Macular degeneration is a painless condition that most often occurs in elderly people. It usually affects both eyes, either simultaneously or one after the other. Age-related macular degeneration (AMD) is the leading cause of poor vision in the USA. It usually develops after age 50 and more commonly after age 70 or 80. If you have a family history of macular degeneration your risk of developing the disease is higher. Other risk factors include smoking and high blood pressure. Macular degeneration alone does not cause total blindness, and the remaining peripheral (or side) vision usually allows people with the disorder to take care of themselves quite well and remain relatively self-sufficient.
How Macular Degeneration Develops
The retina is a thin tissue in the back of the eye that functions like the film in a camera. The central part of the retina is called the macula and is responsible for our ability to read small print and perceive minute details. Macular degeneration reduces this aspect of your vision while the peripheral (or side) vision is unaffected. Macular degeneration may begin with only a slight blurring in one or both eyes. It most often progresses slowly but may change rapidly in the “wet” form. Symptoms vary from distorted vision to loss of central vision. Sometimes only one eye loses vision while the other eye continues to see well for many years. If both eyes are severely affected, however, reading and other detailed visual tasks may become extremely difficult or even impossible.
Detection & Diagnosis
Macular degeneration can only be diagnosed by examination of the retina. An Amsler grid test, in which the patient looks at a test pattern, is helpful in detecting the “wet” form at an early stage. If the “wet” form is suspected, a dye test called a fluorescein angiogram may be performed. In this test, a colored dye is injected into a vein in the patient's arm and special photographs are taken as the dye circulates through the blood vessels of the retina. Any abnormal blood vessels become visible as they leak the dye. If macular degeneration is not detected early, vision loss is irreversible. For this reason, it is very important that patients regularly check the vision in each eye separately by covering one eye at a time and ensuring that both eyes can see clearly. This should be done at least once per week to look for distorted, bent or missing areas of vision. This can be done best using an Amsler grid (located on back of brochure) but should still be done if a grid is unavailable by looking at your normal surroundings.
Types & Treatment
There are two types of the disease, “dry” and “wet.” The dry form affects 90% of people while only 10% will get the wet form of the disease. The dry disease is less severe and causes a very slow loss of central vision that can progress over many years. Unfortunately there is very little treatment for the dry disease. The AREDS II multi-vitamin has been proven to reduce the risk of worsening vision loss, but it applies only to patients with moderate to severe dry disease. Although it offers only modest protection, it is the only treatment currently available. If the dry disease progresses far enough, it can result in legal blindness which means your central vision is gone and you cannot drive or read. If the wet disease occurs in one eye, there is a 25% or higher likelihood that it will develop in the other eye in the future.
A person with either form of macular degeneration has some risk that the wet disease can occur. The wet form of the disease causes permanent loss of central vision over days to weeks. It is called “wet” because abnormal blood vessels grow in the macula and either leak fluid or bleed. It almost always begins in one eye at a time and can be treated effectively with injections in the eye.
Ophthalmologist Dimple Modi, MD, MPH is specially trained to evaluate, diagnose and treat macular degeneration. Call the Eye Center to schedule an appointment today. 762.235.3200.