CLARKSBURG, Md., Nov. 9 (UPI) -- Investigating why people with Parkinson's disease taking the drug L-DOPA appear protected from developing age-related macular degeneration, or AMD, researchers found the drug may be able to delay or prevent the vision-taking condition.
AMD is the progressive damage of the macula, an area near the center of the retina used for sharp, central vision. Over time, blurred areas starting in the middle of the macula and growing outward make it difficult to complete everyday activities, even if it does not lead to blindness.
Previous research has shown people with darker pigmented eyes, which resist the development of AMD, have higher levels of L-DOPA, an amino acid that is a precursor to dopamine, in their eyes. Based on this, the researchers sought to find out if Parkinson's patients who are prescribed L-DOPA -- with the goal of increasing dopamine levels in the brain -- had a similar effect on their eyes as it does for people with naturally higher levels.
"Rather than looking at what might cause AMD, we instead wondered why certain people are protected from AMD," Dr. Brian McKay, a researcher at the University of Arizona, said in a press release.
The researchers reviewed medical records for 37,000 patients at Marshfield Clinic in Wisconsin. While the average age of patients prescribed L-DOPA is 67, the average age of AMD diagnosis is 71, allowing the researchers to track differences and patterns among patients.
Looking at three separate groups of patients, the average age of AMD onset was 71.2 years, 71.3 years, and 71.3 years, while AMD was diagnosed among patients taking L-DOPA much later in all the studies -- on average, around age 79.4.
The researchers said the data indicates L-DOPA could help to at least delay AMD with plans to launch a clinical trial to further test this specific use for the drug.
The study is published in the American Journal of Medicine.