New Retinal Imaging Technique Could Revolutionize Eye Care

A new study describes a non-invasive method to image individual cells in the human retina, which are implicated in the vision loss associated with glaucoma and other diseases.

Researchers at the University of Rochester, the University of Pittsburgh School of Medicine, and other institutions modified adaptive optics scanning light ophthalmoscopy (AOSLO) in order to successfully image somas of neurons within the retinal ganglion cell (RGC) layer in both monkeys and humans. They also showed that the same technique, when applied to the photoreceptor layer, could resolve ambiguity about cone survival in age-related macular degeneration (AMD).

The researchers reported that while currently, the human images did not match the quality of monkey images for safety reasons involving light intensity, the capability to noninvasively image RGC layer neurons in the living eye may one day allow for a better understanding of diseases such as glaucoma, and accelerate the development of therapeutic strategies that aim to protect these cells. This method may also prove useful for imaging other structures, such as neurons in the brain. The study was published on December 6, 2016, in Proceedings of the National Academy of Sciences (PNAS).

“Retinal ganglion cells are the primary output neurons of the retina that process visual information and transmit it to the brain. The death of these cells causes vision loss in glaucoma, the second leading cause of blindness worldwide,” concluded lead author Ethan Rossi, PhD, assistant professor of ophthalmology at Pitt. “The ability to image these cells in the living eye could accelerate our understanding of their role in normal vision and provide a diagnostic tool for evaluating new therapies for retinal disease.”

Although imaging of the living retina with AOSLO provides access to individual photoreceptors, retinal pigment epithelial cells, blood cells in the retinal vasculature, and RGCs, have proven much more challenging to image. The near transparency of inner retinal cells is advantageous for vision, as light must pass through them to reach the photoreceptors, but it has prevented them from being directly imaged in vivo. As a result, glaucoma is currently diagnosed by assessing the thickness of the nerve fibers projecting from the RGCs to the brain.