Abstract
Purpose :
To measure the photoreceptor response in rodent eyes using phase-sensitive optical coherence tomography (OCT)To measure the photoreceptor response in rodent eyes using phase-sensitive optical coherence tomography (OCT)
Methods :
Six Brown-Norway rats (age = 6 weeks) were used for this study. The animals were dark-adapted for 12 hours before being anesthetized using a cocktail of ketamine and xylazine. They were placed on a translational stage with 5 degrees of freedom, and the head was stabilized stereotaxically. A customized spectral-domain OCT system (central wavelength = 840nm, bandwidth = 145 nm) was applied to image the posterior eye, with a field of view of 20 degrees. A single cross-sectional position was traced temporally for 5 seconds, and at t = 1 second, a single 1ms visual stimulus (wavelength = 500 nm) was delivered to create a large and Maxwellian illuminance on the retina. The temporally sequenced cross-sectional OCT scans were registered, and the hyperreflective bands from inner segment and out segment of the photoreceptors were segmented automatically. The phase difference between the two layers was computed and traced over time.
Results :
Visual stimulus-evoked nanoscopic photoreceptor response can be detected by phase-sensitive OCT, which is reproducible over different spatial locations on the retina (intra-class coefficient = 0.84). Stimuli with a bleach rate of 0.3% were associated with a transient optical path length change of 48.2 ± 16.4 nm. Signals from underneath retinal blood vessels decorrelated over time, likely due to the influence of the blood flow.
Conclusions :
Phase-sensitive OCT provides a novel non-invasive approach to study photoreceptor response in rodents, and the current framework could be applied to investigate different animal disease models with photoreceptor abnormalities.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.