Experimental cryosurgical lesion of the optic nerve.

The right optic nerves of three cynomolgus monkeys were frozen under direct visualization after a modified Kröhnlein operation. Left optic nerves were subjected to an identical procedure without freezing. Postoperatively, visual evoked responses (VERs) could not be obtained by stimulating right eyes, while electroretinograms from both eyes and VERs obtained by stimulating left eyes were normal. Extensive lesions which were found in the right optic nerves of all animals were histologically similar to those obtained by freezing in the brain.