeks to keep the gas bubble in contact with the macula. Success of the surgery often depends on how well the position is maintained.

With treatment, most macular holes shrink and some of the lost central vision slowly returns. The amount of visual improvement typically depends on the length of time the hole was present. Some people with normal vision in the other eye may not want surgery, since vitrectomy surgery cannot completely restore vision.

Nonproliferative Diabetic Retinopathy (NPDR)

If you have diabetes mellitus, your body does not use and store sugar properly. Over time, diabetes can damage blood vessels in the retina, the nerve layer at the back of the eye that senses light and helps to send images to the brain. The damage to retinal vessels is referred to as diabetic retinopathy.

Nonproliferative diabetic retinopathy (NPDR), commonly known as background retinopathy, is an early stage of diabetic retinopathy. In this stage, tiny blood vessels within the retina leak blood or fluid. The leaking fluid causes the retina to swell or to form deposits called exudates.

Many people with diabetes have mild NPDR, which usually does not affect their vision. When vision is affected, it is the result of macular edema and/or macular ischemia.

Macular edema is swelling, or thickening, of the macula, a small area in the center of the retina that allows us to see fine details clearly. The swelling is caused by fluid leaking from retinal blood vessels. It is the most common cause of visual loss in diabetes. Vision loss may be mild to severe, but even in the worst cases, peripheral (side) vision continues to function. Laser treatment can be used to help control vision loss from macular edema.

Macular ischemia occurs when small blood vessels (capillaries) close. Vision blurs because the macula no longer receives sufficient blood supply to work properly. Unfortunately, there are no effective treatments for macular ischemia.

A medical eye examination is the only way to find changes inside your eye. If your ophthalmologist finds diabetic retinopathy, he or she may order color photographs of the retina or a special test called fluorescein angiography to find out if you need treatment. In this test a dye is injected in your arm and photos of your eye are taken to detect where fluid is leaking.

If you have diabetes, early detection of diabetic retinopathy is the best protection against loss of vision. You can significantly lower your risk of vision loss by maintaining strict control of your blood sugar and visiting your ophthalmologist regularly. People with diabetes should schedule examinations at least once a year. Pregnant women with diabetes should schedule an appointment in the first trimester because retinopathy can progress quickly during pregnancy. More frequent medical eye examinations may be necessary after the diagnosis of diabetic retinopathy.

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Ocular Histoplasmosis Syndrome (OHS)

OHS is a major cause of visual impairment in the eastern and central United States where 90 percent of adults have been exposed to histoplasma capsulatum. This common fungus is found in molds from soil enriched with bat, chicken or starling droppings and yeasts from animals.

Although the fungus is not found directly in the eye, people with OHS usually test positive for previous exposure to histoplasma capsulatum.

Histoplasmosis is usually mistaken for a cold. The symptoms are very similar. The body's immune system normally overcomes the infection in a few days. The only evidence of histoplasmosis is histo spots, tiny scars on the retina. Generally histo spots do not affect vision, but for unknown reasons, some people can have ocular complications years or decades later.

Doctors believe that the histoplasmosis spores travel from the lungs to the eye where they settle in the choroid, the layer of tiny blood vessels that provides blood and nutrients to the retina, the light-sensing layer of cells lining the back of the eye.

Ocular histoplasmosis develops when fragile, abnormal blood vessels grow under the retina. The abnormal blood vessels form a lesion known as choroidal neovascularization (CNV). If left untreated, the CNV lesion can turn into scar tissue and replace the normal retinal tissue in the macula.

The only proven treatment for OHS is a form of laser surgery called photocoagulation. The laser's small, powerful beam of light destroys the abnormal blood vessels, as well as a small amount of the retinal tissue. Treatment is not necessary unless the new vessels are in the macula, the part of the retina responsible for acute central vision.

Although only a tiny fraction of people infected with the histoplasmosis virus develop OHS, if you have been exposed to histoplasmosis you should be sensitive to any changes in your eyesight.

Photodynamic Therapy for Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a deterioration or breakdown of the macula. The macula is a small area at the center of the retina in the back of the eye that allows us to see fine details clearly and perform activities such as reading and driving. In the wet form of AMD, abnormal blood vessels may grow in a layer beneath the retina, leaking fluid and blood and creating distortion or a large blind spot in the center of your vision.

