Abstract
Purpose :
To present updated interpretation and modeling of the origins of the light evoked functional retinal imaging with Optical Coherence Tomography. To endorse use of term Optoretinogram (ORG) for NIR OCT based measurements of bleaching-induced changes in the retinal morphology in vivo.
Methods :
Dark adapted albino (Balb/c) mice were imaged in vivo with a custom SLO / OCT retinal imaging system. In order to alter light evoked retinal response, we induce a mild, diffuse central retinal edema by intraperitoneal (IP) injection of distilled water at 20ml/kg and 40 ml/kg body weight. Mice retinas were imaged with OCT before and after the injections to monitor water movement through the retina as it changed over time. At about 12 minutes after water injection we applied our standard protocol to measure ORG signals (time-dependent changes of the depth scattering profiles of retinal layers).
Results :
Figure 1 shows ORG signal (light-evoked changes) from Photoreceptor RPE Choroid – Neurovascular Unit (PRC-NVU) in Balb/c mice at baseline and 15min after water injections. The depth scattering ORG profiles extracted from the OCT data reveal correlations between depth positions and intensity of different outer retina bands. The comparison between ORG responses during mild, diffuse central retinal edema and normal retina without water injection shows several changes in kinetics of the retina layers swelling as well as OCT scattering. These results also prove that relatively simple alteration in retinal water homeostasis could have an important impact on retinal function.
Conclusions :
Changes in the ORG signals caused by a mild, diffuse central retinal edema further confirm the water movement between different compartments of the outer retina as origin of measured ORGs. The results also suggest much faster diffusion of water between the choroid and SRS as compared to SRS into ROS. The use of “ORG” term draws an instructive parallel to the ERG (electroretinogram), which has long been used to assess retinal function in vivo. Specifically, the ORG, like the ERG, comprises multiple components arising from distinct cells and mechanisms. Moreover, both ERG and ORG require an explanation in terms of the underlying cellular and molecular mechanisms to achieve their full scientific and clinical utility.
This is a 2020 ARVO Annual Meeting abstract.