The Form and Function of Retinal Ganglion Cells in Diabetes

This review examines how diabetes affects the ganglion cells of the retina, including the axons that make up the optic nerve. Links between established changes in the morphology of retinal ganglion cells (RGCs) and vision loss, as well as other functions, such as the pupillary light reflex, are considered. RGC morphology and function are significantly altered in both animal models and humans with diabetes. Diabetes affects all parts of the RGC, including the dendrites, the cell body, the axons making up the nerve fiber layer, and the optic nerve. Subtypes of RGCs appear to be affected differently by diabetes, and the morphology and electrophysiological output are more significantly affected in ON-RGCs than in OFF cells, which may explain part of the mechanism underlying the widely documented diabetes-induced reduction in contrast sensitivity. Furthermore, the morphology of the specialized light-sensitive melanopsin-containing RGCs also appears to be affected by diabetes, which may explain deficits in circadian rhythm and the pupillary light reflex. Potential therapeutic approaches aimed at protecting RGCs in diabetes are also discussed. Overall, strong evidence supports the conclusion that diabetes impacts the form and function of RGCs and their axons within the optic nerve, resulting in deficient regulation of circadian rhythms and the pupillary light reflex, in addition to vision.