Malcolm Slaughter, Ph.D., SUNY at Buffalo Multiple roles for GABA Receptors in Retinal Information Processing GABA is the primary inhibitory transmitter in the brain. At least five GABA receptors have been identified in retina, making this tissue the model system for linking receptor diversity with physiological significance. It appears that each receptor regulates an aspect of our visual processing. The human eye accommodates readily to changes in the vergence of light, but the optical signals and mediating mechanisms are obscure. As a consequence of chromatic aberration, comparison of cone-contrasts distinguishes myopic from hyperopic focus.
Experiments explore both chromatic and achromatic aspects of the process.
Accommodation is not mediated by the average Stiles-Crawford effect, but local variations in cone orientation might play a role. Besides accommodation, sensitivity to light vergence is important for emmetropization. Some patients with visual impairments may require very large letters to read at all, and if scotomas are present in the visual field they may have difficulty in navigating around a full page of text. Optical or electronic magnification of printed text is limited in addressing these problems. A system has been developed that allows persons with very bad acuity to read at unprecedented rates.