Abstract
Purpose :
To present the status of in vivo visualization and quantification of Retinal Ganglion Cells (RGCs) in mice using analysis of serially acquired Optical Coherence Tomography volumes.
Methods :
We used our custom mouse retinal Scanning Laser Ophthalmoscopy / Optical Coherence Tomography (SLO/OCT) system to acquire serial OCT volumes (with corresponding SLO intensity and fluorescence data) to provide input for temporal analysis of serially acquired Optical Coherence Tomography volumes. The processing of serially acquired OCT volumes allows the reduction of the speckle contrast and enhancement of the cellular retinal morphology using static and dynamic OCT signal components. Novel visualization methods subtracting retinal vasculature have been tested as well. To showcase the performance of this technique, a mouse line with fluorescently labeled RGC based on RGCs transcription factor (Isl2-GFP) has been used in this study.
Results :
Temporal analysis of serially acquired OCT volumes enhanced the image quality of RNFL and enabled RGCs visualization. However, the results were highly dependent on the optical quality of the measured mice optics and retinal stability during acquisition. The effect of the number of processed volumes and duration of the measurement will be discussed. Use of mice with fluorescently labeled RGCs allows validation of RGCs position using fluorescent SLO system, providing a direct comparison with RGC soma’s visualized by non-invasive OCT.
Conclusions :
In these studies, we used a novel temporal analysis of serially acquired OCT volumes to allow visualization of RGC in mice in vivo. There was no need for Adaptive Optics to achieve that in some mice that were imaged. However, our results suggest that better control of ocular aberrations would greatly enhance the OCT signal and potentially reduce the number of volumes needed for successful visualization of RGC’s somas. The ability to visualize and follow RGCs in vivo using a non-invasive imaging method should allow a reduction in the number of animals needed in future studies. These methods are needed for efficient in vivo monitoring of cellular morphology in animal models of Glaucoma during disease progression and therapeutic innervation.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.