Bilateral idiopathic Brown's syndrome with delayed onset in the second eye

We describe 6 cases of a previously unreported variation of bilateral Brown's syndrome that presented in congenital form in one eye and developed later in the fellow eye with no underlying cause.

We reviewed the clinical records of 6 patients from 6 separate practices to determine whether there were any common clinical features on presentation or in their clinical courses.

All 6 patients were diagnosed with unilateral congenital Brown's syndrome at the first ophthalmologic assessment but showed no evidence of the syndrome in the fellow eye. In 5 cases the contralateral syndrome developed in the second eye after surgery was performed on the first eye, and in 1 case it developed before any surgery was done. The ages at onset of the syndrome in the second eye ranged from 2 to 8 years. None of the children had any evidence of systemic illness or local orbital disease to explain an acquired Brown's syndrome.

To our knowledge, this is the first reported series of cases of bilateral Brown's syndrome that manifested sequentially in the eyes with no known causes for an acquired syndrome in the second eye. This finding supports the premise that congenital and acquired Brown's syndrome are on a continuum with a common pathophysiology of restriction of free movement of the superior oblique tendon in the trochlea.