Sky was a 10 year old intact female Border Collie. She had had her left eye semi-closed for the last few months and a several weeks history of lethargy. Ophthalmic examination revealed that her left eye was enophthalmic but visual, had upper lid ptosis and protrusion of the third eyelid. Her right eye, however, was blind, mydriatic and unresponsive to light. A lesion close to the optic chiasm was suspected…