Optoretinography: Technology, mechanisms & applications
Abstract
Photoreceptors initiate vision by converting photons to electrical activity via the process of phototransduction. Recent developments in high-resolution imaging have allowed characterizing the biophysical correlates of cone phototransduction in a living human eye. Specifically, our lab has used high speed phase-resolved optical coherence tomography that provides sufficient spatiotemporal resolution to visualize nanometer/millisecond-scale shape changes in photoreceptor outer segments in response to light. With adaptive optics, it is now possible to quantify such light-driven changes in individual human cone outer segments’ (COS) length, affording a non-invasive, label-free, functional assay of cone viability. Such optical recording of light-evoked responses in the retina is generally referred to as optoretinography (ORG). This talk will first describe our high-resolution imaging technology platforms that enable the ORG recordings in vivo. Next, it will review the mechanisms in photoreceptors that underlie their ORG responses to light stimuli. Finally, the talk will describe applications of ORG to study the spectral topography of the human cone mosaic and photoreceptor dysfunction in patients with retinal disease. Together, these studies provide a basis for the assessment of photoreceptor function in health, during disease progression and therapeutic interventions.
Biography
Ramkumar Sabesan earned his Bachelor’s degree in Engineering Physics from the Indian Institute of Technology, Delhi and his Ph.D. in Optics at the Institute of Optics and Center for Visual Science at the University of Rochester. He did a postdoctoral fellowship at the School of Optometry at University of California, Berkeley studying the retinal basis of color perception using advanced high-resolution imaging, before joining the faculty at University of Washington's Department of Ophthalmology. At UW, Dr. Sabesan holds adjunct appointments in the departments of Bioengineering and of Biological Structure, and is a member of the Graduate program in Neuroscience and University of Washington Institute for Neuroengineering. The Sabesan Lab’s basic vision science and translation research questions are centered around the ability of ophthalmic adaptive optics to provide in vivo cellular scale access to the visual system for physiological and psychophysical assays. He has received several awards including the Burroughs Wellcome Fund Careers at the Scientific Interfaces Award, Research to Prevent Blindness Career Development Award, Alcon Research Institute Young Investigator Award, and being named a Kavli fellow by the National Academy of Sciences.