Retinal Imaging and Analysis in Mice

Mice were anesthetized (ketamine and xylazine) and pupils were dilated with one to two drops of Tropicamide Ophthalmic Solution 1% (Bausch & Lomb, Tampa, FL, USA). To create a consistent, optically transparent interface, an ocular demulcent solution containing hydroxypropyl methylcellulose ophthalmic (Gonak, Akorn, Lake Forest, IL, USA) was applied to the eye. Ultra-high resolution spectral domain optical coherence tomography (SD-OCT) imaging was performed on both eyes at the end of experiments (Bioptigen SD-OCT system, Research Triangle Park, Durham, NC, USA) as described [21 (link)]. In short, a series of 100 b-scans were collected, stacked, and aligned spatially to form a registered three-dimensional rendering of the retinal volume. By averaging 20 separate b-scans along the same horizontal axis and spatially aligning them, a high-resolution horizontal b-scan centered on the optic nerve head was obtained. The total retinal thickness, measured as the distance (in µm) between the retinal pigment epithelium and the inner limiting membrane, was calculated for each location. The Micron II retinal imaging microscope (Phoenix Research Laboratories, Inc., CA, USA) was used to capture fundus pictures.