Nov 12 2007
Two particularly notable research presentations at the American Academy of Ophthalmology's Annual Meeting described new approaches to the treatment of "wet" Age-Related Macular Degeneration (AMD), the most common cause of severe vision loss in the western world in people over age 50.
"Wet" AMD is responsible for the majority of AMD-related vision loss. It is characterized by the abnormal growth of blood vessels under the retina (a sensitive area at the back of the eye). New treatments that act on "wet" AMD's abnormal blood vessel growth, such as Avastin and Lucentis, have allowed some patients to obtain meaningful and sustained improvements in vision. These types of medications are sometimes combined with a laser treatment called photodynamic therapy (PDT) and are useful for some "wet" AMD patients. In the United States pharmacotherapies are the most common treatment approach. In parts of the world where injection therapy and PDT may not be available, surgical treatment may be the best alternative.
Milam A Brantley, Jr., MD, PhD, an assistant professor of ophthalmology and visual sciences at Washington University School of Medicine, spoke on how genetic factors may affect the success of Avastin (bevacizumab) treatment; and Zhizhong Ma, MD, a professor of ophthalmology and deputy director at Peking University Eye Center, Beijing, China, described a surgical technique for "wet" AMD that improved vision in 70% of her study's patients.
Dr. Brantley's study is the first to link genetic factors to patients' response to Avastin treatment for "wet" AMD. Previous studies had found variants in two genes, CFH and LOC387715, to be associated with AMD. Dr. Brantley's study looked at 86 patients to see whether having either of these genetic variants affected their responses to Avastin.
"We found that patients with two copies of the CFH variant faired significantly worse than the others in response to treatment with Avastin," Dr. Brantley said, "but we saw no differences in treatment response with the LOC387715 variant. We hope that our study and future, similar research might lead to the development of more individualized AMD treatments that will be more effective and economical."
Adjusting patients' treatments based on genetic tests is also underway or in development in other areas of medicine, such as breast cancer.
New surgical approaches to "wet" AMD are being explored by ophthalmologists around the world. The technique developed by Dr. Ma's group in Beijing, China, achieved unprecedented success in improving patients' vision while also maintaining transplant tissue integrity and incurring fewer complications during or after surgery. This could make a significant difference in AMD treatment in certain population groups.