Blindness caused by age-related macular degeneration affects more than two million people in the United States. The eye disease can lead to progressive loss of central vision and significantly affect quality of life. Unfortunately, there is no known cure for the disease.
Macular degeneration is caused by the deterioration of the central portion of the retina. This is the inside back layer of the eye that records images and sends them via the optic nerve from the eye to the brain. The retina’s central portion, known as the macula, is responsible for focusing central vision in the eye, and it controls the ability to read, drive a car, recognize faces or colors, and see objects in fine detail. When the retina becomes deteriorated, it can no longer function properly, and can eventually lead to blindness.
Although there is no known cure, there are a limited number of effective long-term treatments available for two forms of macular degeneration. The wet form is caused by growth of abnormal blood vessels under the macula. This can be alleviated by regular injections in the eye from an ophthalmologist.
The dry form of the disease is marked by accumulations of yellow deposits called drusen which form in the macula. Unfortunately, there is no treatment for this form other than eye vitamin supplements. Other than providing some benefits, over time, there can be a continued progressive loss of vision in both forms of the disease, even with treatment.
Three Dozen Genes Identified
Genome studies have identified almost three dozen genes that play a role in age-related macular degeneration, but it is still unknown where in the eye exactly they inflict damage. This is what researchers from Yale University, the Broad Institute of the Massachusetts Institute of Technology, and Harvard University set out to discover in the study published in the journal Nature Communications. The study found that glial cells (or support cells) and vasculature cells tasked with providing blood to the retina as well as cone cells contribute to the degeneration of the macula, in the central part of the retina.
“This study helps pinpoint cell types that can be investigated closely to develop new types of therapeutics,” said co-senior author Brian Hafler, assistant professor of ophthalmology and visual science and of pathology at Yale.
For the study, the research team used new single-cell sequencing to generate the first comprehensive human retinal atlas and adopted data analysis technology to localize their effects on specific cell types connected to the disease.
Although these genes have now been identified and associated with cones, which is the cell type key to central vision, they also found a link with glial and vascular cells. This may provide possible targets for therapies to improve and help to restore vision before blindness occurs.