Superior oblique overaction in patients with true Brown's syndrome.

The charts of all patients with the diagnosis of congenital Brown's syndrome seen between July 1983 and June 1984 were examined retrospectively. In the past, overaction of the ipsilateral superior oblique (OAISO) was felt by most authors to be absent or minimal. Our study revealed that separate observers consistently documented the presence of an OAISO in about one-fifth of the selected patients. The presence of OAISO has not been emphasized previously and still remains controversial. We felt that an extremely tight superior oblique might cause an OAISO. We therefore statistically compared its presence to the presence of a downshoot. The presence of an OAISO to abnormal head tilt, abnormal chin position, amblyopia, and abnormal stereo was also compared statistically. Finally, we emphasize a technique of forced ductions that differentiates Brown's syndrome from an inferior oblique palsy, but which also alerts the examiner to the presence of an inferior rectus restriction or other posteriorly located restrictions.