Age related macular degeneration (AMD) is the leading cause of blindness in the United States in those people age 55 and over. Over 10 million people in the U.S. suffer from some form of AMD. Even though many new treatments are now available, AMD remains a very prominent cause of blindness and is becoming much more prevalent as the population ages. The area of the eye affected by AMD, the macula, is the area of the back part of the eye, the retina, which provides central vision and is critical for such activities as reading, driving and seeing another person’s face. The disease can be broken down into two main forms: dry and wet.
Dry AMD is the most common form of the disease making up about 80% of all cases. Dry AMD is generally less severe than wet AMD and typically takes a much longer time course for severe vision loss to occur. Treatment options for people with dry AMD are limited, though, and very often the only treatment that can be offered to individuals with dry AMD are vitamins that contain certain anti-oxidants and minerals. In the early stages of dry AMD, the main recommendations that ophthalmologists give the patient is nutritional therapy with an emphasis on consuming foods with high levels of anti-oxidants. This includes dark leafy green vegetables such as kale and spinach.
As dry AMD progresses, supplemental vitamins and minerals are recommended. A large study has shown that a specific combination of vitamins and minerals helps slow down the progression of dry AMD. The age-related eye disease study (AREDS) reported that a nutritional supplement could reduce the risk of developing advanced dry AMD. The original AREDS formula contained beta-carotene, vitamins C & E, zinc and copper. Since the initial study, changes to the supplement, now called AREDS 2, include removal of beta-carotene as it was found to increase the risk of lung cancer formation in smokers. It was replaced with lutein and zeaxanthin. The dosage of zinc was also decreased.
Wet AMD is less common than dry AMD compromising about 20% of all cases. Wet AMD is characterized by the formation of abnormal blood vessels which can cause bleeding and/or fluid leakage into the macula. Wet AMD can occur in a short period of time and patients will usually notice a sudden loss of central vision over a matter of days or weeks. The diagnosis of wet AMD can be made by an ophthalmologist performing a dilated eye exam in which the macula is directly visualized. However, confirmation of the diagnosis is typically made using an instrument known as optical coherence tomographer or OCT. The OCT will show areas of thickening created by bleeding or fluid leakage in the macula.
The treatment of wet AMD has changed dramatically over the last 10 years. Prior to 2006, the best treatment for wet AMD was by using a laser to attempt to seal off the abnormal blood vessels which were leaking into the macula. While laser treatment did improve the vision in patients with wet AMD, only 15% of patients were able to see 20/40 or better which in most states is the legal vision required for driving. Around 2006, retinal specialists began injecting a cancer drug named Avastin into the eyes of patients with wet AMD. Avastin is a drug that blocks the formation of vascular endothelial growth factor or VEGF. By blocking the formation of VEGF, the abnormal blood vessels formed in wet AMD regressed thus preventing the leakage of blood and fluid into the macula. The use of Avastin and another anti-VEGF drug called Lucentis has revolutionized the treatment of wet AMD. Studies have shown that now more than 50% of patients with wet AMD maintain 20/40 or better vision with the use of these anti-VEGF treatments.
In conclusion, while AMD remains one of the leading causes of blindness in the U.S., there is much more optimism in the field of Ophthalmology with the new treatments available for AMD patients. New research is exploring such novel treatments such as long-term implants in the eye to avoid repeat injections for wet AMD patients. Genetic therapy for patients with a predisposition for dry AMD is on the horizon. It is definitely an exciting time in Ophthalmology as we tackle one of the most devasting diseases in our field.