Researchers have found the types of cells in the eye that are linked to blindness in old age -- an advance that may lead to novel drug targets for treating age related loss of vision. The study, published in the journal Nature Communications, noted that three different cell types contribute to degeneration of the macula -- the central part of the eye's retina: Glial cells that support and insulate nerves, and vascular cells tasked with providing blood to the retina, as well as cone cells that help the retina detect light.
The researchers, including those from Yale University in the US, used a new single-cell genome sequencing technique to generate the first ever comprehensive map of genes expressed in the human retina, and narrowed down to the pattern of gene activity in specific cell types associated with the disease.
"This study helps pinpoint cell types that can be investigated closely to develop new types of therapeutics," said co-senior author Brian Hafler from Yale University. The researchers said that age-related macular degeneration is one of the leading causes of blindness in the elderly, leading to progressive loss of central vision.
They added that while genomic studies identified almost three dozen genes involved in the disease, the exact location in the eye where the damage was inflicted was not well known. The study noted that there are two forms of macular degeneration: The wet form, caused by growth of abnormal blood vessels underneath the macula, and the dry form of the disease marked by accumulations of yellow deposits called drusen in the retina's central region.
According to Hafler and his team, a limited number of effective long-term treatments are available for treating both the forms. The wet form, they said, can be mitigated by regular drug injections in the eye.
And for the dry form there are no treatments other than eye vitamin supplements, the researchers said. Even when the current treatment options provide some benefits, the researchers said that there can be a continued, progressive loss of vision in both forms of the disease.
The researchers have found the risk genes associated with cones -- the cell type key to central vision, and have also found an association with glial cells that surround and insulate nerves, and vascular cells that carry blood. The findings, the study noted, can lead to possible targets for novel therapies to improve and restore vision.