Age-Related Macular Degeneration by Esther M Bowie, MD
Age-related macular degeneration (AMD) is the leading cause of blindness in patients over 50 years old in industrialized countries. Although the exact cause is unknown, there is a strong genetic component. There are two types of macular degeneration, the “dry” (non-exudative, atrophic) type and the “wet” (exudative, neovascular) type although the dry type is the most common form. AMD causes a slowly progressive loss in central vision. As the dry macular degeneration progresses it causes a blurry spot in the central vision. The wet type is caused by abnormal blood vessel growing beneath the retina which can bleed and leak fluid, resulting in straight lines becoming wavy and a sudden loss of central vision. AMD is diagnosed by having a dilated eye examination where the visual acuity is checked. An Amsler grid pattern of horizontal and vertical lines is checked. In AMD these lines may become wavy or section may be missing. The pupil is dilated to look at the macula which may show yellow deposits called drusen, pigment clumping or bleeding. Other tests, such as Fluorescein angiography, in which a yellow dye is injected into a vessel in the arm, may also be performed. The dye passes quickly to the vessels at the back of the eye and pictures are taken. This test will help the ophthalmologist to detect abnormal blood vessels that may be leaking.
Patients with AMD are asked to monitor their vision with the Amsler grid and call their ophthalmologist if distortions or missing areas are noted. The Age-Related Eye Disease Study (AREDS) demonstrated that antioxidants and zinc may delay the progression in some patients with AMD.
Treatment options available for AMD are rapidly advancing. Macugen (Pegaptanib sodium injection) has been recently approved by the FDA for treatment of all types of wet macular degeneration. Macugen acts by blocking vascular endothelial growth factor (VEGF). Patients with wet AMD have elevated levels of VEGF. VEGF causes blood vessels to grow and leak which results in vision loss. Macugen is injected in the eye every 6 weeks. Verteporfin photodynamic therapy (PDT) is another therapy for wet AMD. PDT involves the injection of verteporfin a photosensitizing drug in a blood vessel in the arm. The drug is then activated by light from a laser, this causes thrombosis (closure) of the abnormal blood vessels selectively. Thermal laser, another treatment option is indicated in only a few of patients with wet AMD. The abnormal blood vessels are destroyed with a hot laser. Despite these approved therapies they are not very effective in improving vision. Low vision training is a good option for many patients with advanced AMD.There is ongoing research with other anti-angiogenic such as ranibizumab (LucentisTM) and bevacizumab (AvastinTM) and Anecortaveacetate.
Despite all the advances we still have to find therapy to prevent vision loss. Specialists, such as those at Storm Eye Institute at the Medical University of South Carolina, are working hard to prevent vision loss in patients with age-related macular degeneration. If you have questions or feel you may be at risk for this disease, contact your ophthalmologist for a full evaluation or call Storm Eye Institute at (843) 792-8100. |
