My husband is a photographer. When he photographs a group, he tends to stand two to five feet to the right of center, yet he swears that he is standing directly in front of the center person. Today, we had to refund money on an important job because someone was cut off in the left side of the picture. There was plenty of space on the right. I have mentioned this to our optometrist before my husband's eye exams, but he doesn't have a clue about what could be wrong. New glasses have not helped. Any ideas?

M.D.

Visual information from the eye travels to the visual cortex of the brain. It is the visual cortex of the brain that interprets all of the images that we see. Damage to the pathway that runs from the eye to the visual cortex will cause a visual-field defect. A common visual-field defect is the loss of vision to one side. Interestingly, people with visual-field defects may not realize they have a problem.

To test for a visual-field defect, the doctor will have the patient stare directly ahead and then flash fingers to each side. If the patient can not see the fingers, then a visual-field defect is present. Ophthalmologists also have a special machine that very accurately maps out any visual-field defect.

I discussed your case with a neurologist who takes care of a lot of patients with visual-field defects. His first thought was to inquire whether you ever found your husband driving close to or crossing over the center line. Even if that is not happening, it is important that your husband have a complete eye and neurologic exam. There are many causes of visual-field defects, including optic nerve damage, pituitary tumors, brain inflammation, brain lesions or strokes. Only a complete work-up will be able to determine the presence and source of a visual-field defect.