Macular Degineration
Parts Of Visual System Affected
Macular degeneration is caused by the deterioration of the central portion of the retina, the inside back layer of the eye that records the images we see and sends them via the optic nerve from the eye to the brain. The retina's central portion, known as the macula, is responsible for focusing central vision in the eye.
Description
Age-related macular degeneration (AMD) is a progressive disease of the retina wherein the light-sensing cells in the central area of vision (the macula) stop working and eventually die. The disease is thought to be caused by a combination of genetic and environmental factors, and it is most common in people who are age sixty and over.
Stargardt's disease
This is the most common type of JMD. Symptoms typically develop in childhood or teen years. However a variant of Stargardt's disease, called fundus flavimaculatus, has the same symptoms, but they do not become manifest until early adulthood. Symptoms include decline in visual acuity, drusen spots on the macula and scarring of the macula. Stargardt's disease has an autosomal recessive pattern of inheritance.
Effects Of The Condition On Visual System
During the early stages of macular degeneration, and if only one eye is affected, there may be no symptoms. Additionally, neither form of macular degeneration (dry or wet) causes pain. However, an ophthalmologist may be able to detect early signs of the disease before symptoms appear. Therefore, it is very important to have regular eye examinations to detect these signs as soon as possible.
Often, the dry form of macular degeneration initially causes slightly blurred central vision, both close up and far. The center of vision may become fuzzy or shadowed, and this area grows larger as the disease progresses. Blind spots may develop, and it is normally more difficult to see color and fine detail.
Commonly, in wet macular degeneration, in addition to the above symptoms, straight lines may appear wavy. Also, in this more severe form, central vision loss can occur rapidly, sometimes within days or weeks.
Treatments
Taking a high-dose formulation of antioxidants and zinc may reduce progression of dry macular degeneration to advanced macular degeneration. The National Eye Institute- sponsored Age-Related Eye Disease Study (AREDS) showed that a daily supplement of 500 milligrams (mg) of vitamin C, 400 international units (IU) of vitamin E, 15 mg of beta carotene (often as vitamin A — up to 25,000 IU), 80 mg of zinc (as zinc oxide) and 2 mg of copper (as cupric oxide) reduced the risk of progressing to moderate or severe vision loss by up to 25 percent.
It is likely that researchers will try to invent ways to minimize the adverse impact of genes which cause Juvenile Macular Degeneration. For example, drugs may be developed which either inhibit synthesis of faulty TIMP-3 protein, or which interfere with its harmful effect. Such drugs might prevent Sorsby's disease symptoms. Unfortunately, because Sorsby's disease is quite rare, it is unlikely that a drug company would consider it a commercial opportunity.
How This May Affect Your Student At School
Many affected people move about with no assistance at all and lead independent, productive lives. The most successful students have also learned to use a wide variety of visual aids such as magnifiers, closed circuit TV readers, special bioptic glasses, etc.. It is highly recommended that a person with advanced macular degeneration enroll in a program of low vision rehabilitation. This program will provide evaluation of visual needs, assistance with environmental adaptations, and training in the use of appropriate low vision devices and computer software.
References
Facts about macular degeneration. (2010, June 26). Retrieved from http://www.nei.nih.gov/health/maculardegen/armd_facts.asp
Macular degeneration. [Web]. Retrieved from http://www.emedicinehealth.com/macular_degeneration
AMD (n.d.). Retrieved from http://www.mayoclinic.com/health/macular-degeneration Juvenile macular degeneration. (2010). [Web]. Retrieved from http://www.eyesight.org/Macular_Degeneration/Junvenile_MD/junvenile
Synptoms of macular degeneration. (2010, June 28). Retrieved from http://www.ahaf.org/macular/about/symptoms.html
Lueck, Amanda. (2004). Functional vision. Amer Foundation for the Blind.