Abstract
Abstract: :
Purpose: Brown’s syndrome is a congenital unilateral vertical gaze field deficit present during the critical visual development period. It is assumed that binocular vision develops in all gaze fields with normal visual alignment but not in the impaired gaze field. Our purpose here was to determine long term binocular sensory adaptation in Brown’s syndrome using data obtained from motion symmetry visually evoked potentials (MSVEP ) (Norcia, et al, Anomalous motion VEPs in infants and infantile esotropia. Invest Ophthalmol Vis Sci 1991; 32(2): 436–9.)) and clinical Titmus Stereo Tests. Methods: Three Brown’s Syndrome patients (ages 5–7) were selected where reliable gaze and non–gaze dependent Titmus Tests and MSVEP responses could be obtained with: Documented Brown's Syndrome since birth. No previous surgery or amblyopia. Minimum 5 year follow–up. Results: Abnormal or asymmetric cortical responses were recorded when the unaffected eye fixed in the affected gaze field (elevation/abduction); normal cortical motion symmetry responses were recorded with fixation in all other gaze fields, monocularly or binocularly. All patients showed the same response at the initial and at the late measurement encounter (5 yrs later). Titmus responses showed the same result profile where the affected gaze filed revealed no stereopsis but showed stereopsis in all other fields at both initial and final encounter (two pts with 40’ and one with 60’). Two patients later underwent superior oblique tenotomy and one was not treated surgically. The unoperated patient outgrew Brown’s Syndrome, developing normal adduction/ elevation of both eyes but no stereopsis/symmetry in the previously affected vertical gaze field yet retaining normal stereo/MSVEP in the opposite vertical gaze field. Conclusions: Vertical fixation sensory deficits in Brown’s Syndrome are retained into visual maturity both with surgical treatment and with spontaneous cure, probably because of abnormal visual alignment during the critical visual development period. Binocular vision and stereopsis can be gaze dependent. Normal and abnormal binocular vision, including good stereopsis, can exist in the same visual system.
Keywords: strabismus • binocular vision/stereopsis • eye movements