Losing your vision, temporarily or permanently, is a rare complication of open heart surgery. This condition is called cortical blindness, which indicates that the problem is in the brain, not the eyes.
I discussed your question with Gulshan K. Sethi, M.D., professor of surgery and medical director of the Circulatory Sciences Program at the Arizona Health Sciences Center and a graduate fellow of the Arizona Center for Integrative Medicine. Dr. Sethi told me that the incidence of cortical blindness following open heart surgery isn't known. The condition can also occur following cerebral angiography (a procedure to see how blood flows through the brain), stroke, seizures, eclampsia (a complication of pregnancy) and treatment with certain chemotherapy agents as well as with cyclosporine, an immunosuppressive drug used to prevent rejection of transplanted organs.
With cortical blindness, the eye appears to be normal and responds to light. The problem is in an area of the brain called the occipital visual cortex, which is responsible for processing information coming from the eyes through the optic nerves. The cause is thought to be an injury to blood vessels that supply this important part of the brain.
Dr. Sethi told me that the outlook for patients with cortical blindness depends on the cause, how severe the blindness is (partial or complete) and the length of the initiating event. In some cases, vision returns within days. Some patients recover part, but not all of their vision.
Although not a recognized therapy for this condition, scalp acupuncture has proven useful for other types of brain injuries related to circulation, and might be worth exploring.
I hope that by the time you read this your friend has fully recovered his sight and is doing well.
Andrew Weil, M.D.