Optic nerve regeneration in goldfish under light deprivation.

Regeneration following bilateral optic nerve crush was studied in groups of goldfish housed either on a standard diurnal cycle or under total light deprivation. Unoperated fish were included in each deprivation condition. Regeneration was only slightly delayed in the surgical group housed under light deprivation (68-81 days), compared to fish undergoing regeneration on the diurnal cycle (59-63 days). Visual capacity, as judged by days to meet criterion on a visual pattern discrimination task, was unrelated to deprivation condition, but significantly lessened in fish having regenerated optic nerves. These results are discussed in terms of visual acuity following optic nerve regeneration and mechanisms of axonal reconnection.