Macular Degeneration
One of the most common causes of legal blindness in the USA in patients over 50 years old is macular degeneration. This is a condition that is often related to aging, and is often abbreviated as AMD. The cause is unknown, but it affects about 9 million Americans over the age of 40.
In AMD, the center of the retina, called the macula, is affected. This is particularly devastating, since the macula is the part of the eye that allows us to see fine detail like reading, recognizing faces, or watching television. The importance of the macula to sight cannot be overestimated — over 90% of all nerves carrying visual signals originate from the macula.
The early stages usually start with spots appearing and accumulating under the retina. These spots are called drusen. Vision is not usually affected at this stage. Around 80-90% of all patients with AMD remain at this stage without progression to the late stage.
Most often, progression to the late stage occurs in one eye first, accompanied by vision loss. Since the other eye can still function well, often the loss of vision can go unnoticed. Often, it is only when AMD affects both eyes that difficulties with vision arise. There are two forms of the late stage, often divided into the “dry” and “wet” forms.
The dry form can arise from drusen that have been present for a long time. The retina (more specifically, the macula.) becomes thin and damaged, and stops functioning. This leads to a dark or blank spot in the central vision. Unfortunately, there is no treatment for the dry form of AMD.
The wet form of AMD is responsible for up to 90% of the severe visual loss that is associated with AMD. The presence of drusen may lead to the formation of abnormal blood vessels under the retina in the macular area. These abnormal blood vessels leak fluid and blood, and lead to scar formation and loss of central vision. There are various laser treatment possibilities for the wet form of AMD, but the treatment is not appropriate for all patients. After laser treatment, a scar is formation that may decrease vision, but the amount of visual loss is usually less with the treatment than without the laser treatment.
Recently, a large study identified certain vitamins and minerals that may delay the progression of AMD in certain patients. However, these dietary supplements should be taken with care since high doses can lead to serious health consequences.
Early detection and treatment still remain the best method to retain vision in an eye affected by AMD — one useful test is the Amsier grid, which can be performed at home in minutes.
