Thanks for you question. Unfortunately there are no treatment options available that will restore vision in that eye. Once the retina
is deprived of its blood supply the cells do not regenerate.
The only treatments available are for immediately after the event has occurred (within a few hours) which can occasionally restore vision.
The key thing for your husband is to ensure a similar thing does not happen to his other eye by managing his cardiovascular risk factors. You will need to discuss these with his cardiologist or family doctor to ensure he is on the correct preventative medications e.g. for blood pressure and cholesterol