Retinopathy

What Is It?

Retinopathy refers to diseases that affect the retina, the collection of light-sensitive cells lining the back half of each eye. The retina contains nerve cells that translate what you see into electrical impulses. These impulses are transmitted to the brain, where they are interpreted.

The retina contains many blood vessels. Abnormalities in these vessels cause several forms of retinopathy. Retinopathy can cause partial loss of vision or complete blindness. It can develop slowly or occur suddenly. Retinopathy can get better on its own at any time or it can cause permanent damage, depending on what's causing it and how far it has progressed.

Some types of retinopathy (for example, central serous retinopathy) do not have an obvious cause. Most forms of retinopathy, though, are caused by a known medical illness. Types of retinopathy caused by illnesses include:

• Retinopathy of prematurity occurs in some infants who are born prematurely or at a low birth weight. Retinal blood vessels develop at the back of the eye and grow outward to cover the area of the retina. When a child is born too early, this process doesn't have time to finish. An eye doctor (ophthalmologist) should closely monitor infants who are at risk by carefully examining the eyes. A baby is at risk if the baby is born before the mother finishes her 29 ^th week of pregnancy, or if the baby weighs less than 1200 grams at birth. Babies who are born before the mother finishes the 35 ^th week of pregnancy or who have a birth weight less than 1500 grams may also need an eye examination, if they have had other complications from their premature birth. Early stages of this illness involve only subtle changes without obvious symptoms. In more advanced stages, the retina can become detached, causing blindness.

• Diabetic retinopathy develops in people with diabetes. Two kinds of diabetic retinopathy have the potential to diminish vision: nonproliferative and proliferative retinopathy. In nonproliferative retinopathy, existing blood vessels in the retina deteriorate. Deteriorating blood vessels can become blocked or can develop balloon-like deformities called aneurysms. Fluids, fats and proteins leak out of the abnormal blood vessels. Fluid can collect in the area of the retina that is responsible for sharp vision (the macula). Macular swelling (edema) impairs the fine vision necessary for reading and detail work. In proliferative retinopathy, new, structurally unstable blood vessels grow on the surface of the retina. These unstable blood vessels cause frequent small hemorrhages (bleeding), causing local irritation with scar formation. In areas that have scarred, the clear mass of gel between the lens and the retina, called the vitreous, can adhere to the retina. These abnormal attachments between the retina and vitreous eventually distort the shape of the vitreous and cause the vitreous to pull against its tethers. This force can pull apart the layers of the retina, so that the retina can't function. This separation of layers is known as retinal detachment and is one of the most serious consequences of proliferative retinopathy. Sudden bleeding into the vitreous also can obscure vision, often quite suddenly. Diabetic retinopathy takes years to develop, but it is present in close to 80% of people with type 1 or type 2 diabetes who are treated with insulin, and who have had diabetes for 20 years or longer. People who do not manage their diabetes with insulin are less likely to develop retinopathy, with 20% showing eye abnormalities 20 years after they were diagnosed with diabetes. People with diabetic retinopathy usually also have kidney damage caused by diabetes. Diabetic retinopathy is the leading cause of blindness in the United States for people between the ages of 20 and 64.

• Hypertensive retinopathy occurs in people who have high blood pressure (hypertension). It results from the thickening of the small arteries. Despite the potentially serious nature of high blood pressure, people with this disease frequently have no symptoms. Hypertensive retinopathy sometimes is discovered during a routine eye exam. High blood pressure causes blood vessel abnormalities, including blockages of retinal blood vessels and bleeding from them. These changes may not affect vision in early stages. Sudden, severe high blood pressure may cause swelling of the optic nerve (papilledema).

• Central serous retinopathy begins for reasons that are not well understood. In this condition, fluid accumulates in the membrane behind your retina, called the choroid. This fluid seeps in between tissue layers in the retina and causes them to separate, resulting in blurred vision or poor night vision. This condition usually affects males between the ages of 20 and 50, but women can also get this condition. Before developing this diagnosis, a person who develops this retinopathy is more likely than average to have been exposed to certain treatments or to have had certain medical problems, so these treatments and conditions are suspected to be possible triggers. Suspected triggers include steroid medicines, pregnancy, antihistamines, antibiotics, alcohol abuse, nasal allergies or asthma, autoimmune problems, and hypertension that has remained untreated. It is not clear whether emotional stress may also trigger this form of retinopathy, although some experts suspect a link.