21 Feb Geographic Atrophy
Geographic is a form of dry ARMD.
There are two situations where macular degeneration causes severe vision loss; wet macular degeneration and geographic atrophy.
Wet macular degeneration is characterized by the growth and development of abnormal blood vessels (neovascularization) within the different layers of the retina. Wet ARMD is treated with anti-VEGF agents such as Avastin and Lucentis.
Geographic atrophy is technically a severe form of “dry” macular degeneration (no neovascularization) where no blood vessels are growing, yet the middle layer of the retina (the RPE – retinal pigment epithelium) degenerates.
If you look at the pics, these areas are depicted by the large pale/white central areas. The areas are whiter due to the absence of this RPE – the pigmented cells.
When viewing the retina, pretend you are looking through 3 pieces of stained glass. The result is a homogeneous color resulting from the colors of the 3 pieces of glass.
In geographic atrophy, the middle piece of “glass” is removed resulting in a strikingly different color in the area which is defective.
Severe Loss of Vision
Severe vision loss results when the macula is involved. In this particular case, neither eye has good central vision as the atrophic (diseased) area involves the entire macula. This may have taken 10-20 years or more to reach this level. Geographic is slow and insidious.
Treatment for Geographic Atrophy
There is no treatment for geographic atrophy. While central vision is lost, peripheral vision remains intact.
Vitamins (AREDS formula) may be helpful in slowing down the progression. AREDS formula vitamins are recommended for patients with geographic atrophy.
Laser treatment is of no use, nor is anti-VEGF therapy. Both target new blood vessel formation (stop neovasculurization).
What Does this Mean?
Geographic atrophy develops slowly. There is little we can do to slow down the progression and nothing we can do to improve vision.
The CentraSight Telescope may be used in certain situations. Though FDA approved and covered by Medicare, there are few centers offering implantation and the criteria for patient eligibility are strict.
Vision Care markets the CentraSight in the U.S.
Geographic atrophy may eventually be treatable with stem cells; replacing the diseased areas of the RPE with healthy news cells derived from the stem cells.
If you have evidence of geographic atrophy, only your doctor can evaluate its severity and progression.