Dec. 29, 2004 - A new drug may help slow the gradual loss of vision associated with the leading cause of blindness among the elderly.
New research shows the drug, Macugen, slowed loss of vision as well as reduced the risk of severe vision loss or blindness among older adults with the wet form of age-related macular degeneration, or AMD. The drug, which was recently approved for use by the FDA, doesn't cure the disease, but the study suggests that it can help preserve vision.
Age-related macular degeneration is the leading cause of irreversible blindness among adults over age 55. The prevalence of the condition is expected to rise dramatically in the coming years as the baby boom generation ages.
The wet form of AMD accounts for about 10% of all cases of the disease, but is responsible for 90% of severe vision loss associated with the disorder.
Wet AMD occurs from the growth of abnormal, leaky blood vessels below the retina -- the light sensitive tissue in the back of the eye. The blood and fluid that escape cause damage to central vision, which is required for activities like reading, driving, and recognizing faces.
Macugen was developed to block development of these leaky blood vessels. It does this by blocking a growth factor called VEGF (vascular endothelial growth factor).
If untreated, vision can become severely impaired to the point of legal blindness. However, patients rarely become totally blind, since wet AMD doesn't affect peripheral vision.
New Treatment May Prevent Blindness
In the study, which appears in the Dec. 30 issue of The New England Journal of Medicine, researchers compared the effects of three different dosages of Macugen vs. a placebo in the treatment of more than 1,200 older adults with wet AMD.
All of the participants were over age 50. They were given injections of the drug in the eye or a placebo every six weeks over a period of 48 weeks.
Researchers say as early as six weeks after the treatment began, there was evidence of a reduced risk of vision loss among those treated with Macugen vs. the placebo. These benefits increased over time until week 54 of the study.
The study showed that treatment with Macugen reduced the risk of moderate to severe vision loss. The treatment also reduced the risk of progression to legal blindness. Researchers say treatment with the drug appeared to stabilize vision and a small percentage of patients experienced an improvement in vision by week 54.
Side effects associated with the drug included retinal detachment, injury to the eye lens, and infection.
In an editorial that accompanies the study, Frederick L. Ferris III, MD, of the National Institutes of Health, says the hope is that this is the first step in the development of multiple effective treatments for age-related macular degeneration and other related eye disorders.
"Although this treatment is not all that we would wish for, and although the mechanism of the treatment benefit remains unclear, the study by Gragoudas and colleagues marks the start of a new era in the treatment of age-related macular degeneration," writes Ferris.