In vivo Adaptive Optics Imaging of Rat Retinal Ganglion Cells

Abstract

Purpose:: Rodent models of retinal degenerations have proven useful in enhancing our understanding of the disease progression in humans. We have developed a fluorescence adaptive optics scanning laser ophthalmoscope (FAOSLO) suitable for imaging the rodent retina in vivo. The ability to resolve single cells noninvasively in the living retina will allow more detailed study of normal eyes and transgenic and knockout models of retinal disease, and for assessing the efficacy of retinal disease therapies.

Methods:: Intravitreal injections of adeno-associated viral vectors were used to express enhanced green fluorescent protein in ganglion cells of Sprague-Dawley rats. Rats were anesthetized and a contact lens was placed on the eye during high-resolution imaging. A FAOSLO was used to acquire simultaneous reflectance and fluorescence images in vivo over a 3-degree field with an 830-nm laser diode and a 488-nm excitation wavelength from an argon/krypton laser, respectively. Adaptive optics correction of the rat eye’s aberrations was performed in reflectance at 904 nm.

Results:: Ganglion cell bodies and axons were clearly resolved in registered images taken from living eyes. Adaptive optics (AO) correction increased resolution and contrast in FAOSLO images from the rat retina, enabling the visualization of cellular structures that were not seen prior to AO correction. Typical total rms wavefront errors after AO correction were ~0.1 µm over a 2.65-mm pupil.

Conclusions:: In vivo imaging of rodent ganglion cells may be useful in a number of future applications. The large numerical aperture of the rat eye coupled with adaptive optics fluorescence imaging offers the opportunity for imaging naturally reflective and fluorescently-labeled cells and their associated processes in normal and diseased rodent eyes.

Keywords: ganglion cells • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retina