Abstract
Purpose :
Functional characterization at cellular resolution is key to the advancement and evaluation of new therapeutic interventions such as gene and cell replacement therapies. Here, we report development of optical coherence tomography (OCT) guided micro-focal multi-color light stimulated electroretinogram (ERG) platform for highly localized monitoring of retina function. Functional evaluation of wild type and animals with degenerated retina was carried out using OCT guided micro-focal ERG (μfERG) with selected stimulation wavelengths for S, M and L cones as well as rod photoreceptors.
Methods :
The stimulation light beam was fiber coupled and combined with the OCT imaging beam. Using Nanoscope Instrument’s NS-Neel OCT guided μfERG platform, μfERG responses from different retinal locations were recorded. Light flashes were elicited by pre-selected wavelengths (Blue: 455 nm; Green: 530 nm; and Red: 630 nm) of the micro-focused beam on wild type mice and pigs as well as animals with photoreceptor degeneration caused by gene mutation or laser-injury. Micro-focal ERG from multiple strobe light flashes were averaged and filtered to obtain the final waveform.
Results :
Functional deficits in mice and pigs with photoreceptor degeneration was observed via micro-focal ERG measurements. Further, μfERG recordings from different types of cones produced unique characteristic responses when stimulated by blue, green, or red micro-focused beam at targeted locations. No micro-focal cone ERG response was observed with red light stimulation (since mice and pigs lack red sensitive-cones). Using low intensity stimulation, μfERG measurements from rod photoreceptors could be detected and isolated from cone response.
Conclusions :
Our results show that OCT guided μfERG allows functional evaluation of retinal degeneration. Micro-focal ERG is able to not only characterize differences in rod and cone function but also distinguish different cones with selected stimulation wavelengths. Control of light adaptation and stimulation parameters in the OCT guided μfERG such as intensity, wavelength, and pulsing allow distinguishing differences in functioning of different photoreceptors and cell types.
This is a 2021 ARVO Annual Meeting abstract.