Prepared by Daniel Berinstein, M.D., Retina Service, Yale Eye Center
Age-related macular degeneration (AMD) is the most common cause of legal blindness in the United States and United Kingdom. Approximately 10% of the population over the age of 60 years have evidence of significant AMD with 1% being legally blind (20/200 or worse bilaterally). Three million patients in the U.S. have some loss of vision due to AMD. The only known associated risk factor for AMD is age. Other factors likely to play a role include family history, cardiovascular disease, smoking and nutrition.
Early or "dry" AMD is characterized by the presence of yellow deposits called drusen, and may cause mild to no visual symptoms. Late or "wet" AMD is caused by the growth of abnormal vessels unter the macula, the central part of the retina. These vessels can leak fluid and blood into the eye tissue causing scar tissue and a large blind spot, accounting for the majority of severe visual loss seen in patients.
Prior to last year, there was only one approved means of treating AMD. This treatment, laser photocoagulation, uses high energy laser light to destroy the abnormal blood vessels. Because laser photocoagulation is non-selectie, the overlying and surrounding retina is also destroyed, causing permanent central vision loss. Recently approved by the FDA, photodynamic therapy selectively destroys the abnormal vessels while preserving the overlying retina. Initial reports show PDT to be a promising, safe treatment. Other therapies being evaluated that may have a role in the treatment of AMD include surgical removal of the abnormal blood vessels, rotation of the retina, and specialized medications that prevent the growth of abnormal blood vessels in the eye.