By: ELAINE ZABLOCKI APR. 1, 2006

LOS ANGELES — Vertical heterophoria is a newly recognized syndrome responsible for a high proportion of otherwise undiagnosable cases of dizziness and headaches, Dr. Arthur J. Rosner said at the annual meeting of the American Academy of Otolaryngology-Head and Neck Surgery Foundation.

In vertical heterophoria, one eye sees an image higher than the other eye does. This may be caused by the relative position of the eyes or to neurologic or muscular anomalies. The brain is intolerant of the unclear image and responds with compensatory mechanisms. The resulting strain can lead to symptoms that mimic sinusitis, inner ear disorders, and migraine headaches.

“When patients present with dizziness, I check for possible causes such as benign paroxysmal positional vertigo, sinusitis, and tumors,” Dr. Rosner said in an interview. “When I rule out the more common diagnoses and I’m left with unexplained dizziness, 90% of the time it turns out to be due to vertical heterophoria.”

Dr. Rosner, an otolaryngologist in private practice in Sterling Heights, Mich., uses a Quality of Vision questionnaire to evaluate patients, asking whether they experience double vision, blurred vision, poor depth perception, and other visual problems. Those who score high on the questionnaire are referred to an optometrist.

In his study, 100 patients were sent for optometry evaluation, and 29 of these had vertical heterophoria. They were treated with new glasses using fractional units of vertical and horizontal prism. After treatment, symptoms were evaluated using the Quality of Vision questionnaire, which showed a mean symptom reduction of 50%.

So far, Dr. Rosner has treated more than 500 patients with vertical heterophoria, most of them successfully. The symptoms that were most improved included dizziness on bending down and standing up, blinking to clear vision of distant objects, unsteadiness when walking, fatigue when reading, and poor depth perception.

To identify this often unrecognized condition, physicians should question patients more vigilantly about visual stimulation that leads to dizziness, Dr. Rosner said. “Someone may be seeing double, having problems reading, or bumping into things, but they don’t volunteer this information because they think it’s normal. They’ve lived with it for years.” Additional research is needed to determine the causes of and treatments for the disorder, he added.