Abstract
Purpose: :
To probe the retinal optophysilogical and electrophysiological response to visual stimuli in a rat retina model by use of a combined, high speed, ultrahigh resolution optical coherence tomography (UHROCT) and full filed electroretinography (ERG) system.
Methods: :
A combined UHROCT+ERG system, recently developed by our research group, was used to measure in-vivo and simultaneously the optical and electrical response of the rat retina to optical stimuli of different color, duration and intensity. The UHROCT system operates in the 1060nm wavelength region, outside the spectral range of the ERG visual stimuli, and provides 3µm axial and ~5µm lateral resolution in the rat retina at a data acquisition rate of 47 kHz. The UHROCT system was combined with a commercial full field ERG system (Diagnosys LLC) for simultaneous acquisition of the optophysiological and electrophysiological signals. UHROCT + ERG data was acquired from healthy rat retinas of female Long Evans rats using visual stimuli of various duration, luminance level and spectral characteristics.
Results: :
UHROCT cross-sectional and volumetric tomograms acquired from healthy rat eyes showed clear visualization of all intra-retinal layers, the choroid and the sclera and were associated with normal ERG traces. Preliminary results showed increase of the optical scattering (positive optophysiological signal) in the photoreceptor outer segment layer during and immediately after 250ms long, green (532nm) light flashes, while a corresponding decrease in the optical scattering (negative optophysiological signal) was observed in the photoreceptor inner segment layer of the retina.
Conclusions: :
We were able to detect in-vivo in an animal model, changes in the optical properties of the rodent retina (photoreceptor layer) resulting from exposure to visual stimuli. The combined UHROCT (morphology and optophysiology) + ERG system could provide ophthalmologists with the means for deeper understanding of the processes occurring in the retina in health and disease.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • electroretinography: non-clinical • retina