Photodynamic therapy (PDT)—an outpatient procedure involving the use of a special light-activated drug—may be used to treat some patients with the wet form of AMD with fewer visual side effects than other treatments. The benefit of PDT is that it inhibits abnormal blood vessel leakage associated with wet macular degeneration, limiting damage to the overlying retina.

In PDT, the inactive form of the drug is usually injected into a vein in the arm, where it travels to and accumulates in abnormal blood vessels under the center of the macula. A special low-intensity laser light targeted at the retina activates the drug only in the affected area, damaging the abnormal blood vessels under the retina and leaving normal blood vessels intact.

Patients who are treated with PDT will become temporarily sensitive to bright light (photosensitive). Care should be taken to avoid exposure of skin or eyes to direct sunlight or bright indoor light for several days.

PDT therapy is not effective for treatment of the dry form of AMD, caused by aging and thinning of the tissues of the macula. While photodynamic therapy may preserve vision for many people, PDT may not stop vision loss in all patients. The abnormal blood vessels may regrow or begin to leak again. Every three months, a repeat examination including a fluorescein angiogram (a dye test) is required. Multiple PDT treatments may be necessary.

Proliferative Diabetic Retinopathy (PDR)

Proliferative diabetic retinopathy is a complication of diabetes caused by changes in the blood vessels of the eye. If you have diabetes, your body does not use and store sugar properly. High blood sugar levels create changes in the veins, arteries and capillaries that carry blood throughout the body. This includes the tiny blood vessels in the retina, the light-sensitive nerve layer that lines the back of the eye.

In PDR, the retinal blood vessels are so damaged they close off. In response, the retina grows new, fragile blood vessels. Unfortunately, these new blood vessels are abnormal and grow on the surface of the retina, so they do not resupply the retina with blood.

Occasionally, these new blood vessels leak and cause a vitreous hemorrhage. Blood in the vitreous, the clear gel-like substance that fills the inside of the eye, blocks light rays from reaching the retina. A small amount of blood will cause dark floaters, while a large hemorrhage might block all vision, leaving only light and dark perception.

The new blood vessels can also cause scar tissue to grow. The scar tissue shrinks, wrinkling and pulling on the retina and distorting vision. If the pulling is severe, the macula may detach from its normal position and cause vision loss.

Laser surgery may be used to shrink the abnormal blood vessels and reduce the risk of bleeding. The body will usually absorb blood from a vitreous hemorrhage, but that can take days, months or even years. If the vitreous hemorrhage does not clear within a reasonable time, or if a retinal detachment is detected, an operation called a vitrectomy can be performed. During a vitrectomy, the eye surgeon removes the hemorrhage and the abnormal blood vessels that caused the bleeding.

People with PDR sometimes have no symptoms until it is too late to treat them. The retina may be badly injured before there is any change in vision. There is considerable evidence to suggest that rigorous control of blood sugar decreases the chance of developing serious proliferative diabetic retinopathy.

Because PDR often has no symptoms, if you have any form of diabetes you should have your eyes examined regularly by an ophthalmologist.

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Retinitis Pigmentosa (RP)

Retinitis pigmentosa (RP) describes a group of related diseases that tend to run in families and cause a slow but progressive loss of vision. RP affects the rods and cones of the retina, the light-sensitive nerve layer at the back of the eye, and results in a decline in vision in both eyes. RP usually affects both eyes equally with severity ranging from no visual problems in some families to blindness at birth in others. RP gets its name from the fact that one of the symptoms is a clumping of the retinal pigment that can be seen during an eye exam.

The earliest symptom of retinitis pigmentosa, usually noticed in childhood, is night blindness or difficulty with night vision. People with normal vision adjust to the dark quickly, but people with night blindness adjust very slowly or not at all. A loss of side vision, or tunnel vision, is also common as RP progresses. Unfortunately, the combination of night blindness and the loss of peripheral vision can be severe and lead to legal blindness in many people.

While there is a pattern of inheritance for RP, 40% of RP patients have no known previous family history. Learning more about RP in your family can help you and your ophthalmologist predict how RP will affect you.

Usher's syndrome, in which a person is both deaf and blind, can be associated with RP. The incidence of Usher's syndrome is difficult to determine but surveys of patients suggest up to 10% of RP patients are deaf. The incidence of Usher's syndrome is three cases per 100,000. It is the most frequent cause of combined deaf-blindness in adults.

