Age-related macular degeneration (AMD) is the leading cause of blindness in the United States. More than 1 million Americans have neovascular or “wet” AMD and a slightly lower number have “dry” AMD which often progresses to the more severe “wet” form. Since this is a disease of aging, we can expect many more cases as the population expands in the coming years.
Neovascular AMD appears to be related, at lease in part, to excess production of vascular endothelial growth factor (VEGF-A.) A specially developed monoclonal antibody called ranibizumab is available and approved by the FDA for wet AMD. The monoclonal antibody binds to VEGF-A, blocking function and thereby allowing healing of the retina. As a result of decreased vessel growth and decreased leakage, vision can stabilize and frequently actually improve. (See the clinical therapeutics article by Folk and Stone in the New England Journal of Medicine 2010; 363:1648 - 1655 for more details.)
Ranibizumab is injected directly into the eye and an effective concentration lasts for about 30 days. Although not a trivial procedure, it is straight forward in experienced hands and takes but a few minutes in an outpatient setting under topical and local anesthesia. The procedure is repeated in four weeks and in four weeks again. If vision has stabilized or even improved, then the next visit is scheduled in five weeks, then six weeks, etc. It appears that most treatment failures relate to missed follow-ups so attention to timing is very critical.
There is another anti VEGF-A monoclonal antibody, called bevacizumab, approved by the FDA for use in metastatic colon cancer treatment. It costs about $75 for a 1.25 milligram dose whereas ranibizumab costs about $2000 for a comparable dose (0.5 mg.) Although clearly an “off label” use, many retinal specialists will offer bevacizumab as an alternative to ranibizumab and let the patients ultimately decide. Trials comparing the two drugs are underway with results expected in less than a year.
What is clear now is the intraocular injections of anti-VEGF-A monoclonal antibody has substantial efficacy with limited risk.