Feature Of The Week 03/01/2019: Functional Retina lmaging using Adaptive Optics Swept-Source OCT at 1.6 MHz
Functional assessment of the retina is a critical part of both clinical ophthalmology and vision research. Several techniques exist for measuring retinal function, such as Visual acuity/contrast sensitivity tests, Psychophysics and ERG (Electroretinogram and multifocal Electroretinogram). However, these approaches have important limitations, poor spatial resolution, slightly invasive; long duration of tests.
There is great excitement about emerging noninvasive approaches to measuring retinal function, both from clinical and basic scientific perspectives .With emerging approaches such as gene therapy, stem cell therapy, and transplantation, there is new hope for rescuing existing dysfunctional photoreceptors. A critical aspect of these therapeutic approaches is assessing their efficacy, and functional imaging at the cellular level would be a great way to do this.
In this work, we describe an adaptive optics (AO) optical coherence tomography (OCT) system designed to measure functional responses of single cones to visible stimuli. The OCT subsystem consisted of a raster-scanning Fourier-domain mode-locked laser that acquires A scans at 1.64 MHz with a center wavelength of 1063 nm and an AO system operating in closed-loop. Analysis of serial volumetric images revealed phase changes of cone photoreceptors consistent with outer segment elongation and proportional to stimulus intensity, as well as other morphological changes in the outer segment and retinal pigment epithelium.
For more information see recent Article. Courtesy Mehdi Azimipour from University of California Davis.