May 20, 1998
An eye operation that moves the most light-sensitive part of the retina away from an underlying diseased area has saved sight in several people with a common, age-related eye disease.
The operation promises to save the vision of thousands of people threatened by age-related macular degeneration (AMD), the major cause of blindness in people over 55 years.
The technique, called macular translocation, is used in cases of AMD in which abnormal blood vessels grow and bleed underneath the retina, according to Eugene de Juan, M.D., professor of ophthalmology at the Wilmer Eye Institute. The growth of abnormal blood vessels occurs in choroid, the layer of blood vessels under the retina, causing the bleeding, or "wet" form of AMD.
"It's almost unheard of for someone with new blood vessels under the central retina caused by AMD to regain normal vision," says de Juan. "In contrast to the natural course of the disease, the vision in the eye of one of my patients improved after surgery from 20/160 to 20/30." A person with 20/160 vision sees clearly an object at 20 feet that a person with normal vision can see clearly at 160 feet. A vision of 20/20 is considered normal.
De Juan, who perfected the technique after modifying earlier, less successful surgical strategies, reports the results of the surgery in the first three patients in the May issue of the American Journal of Ophthalmology. He has now performed the same procedure on a total of 40, about 20 percent of whom have had their vision restored enough to read and drive.
"This technique gives us an important additional therapy used in conjunction with lasers," de Juan says. "The problem with treating the wet form of AMD with the laser is that you also destroy the functioning macula. That's like cutting off a leg to save your life. You end up alive but disabled."
In the new procedure, de Juan pinches the sclera, the white, outer part of the eye, as if it were a hollow rubber ball. Then he puts sutures into the side wall of the eye to keep it pinched, shortening its length. This buckles the retina, which lines the inner wall of the eye. Then de Juan injects a salty solution into the eye under the retina, causing the retina to "blister" up enough so he can move it slightly without detaching it. The average distance the retina must be moved is only about 0.3 to 0.4 millimeters, says de Juan.
"We don't yet know how severe the damage has to be before this surgery is useless," de Juan says. "But anyone who's already had AMD for several months would probably not benefit from this operation. Macular translocation must be done early in the disease. People interested in this treatment should first talk to their own ophthalmologist to determine if the disease has already progressed too far."
De Juan cautions that even when done early in the disease, the surgery doesn't work for everyone and sometimes can worsen vision. "We still need to improve the technique and our understanding of it," says de Juan. "But it does seem to be very useful for some people."
Other authors of the study include Anat Loewenstein, Neil M. Bressler and Judith Alexander.