Considerable research is being done to find the hereditary cause of RP. As hereditary defects are discovered it may be possible to develop treatments to prevent progression of the disease. While developments are on the horizon, particularly in the area of genetic research, there is currently no cure for retinitis pigmentosa.

Nutritional supplements may have an effect on RP. It has been reported that Vitamin A can slow the progression of RP. Large doses of Vitamin A are harmful to the body and supplements of Vitamin E alone may make RP worse. Vitamin E is not harmful if taken with Vitamin A or in the presence of a normal diet. Your ophthalmologist can advise you about the risks and benefits of Vitamin A and how much you can safely take.

Despite visual impairment, people with RP can maintain active and rewarding lives through the wide variety of rehabilitative services that are available today. Until there is a cure, periodic examinations by your ophthalmologist will keep you informed of legitimate scientific discoveries as they develop.

Retinoblastoma

Retinoblastoma, a malignant tumor that grows in the retina, the layer of light-sensing cells in the back of the eye, can destroy a child's vision and be fatal. Affecting children of all races, boys and girls equally, retinoblastoma occurs in one or both eyes, usually in the first year or two of life.

The most common sign is a change in the color of the pupil, which can appear white in reflected light. This phenomenon is referred to as a cat's eye reflex. Sometimes the affected eye will cross or turn outward. Retinoblastoma can be hereditary and is more likely to develop in children with a family history of the disease.

With early diagnosis, retinoblastoma treatment is remarkably effective. More than 90% of children survive and many eyes are saved with a combination of medications, radiation therapy, and heat, freezing, or laser treatments. In severe cases, the affected eye is removed.

If a child has had retinoblastoma there is an increased chance for a second cancer to develop. Children with retinoblastoma should have regular examinations by an ophthalmologist and a pediatric oncologist.

Retinopathy of Prematurity (ROP)

Retinopathy of Prematurity (ROP) damages premature babies' retinas, the layer of light-sensitive cells lining the back of the eye. ROP usually occurs in both eyes, though one may be more severely affected.

The last 12 weeks of a full-term pregnancy are an especially active time for the growth of the eye. When a baby is born prematurely, blood vessels are not ready to supply blood to the retina. At birth, abnormal new blood vessels form and cause scarring or detachment of the retina. The condition is especially common in very small babies. It is more likely to occur at one or two pounds than at three pounds.

Despite improved medical care, the disease is becoming more common because smaller and sicker infants are surviving. Supplemental oxygen given to premature babies may be part of the cause of ROP, but not the only factor, as once thought.

In severe cases, the retina may be extremely scarred and detached. Many cases get better without treatment and only a small number of children go blind. Freezing (cryotherapy) or laser treatments can prevent progression of the disease.

Children with ROP are more likely to develop nearsightedness and amblyopia (lazy eye). Glasses, patching, and eye muscle surgery can help these associated problems. Follow-up exams of severely affected children should continue periodically.

Vitrectomy

Vitrectomy is the surgical removal of the vitreous gel from the inside of the eye. This is done by inserting small instruments into the pars plana (the area between the iris and the retina), cutting the vitreous gel, and suctioning it out. This procedure is done by a specialized ophthalmic surgeon.

A Vitrectomy can be done to aid in the treatment or repair of: Vitreous Floaters, Retinal Detachment, Macular Pucker/Epiretinal Membrane (formation of "wrinkle" in the macula that distorts vision), severe Proliferative Diabetic Retinopathy, Macular Holes and Vitreous Hemorrhage.

At the end of the surgery, fluid, silicone oil or a gas is injected into the eye to replace the vitreous gel and restore normal pressure in the eye. If gas is injected, the patient may be required to maintain a face-down position until the gas resorbs, to keep the retina in place. On the other hand, if silicon oil is injected, the patient will need another surgery to remove it in the future.

Along with the usual complications of surgery, such as infections, vitrectomy can result in retinal detachment. A more common complication is high intraocular pressure, bleeding in the eye, and cataracts (the most frequent complication of vitrectomy). Many patients will develop a cataract within the first few years after a vitrectomy or if they already have a cataract, it usually gets worse after surgery.