Age related macular degeneration (AMD) is a condition that affects the macula. The macula is the central part of the retina which lines the back of your eye; the macula is therefore vital for central vision. With AMD, the macula becomes damaged and this causes problems with your central vision and visual acuity.
In a normal eye, light entering the eye becomes focused onto the retina. The retina is the innermost layer of the eye which converts the light into biochemical signals. These signals are then transmitted to the brain through the optic nerve. At the center of the retina is the macula, which is about the size of a pinhead. It is a specialized area of the retina that contains a few million specialized photoreceptor cells (cones). The cone photoreceptors at the macula function best in bright light, and are important for seeing fine detail, such as in reading and writing, and also for recognizing colors.
In AMD, only the macula and its cone photoreceptors are damaged while the rest of the retina remains relatively unaffected. Hence, while macular degeneration affects your central vision, it does not cause total loss of sight.
AMD causes problems when you are looking directly at something, such as when reading or watching television. Your central vision may become distorted or blurry and may eventually turn into a blank patch.
Well, you may experience the following symptoms in one or both eyes:
– Difficulty reading small print
– Difficulty recognizing faces
– Distortion or waviness of straight lines
– Increased sensitivity to bright light
– Noticing shapes/lights that are not there
– Blank patch in the field of vision
– Blurred area in the central vision
The visual impairment caused by age-related macular degeneration may or may not be reversed, depending on the type and severity of damage. This means that blindness from AMD may be permanent. Early detection and treatment is therefore vital.
Treatment options depend on whether the age-related macular degeneration is dry (atrophic) or wet (exudative).
At the moment, no treatment is available for dry AMD. In dry (atrophic) AMD, the cone photoreceptors cells at the macula essentially degenerate and ‘die’. There are no abnormal blood vessels, and hence there is no accumulation of blood or fluid at the macula. However, there may be deposits of retinal waste products called drusen. Research is ongoing, but nothing has been found to be able to effectively stop this atrophic process thus far.
In wet (exudative) AMD, there is growth of abnormal blood vessels at the macula. These abnormal blood vessels (choroidal neovascularization) cause leakage of blood and fluid which disrupts the normal structure and function of the cone photoreceptors. The normal visual function of the macula can be regained if the blood and fluid is cleared from the macula. The aim of treatment is therefore to stop these abnormal blood vessels from growing.
This can be achieved with injections of anti-vascular endothelial growth factor (anti-VEGF) drug into the vitreous cavity in the eye. Anti-VEGF treatment is usually very effective in stopping the growth of the abnormal blood vessels. In circumstances where anti-VEGF injections may be inappropriate or insufficient, photodynamic therapy may be considered. Photodynamic therapy (PDT), is a type of laser treatment which combines a light sensitive drug and a low energy laser to the macula.
The chances of success from treatment are highest when treatment is started early.
Further information on macular degeneration can be found here:
Eye News : link to eye news article on Macular Degeneration
Vision Eye & Health: http://www.vision-and-eye-health.com/macular-degeneration.html