Walk down any pharmacy aisle and you will find shelves of fish oil capsules promising to protect your eyes. The active ingredient is almost always DHA, an omega-3 fatty acid found in oily fish. However, a new study from the University of California, Irvine suggests that bottles are aiming at the wrong molecule.
Researchers led by Dorota Skowronska-Krawczyk reported that a single injection of a different fatty acid called 24:5n-3 restored visual function in aged mice. DHA on its own did nothing. The findings, published in Science Translational Medicine, point to a possible new treatment for age-related macular degeneration, the leading cause of vision loss in older adults.
The compound 24:5n-3 is produced by ELOVL2, a gene scientists use as one of the body's most accurate molecular clocks. Levels of these fatty acids fall as the retina ages, and that decline appears to cause fading sight.
The researchers delivered the fatty acid directly into the eye using an intravitreal injection. Mice ranging from 3 to 23 months old were studied. The results were measurable across three separate vision tests. A single injection improved visual function for up to four weeks. The retinas of treated animals also looked younger under inspection.
DHA, given the same way, did not produce these effects. The team also examined human genetic data and identified variants in the ELOVL2 region linked to faster onset of intermediate age-related macular degeneration. Although the study was conducted in mice, it suggests that the retina loses a specific ingredient with age, and replacing it may help restore vision.