What is Macular Degeneration?
Macular degeneration (AMD) is the leading cause of vision loss and blindness in Americans 65 years and older. Because of the affected age group, macular degeneration is often referred to as age-related macular degeneration (AMD).
Macular degeneration affects the macula – the part of the retina responsible for sharp, crisp, clear vision used for reading and driving, and damage to this area of the retina results in loss of central vision.
Forms of Macular Degeneration
Macular degeneration is diagnosed as either non-neovascular (dry) or neovascular (wet). Neovascular refers to the growth of new blood vessels in an area (such as the macular) where there shouldn’t be growth.
Dry Macular Degeneration (non-neovascular) is an early stage of the disease and may result from thinning of the macular tissues or pigment deposits in the macula, or a combination of both.
Usually, diagnosis is made when yellow spots called drusen begin to form from deposits of deteriorating tissue. Central vision loss may occur gradually, but not as severely as wet AMD.
While there is no FDA-approved treatment for dry AMD, studies show that certain nutrients such as vitamins A, C and E may prevent it or slow its progression. Optometrists recommend wearing sunglasses to protect against harmful UV radiation from the sun.
Wet Macular Degeneration (neovascular) is the more advanced and damaging form of AMD. Roughly 10% of dry AMD progresses to wet AMD.
Wet AMD is characterized by the growth of new blood vessels which eventually lead to blood and protein leakage below the macula and scarring. Left untreated, the leaking and scarring will cause irreversible damage to the photoreceptors and rapid vision loss.
Symptoms
Symptoms of AMD are usually slow and painless, and include:
- Blurred vision
- Central scotomas (shadows or missing areas of vision)
- Distorted vision
- Trouble discerning colors
- Slow recovery of vision after exposure to bright light
- A loss in contrast sensitivity
One of the simplest methods of testing for macular degeneration is an Amsler Grid Test. The test consists of a grid of evenly spaced black lines with a single black dot in the middle. Normal vision will show all lines round the dot as perfectly straight and at 90 degree angles to each other. Macular degeneration causes these lines to appear bent and wavy and there may be areas of the grid that are completely missing.
Based on the Amsler test, it isn’t surprising that many cases of macular degeneration are diagnosed after people notice distortions when looking at mini-blinds. To try the Amsler Grid Test click here.
Prevention As with many eye disorders, doctors recommend that a diet rich in the antioxidants vitamins A, C and E can lower the risk of developing macular degeneration. The nutrients zinc, lutein, and zeaxanthin may also help in this regard. Risk factors that may or may not be avoidable are: obesity, hypertension, smoking, lighter eye color, aging, and heredity.
Treatment Currently there is no treatment for dry AMD. Treatments for wet AMD include laser treatment and photodynamic therapy. Complete recovery from loss of vision is highly unlikely and, in most cases, the only treatment is low vision enhancement aids like magnifying glasses. Some aids even shift images from central to peripheral vision.
If you notice any of the above symptoms, or have anomalous results when viewing the Amsler Grid Test, consult your optometrist or ophthalmologist immediately.
