Intrinsic signal optoretinography of dark adaptation abnormality due to rod degeneration

Significance: Multiple eye diseases such as age-related macular degeneration, diabetic retinopathy, and retinitis pigmentosa can cause photoreceptor dysfunction. Rod photoreceptors are known to be more vulnerable than cone photoreceptors. Therefore, functional assessment of rod photoreceptors is important for early detection of eye diseases. Aim: This study is to demonstrate the feasibility of using intrinsic optical signal (IOS) optoretinography (ORG) for objective detection of dark adaptation (DA) abnormality due to rod photoreceptor degeneration. Approach: Functional optical coherence tomography (OCT) was employed for IOS ORG of wild-type (WT) and retinal degeneration 10 (rd10) mice. Six WT C57BL/6J and eight rd10 B6.CXB1-Pde6brd10/J mice at postnatal day 14 (P14) were used for this study. Dynamic OCT analysis of retinal thickness and brightness changes, corresponding to light to dark transition, was implemented Results: Comparative measurement of the retina under light and dark conditions revealed significant IOS changes within the outer retina. The thickness between external limiting membrane (ELM) and retinal pigment epithelium (RPE) reduced, and the OCT brightness of inner segment ellipsoid zone (EZ) decreased during DA, compared to light adaptation (LA). Relative EZ intensity change was observed to decrease larger in rd10, compared to WT. The relative intensity of the hyporeflective band between ELM and RPE also showed significant decrease in rd10 retinas during DA. Conclusions: DA-IOS abnormalities were observed in rd10, compared to WT at P14. The ORG measurement of DA-IOS kinetics promises valuable information for noninvasive assessment of photoreceptor function.