Researchers zero in on potential dry AMD treatment

December 3, 2015
An approved treatment for wet AMD might also improve the more common dry AMD.

A new study identifies a potential therapeutic target for the dry form of age-related macular degeneration (AMD), as reported in Investigative Ophthalmology & Visual Science, a journal of the Association for Research in Vision and Ophthalmology (ARVO).

AMD is the leading cause of severe irreversible vision loss in adults older than 50 in the United States, and there is limited treatment. The Centers for Disease Control and Prevention estimate that 1.8 million people have AMD and another 7.3 million are at substantial risk for vision loss from AMD.

Researchers zeroed in on placental growth factor (PIGF), part of the vascular endothelial growth factor (VEGF) family. Past studies show that PIGF is implicated in the progression of wet AMD and blocking PIGF has a therapeutic effect. An anti-PIGF injection called aflibercept (Eyelea®) is an approved wet AMD treatment.

The study authors thought the opposite was true for dry AMD. They had previously shown that injecting PIGF into retinal cells in mice in vitro reduced light-induced damage, but the newest study contradicted this.

After injecting mice with PIGF before and after exposure to intense light, a procedure that induces dry AMD-like conditions, the research team was surprised to learn that PIGF made the retinal damage and thinning of the retina worse. Therefore, they decided to inject the mice with anti-PIGF before light exposure and discovered that the breakdown of the retinal pigmented epithelium was suppressed, thus somewhat protecting the retinal cells from damage. PIGF may be a good target for anti-PIGF treatments in dry AMD as well.

"We know anti-VEGF has a place in retinal degeneration diseases ... but this research shows it is also protective—that's the key," says Andrew Morgenstern, O.D., chair of AOA's New Technology Committee and a consultant with Booz Allen Hamilton whose current assignment is with the Vision Center of Excellence at Walter Reed National Military Medical Center in Bethesda, Maryland.

Because aflibercept is an anti-PlGF antibody, the research team thinks it might work for dry AMD as well. "Using an existing drug in clinical trials could shave years off the time needed to determine if an anti-PlGF treatment could address dry AMD, an encouraging prospect for those suffering from the slow, currently untreatable vision loss resulting from the condition," according to an ARVO news release.

The mechanism for how anti-PIGF works is complicated and further research to clarify the process is needed, says Sue Lowe, O.D., chair of the AOA Health Promotions Committee who practices in Laramie, Wyoming. "This is very technical, but it seems that's where research is going now. I am fascinated by these articles—who knows what's on the horizon."

The AOA follows all research and new technology closely, including potential dry AMD treatments. Although anti-PIGF is an interesting treatment for patients, more research is needed regarding its influence on visual health. For more information or help for better vision, please visit the AOA's diet and nutrition page.

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