Regenerating Field Cut after Surgery?

My son had a hemispherectomy last September to control his seizures at the age of 4 and a half.  We were told that he would lose right side peripheral vision in both eyes and he has.  He runs into things rather frequently if they are to the right.  He is getting better at turning his head to see things all around him.  My question is could this regenerate?  Or a percent of it regenerate? The surgeon says absolutely not, but our neurologist seems to think that it could.  Any ideas?  Thanks.

[John C Hagan III, MD, FACS, FAAO]

Your question is answered below by 'circumspect' a physician member of the American Academy of Ophthalmology. Sorry for the delay in answering your question.

[circumspect]

I am a board certified ophthalmologist but not the forum physician. Nerves in the brain and spinal cord are central nerves and generally do not regenerate. Peripheral nerves often will regenerate when cut. That's why if a hand is cut off surgeons will attempt to sew the nerves back together, but if the spinal cord is cut they do not attempt to sew it back together.

The optic nerve and the nerve bundles that visual nerves follow in the brain (optic tract and optic radiations) are central nerves and generally do not regenerate. The most common lesions that cause loss of peripheral vision in both eyes are strokes and tumors. The optic nerves cross at the base of the brain (optic chiasm) and fibers fron each eye cross to the other side. Lesions behind the optic chiasm cause loss of the peripheral vision on the side opposite the lesion. (ie a stroke on the back right brain will cause a left hemi-anopsia or visual field loss.

My experience is identical with traditional teaching about brain caused peripheral vision loss. It is permanent, it sometimes gets smaller over the 6 months following the stroke or tumor removal but after 6 months improvement almost never happens. Patients adjust to the field loss and function better with time so after 6 months it's not as much of a problem for the patient as right after the stroke.

There is a new technique for trying to improve visual field loss after a stroke. The program is called Vision Restoration Therapy (VRT) and uses instruments and techniques marketed by NovaVision. It is expensive and time consuming and not widely available. It is very controversial and most ophthalmologists would consider its benefits unproven and its use experimental. I am skeptical of its claimed benefits.

Things that doctors can't explain do occur and in my 30 years in ophthalmology I have had one patient, a doctor's mother, in her 70's that had a stroke and a total hemianopsia on the left that cleared completely over 4 months. It shouldn't have happened but it did. We can always hope and pray for the unexplained cure or improvement.

Best of luck to you and your child.

JCH MD Board Certified Ophthalmologist