Silent Blindness

A change in vision should not be casually dismissed as just part of growing older. Fading eyesight could be a symptom of a life-threatening condition, such as diabetes or high blood pressure. Or it might be the early stages of macular degeneration, a progressive disease of the eye affecting more than 10 million Americans.

Types of AMD
Macular degeneration—often called age-related macular degeneration or AMD—is the leading cause of blindness in people 65 and older. The macula, at the center of the retina, is the part of the eye responsible for the detailed central vision essential for tasks such as reading, driving, and recognizing faces. When the macula begins to break down, vision becomes blurred.

“In many ways, it is a silent epidemic of blindness,” says Dr. Jayakrishna Ambati, professor of ophthalmology at the University of Kentucky College of Medicine. “This is a disease that doesn’t get talked about a lot in the general public or in the media, but it takes a huge toll in the quality of life and independence of millions of older Americans.”

There are two basic forms of AMD, known as the “wet” and “dry” types. Wet-type AMD is the more debilitating and rapidly progressing form of the disease, involving invasive growth of new blood vessels under the retina.

Treatment and research
While there is not yet a cure for macular degeneration, treatments are available to slow the progression of the disease and help preserve vision. Because early detection is key to success, Ambati says regular vision checks are essential.

“Certainly, everyone should get an annual eye exam,” Ambati says. “But macular degeneration can progress very rapidly. So anyone who notices a change in vision should be evaluated by an ophthalmologist immediately.”

Ambati’s research is focused on accelerating the discovery of drugs known as angiogenesis inhibitors, which suppress the growth of new blood vessels. Perhaps the most well-known drug in this class is bevacizumab (Avastin), which is used to slow tumor growth in certain types of cancer.

Thomas Reynolds, 75, a retired professor, was referred to Ambati after he was diagnosed with wet-type AMD in November 2006. He was completely blind in his left eye and the vision in his right eye was deteriorating. Reynolds, an avid reader, grew depressed at the prospect of losing his sight.

“The very thought of having it was shocking,” Reynolds says. “I began looking at things as if I were seeing them for the last time.”

Ambati treated Reynolds first with bevacizumab, then with a related drug called ranibizumab. The second treatment was a success: Reynolds’ vision in his right eye improved from 20/100 to 20/40. He is able to read books, and to drive both during the day and at night.

While Ambati believes it will be decades before a cure is discovered, he anticipates a range of treatment options will be developed in the coming decade that could reverse vision loss or even prevent AMD.

“Continued research is critical,” Ambati says. “While there is a great deal of satisfaction in seeing and treating individual patients, research is the only way you can make discoveries that will ultimately translate into saving or restoring the vision of thousands, even millions, of people.”