Electroretinogram and Fundus Imaging in Mice

Full-field electroretinograms (ERGs) were recorded as described previously [26 (link)]. Briefly, mice were dark-adapted overnight and were anesthetized using 85 mg/kg ketamine and 14 mg/kg xylazine (Henry Schein Animal Health, Dublin, OH, USA). Eyes were dilated with 1% cyclopentolate and covered in Gonak (Akorn Pharmaceuticals, Lake Forest, IL, USA). Platinum wire loops were placed in contact with the cornea through a layer of Gonak. Using the UTAS system (LKC, Gaithersburg, MD, USA) full-field scotopic ERG responses were recorded from each eye in response to a single 157-cd s/m² flash. Fundus imaging was performed using the Micron IV system (Phoenix Research Laboratories, Pleasanton, CA, USA). Animals were anaesthetized/dilated as for ERG but were not dark-adapted. Brightfield images were captured first, and then HA-NS distribution was analyzed by imaging with the green filters (451.5–486.5 nm excitation and 488 nm emission, for fluorescein) or red filters (553 nm excitation and 627 nm emission). All images were captured using StreamPix^® software (Phoenix Research Laboratories, Pleasanton, CA, USA). For OCT, animals were anesthetized and eyes dilated as for fundus imaging. OCT images were captured using an Image Guided OCT2 (Phoenix Research Laboratories). Images were captured at 100 fpm using the Reveal OCT software.