A Better Treatment for Macular Degeneration?
Age related macular degeneration (ARMD) is the leading cause of legal blindness in whites over the age of sixty-five (interestingly, this condition is very rare in African Americans). Considering this fact, the odds are good that every reader of this article knows someone who has lost their vision as a result of this terrible condition. Although the available treatment options are few, new methods for dealing with ARMD are available, which may help to reduce the severe loss of vision associated with this condition.
ARMD is a degeneration of the central (macular) region of the retina. The central retina is responsible for our best vision. You are using the macular region in each of your eyes to read this text. The peripheral retina is responsible for your side vision. We do not fully understood why the central retina is much more susceptible to degenerative changes that rarely occur in the peripheral retina. However, these changes lead to abnormal blood vessel growth, retinal swelling and hemorrhage. The result is loss of central vision and ultimately, blindness.
An effective treatment for ARMD must eliminate the abnormal vessels that grow beneath the retina. Direct treatment of the abnormal blood vessels with the laser has been the main method of treatment to date. However, the laser creates significant heat that can damage healthy retinal tissue, while destroying the abnormal vessels. Could there be a way to treat the abnormal vessels directly, while avoiding damage to healthy retinal tissue? Presently, photodynamic therapy (PDT) and, more importantly, vascular endothelial growth factor inhibitors (anti-VEGF) are the mainstay of treatment.
PDT is a novel, in-office treatment for destroying these blood vessels using chemicals that are activated by an exposure to a low dose of laser irradiation. Patients receive an intravenous injection of a chemical, verteporfin (trade name - Visudyne, CibaVision, USA) that passes through the blood stream and concentrates within the walls of the abnormal blood vessels. The patient then receives a special, low power laser treatment that activates the chemical within the eye. Once activated, the chemical damages the abnormal blood vessel walls, leading to clot formation and vessel destruction. Although the chemical is distributed throughout the entire body, it is only activated in areas where it is exposed to the laser light. Any excess drug is eventually excreted from the body without side effects. This treatment has become less popular as newer, more effective treatments have been developed.
Anti-VEGF treatment modalities include Avastin, Macugen and Lucentis. These medications inactivate the natural biochemical VEGF, a substance that appears to be responsible for the new growth of blood vessels in macular degeneration. In general, they appear to be safe and effective. These medications have recently been released and are actively being used for the treatment of "wet" macular degeneration. All of these medications are directly injected into the eye, and in most cases, multiple injections are necessary to achieve any long term effect.
Unfortunately, none of these treatment methods is a miracle cure. They cannot restore vision to an eye that has been badly damaged by ARMD. Fortunately, these significant breakthroughs may help preserve the vision of thousands of individuals who may otherwise go blind.
