Abstract
Presentation Description :
In vivo cellular-scale imaging of retinal structure and function is needed to better understand, diagnose, and develop treatments for disease. With the aid of adaptive optics, retinal cell morphology and cellular mosaics in the living eye can be visualised. Two-photon excited fluorescence (TPEF) imaging has the potential to reveal cellular structure and function as it probes molecules involved in the visual cycle and cellular metabolism. Using TPEF combined with adaptive optics scanning light ophthalmoscopy in the living non-human primate eye, we have visualized several cell types, including ganglion cells and photoreceptors. In response to a visual stimulus, the time course of emitted TPEF intensity from photoreceptors is related to the behavior of the visual cycle. Fluorescence lifetime adds another dimension because it varies with cellular function and fluorophore composition. It is a measure of the time delay between fluorescence excitation and emission. In macaque, we have observed that S cones, M/L cones and rods have different fluorescence lifetime properties, indicating functional differences in their fluorophore composition, a result not previously observed in ex vivo retina. By comparing fluorescence lifetime signatures throughout the retina to those of known fluorophores, we are establishing a basis to assess multiple molecular pathways within the retina. The fluorescence lifetime signatures are consistent with known inner retinal metabolites, photoreceptor outer segment retinoids and vascular elastin. In vivo TPEF adaptive optics fluorescence lifetime ophthalmoscopy (AOFLIO) may provide a means to distinguish specific molecular differences in healthy compared to unhealthy cells and provide insight into the composition and mechanisms of the intracellular changes that occur with age and disease.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.