Macular Degeneration Gene Opens Eyes to New Treatments
July 02, 2007
By: Allison Tsai for Body1
The recent discovery of the gene HTRA1 may help people see into their future. A simple blood test can determine whether a person is at a 700 percent greater risk of developing Age-Related Macular Degeneration (AMD), according to researchers at the John A. Moran Eye Center at the University of Utah.| Take Action | According to the National Eye Institute, symptoms of wet and dry AMD include:
Dry:
Blurred vision
Trouble reading/watching TV/seeing details
Blurriness that goes away in brighter light
A blind spot
Wet:
Distortion of straight lines
Small blind spot in central vision
Both types are painless. |
The discovery, lead by Kang Zhang M.D., Ph.D, Director of the Division of Ophthalmic Genetics and Associate Professor of Ophthalmology and Visual Sciences at the University of Utah, identifies a mutant copy of the gene, which means at-risk people might be able to change lifestyle habits and lower their risk of – or delay the onset of – AMD.
Though the research is promising, studies proving lifestyle changes can lower risk are a long way off, says Dr. Thomas Hull, an ophthalmologist of The Retina Group of Northeast Ohio. “It is age-related and typically takes years and years to develop. So it is hard to say, because you would have to follow people for an inordinate amount of time to do a study.”
There are still advantages to having the blood test, says Hull. “If you were predisposed to AMD, you could go to regular check-ups, take the high-dose antioxidant vitamins to see if they help, and avoid cigarette smoking, because we already know that causes AMD.”
Age-Related Macular Degeneration affects patients older than 60, and is considered the leading cause of blindness in the developed world. There are two types of macular degeneration, wet and dry, says Hull. “Dry is far more common, but severe vision loss happens with wet.”
The disorder affects the macula, which is the center of the retina responsible for clear vision. Sometimes, byproducts deposit underneath the retina. Through a little break, blood vessels start growing into the area, which prevents the retina from functioning properly, says Hull. “Blood vessels grow in like weeds, and it causes vision loss.”
Symptoms of AMD include distortion of straight lines, blurred vision, difficulty reading, watching television and seeing faces. “If you look at a window pane or doorframe and they look bent, it’s distorted,” says Hull. “It looks that way because there is fluid in there.”
The discovery of this HTRA1 gene may also lead to new treatments in the distant future. There have already been dramatic improvements in AMD treatment in the past 10 years, says Hull. “Eight or nine years ago, the only treatment was to cauterize the blood vessels with a thermal laser, but that destroyed the overlying retina so the patient would have a very dense spot in their vision.”
Then about six years ago, they developed a non-thermal laser. The laser has a dye that causes a chemical reaction within the eye to close the vessels, says Hull. Within the last two years, an entirely new approach was implemented. Medicine is now injected directly into the eye with a needle to stop vessel growth. “It used to be that you could only treat patients to maintain stabilization, but after these meds, there was a 40 percent improvement,” says Hull.
With the discovery of the AMD gene, the future of preventive treatment is wide open. Once genes are identified, treatments that genetically alter these risks could be developed, says Hull. “In the future they may be able to address the problem before it even starts.”
Last updated: 02-Jul-07
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