Analysis of Visual Recovery After Optic Nerve Crush in Adult Zebrafish.

Zebrafish can successfully regenerate axons after optic nerve crush (ONC). Here, we describe two different behavioral tests to map visual recovery: the dorsal light reflex (DLR) test and the optokinetic response (OKR) test. The DLR is based on the tendency of fish to orient their back to a light source, and it can be tested by rotating a flashlight around the dorsolateral axis of the animal or by measuring the angle between the left/right body axis and the horizon. The OKR, in contrast, consists of reflexive eye movements triggered by motion in the visual field of the subject and is measured by placing the fish in a drum on which rotating black-and-white stripes are projected.