In Vivo Imaging of Individual Retinal Ganglion Cells in Glaucoma
Vision loss in glaucoma is due to the death of a type of nerve cell in the eye that is nearly transparent and that has proven very difficult to image. We recently devised a way to see these cells in the living eye. Our project will improve this tool and develop a new one that we will use to look at these cells for the first time in people with glaucoma. This will allow us to see the earliest changes to these cells, track how they change over time, and monitor their response to treatments.
Our goal is to understand the earliest changes to the individual cells that form the optic nerve, the retinal ganglion cells (RGCs), in patients with glaucoma. To accomplish this goal, we are developing new optical systems and imaging techniques to see these cells and track them over time in the living eye. Current clinical tools lack both the resolution and the contrast needed to see these cells in the living eye. The way the eye works is that light must pass through the RGCs to reach the photoreceptors, ie, the rod and cone cells that sense light. To allow that, RGCs are nearly transparent, making them very difficult to image. We use a technology called adaptive optics that corrects the imperfections present in all eyes to achieve high-resolutionn images, and couple this with advanced methods for detecting the small amount of light that emerges from the eye to see these cells.
We are using these new tools to image the structural features of individual cells, such as the cell body and the axons of the cells, which are long fibers that extend from each neuron, together forming the optic nerve that transmits visual information to the brain. Although we know that vision loss in glaucoma is due to the death of RGCs, it is not clear what the earliest changes are that these cells undergo prior to death. Once these cells are lost we currently have no way to restore them. If we can detect the earliest changes to RGCs in glaucoma, before vision is impaired, we can provide early diagnosis and a long window of opportunity for treatments to prevent vision loss.
About the Researcher
Dr. Ethan A. Rossi is an assistant professor at the University of Pittsburgh. His research interests include the development of advanced ophthalmic imaging devices and their application to the study of human diseases such as glaucoma and age-related macular degeneration. After majoring in Brain & Cognitive Sciences at the University of Rochester, Dr. Rossi worked at the Smith-Kettlewell Eye Research Institute in San Francisco before beginning his graduate studies at the University of California, Berkeley. Dr. Rossi received his PhD under the mentorship of Austin Roorda. After completing his PhD, Dr. Rossi returned to the University of Rochester, where he completed postdoctoral training under the mentorship of David Williams. Dr. Rossi started his own laboratory at the University of Pittsburgh in the summer of 2016.
My interest in vision science was sparked as an undergraduate when I took my first sensation and perception course. I was fascinated by how much of the brain was devoted to this most central of our sensory capabilities, and at that point we knew little about how the whole system worked. As a graduate student, I began using advanced optical techniques to study the limits of vision, and it was during that time that I realized how much our understanding of vision could be improved by studying how it is altered because of disease. My goal over the past several years has been to adapt new advanced optical imaging technologies to the study of human diseases, and where we lack tools to study specific aspects of human vision diseases, to develop new ones to fill in the gaps. The entire field of ophthalmic imaging has been moving ahead rapidly in the past several years.
As each new year passes we have a new method, or several methods, to image new classes of cells that had previously been inaccessible. As the focus of our field has shifted recently towards vision restoration, it is my hope that we can use these tools to evaluate the efficacy of these new vision restoration approaches and use them to detect diseases at the earliest of stages in order to intervene early with new treatments that may prevent vision loss from occurring at all.
First published on: August 24, 2017
Last modified on: August 19, 2020