The causes behind vision loss from conditions such a macular degeneration and diabetic retinopathy are complex and are not just one thing but a cascade of cellular and genetic actions that lead to blindness for millions of people.
What if there was a way to stop the negative cascade from happening and preserve vision? Thanks to two separate research projects, one at the University of Virginia and the other at the University of Utah, show that it is possible to either stop the cascade or prevent it from happening in the first place.
At the University of Virginia scientists found that a group of HIV drugs may prevent macular degeneration. The drugs known as Nucleoside Reverse Transcriptase Inhibitors (NRTIs) have shown to be useful against dry macular degeneration, even though it is not a viral condition.
The scientists learned that the buildup of a type of DNA in the cytoplasm, known of Alu contributes to macular degeneration. This buildup kills an important layer of cells that nourishes the visual cells in the retina. As a result of this discovery, researchers decided to look at drugs that block the production of DNA to see if it can prevent vision loss. They evaluated more than twenty years’ worth of information that was contained in four health insurance databases. These databases had information on more than 100 million patients and the researchers found that those who took NRTIs were 40 percent less likely to develop dry macular degeneration.
Scientists are recommending that additional studies be done to see if NRTIs or safer derivatives known as Kamuvudines, which both block a key inflammatory pathway, can prevent vision loss from dry macular degeneration.
Another research project is looking at lipids, specifically if giving a certain type of lipid to a patient could help to maintain vision in cases of age-related macular degeneration, diabetic retinopathy, and some inherited retinal diseases. Known as very-long-chain polyunsaturated fatty acids (VLC-PUFAs) these could be given as a supplement to patients.
While this is made in the body, the VLC-PUFAs were not available in quantities large enough for research, so scientists as the University of Utah developed a method to synthesize large quantities of VLC-PUFAs to assess their sight-preserving properties. This study showed that a VLC-PUFA supplement increased lipid levels in the retina and improved visual function in both normal mice and mice with a defect in the ELOVL4 enzyme, which makes the VLC-PUFA.
Of course, more work is needed. Still, these results raise important questions about how the orally administered VLC-PUFAs improve vision, how they are carried in the bloodstream and how they are targeted to the retina. It’s formulation, dosage and timing need to first be optimized. Once that happens, the VLC-PUFAs mechanisms need to be defined. Researchers are confident that the new synthetic method will enable them to both synthesize and study other VLC-PUFAs variants and get a better idea how what each of them do.
Like an onion, research shows that there are many layers to the cellular and genetic actions that lead to vision loss. Over time scientists peel back the layers and their findings lead to treatments that improve outcomes.