Measuring Visual Acuity in Mice

Visual acuity threshold was measured daily by OKT response using Optometry software and apparatus (Cerebral Mechanics Inc., Alberta, Canada) as previously described (35 (link)–37 (link)). Briefly, mice are placed on a pedestal inside a box with a virtual cylinder consisting of vertical lines projected on four computer screens of the box surrounding the animal. The vertical lines rotate at varying frequencies, and tracking behavior is assessed in a stepwise manner as the thickness of the lines are reduced. Visual acuity is represented as the highest spatial frequency at which mice track the rotating cylinder. Optokinetic tracking is a temporal-to-nasal reflex, and therefore counter-clockwise and clockwise rotations exclusively test the right and left eye, respectively. When EAE-induced motor deficits rendered mice without the balance and stability to adequately perform OKT testing, a measurement was not recorded for the affected mouse on that day.