Acquired unilateral visual loss attributed to an accommodative spasm

Background. Accommodative spasm (AS) has been reported to be a rare cause o f an acquired unilateral visual loss. We describe a unique case of acquired visual loss due to an apparent unilateral AS triggered by occlusion of the contralateral eye. Clinical examination and photorefraction techniques wer e performed during the acute phase of the disorder and in the follow-up eva luations. Case Report. An otherwise healthy 27-year-old woman presented wit h a 2-month decrease of vision in her left eye. Unaided visual acuity in th e right eye was 20/20 and in the left eye was finger counting. Orthophoria existed at distance and near. The decrease in vision in the left eye was at tributed to an apparent unilateral AS of 5 D, which occurred only when the right eye was occluded. Under the occluder, the right eye also manifested a n AS. With the left eye occluded or with binocular viewing, the right eye a nd left eye accommodated normally. With a 5 D convex lens before the right eye, the visual acuity in the left eye was 20/20. Refractive error with cyc loplegia revealed low hyperopia in each eye. Conclusion. AS can be the caus e of acquired unilateral visual loss. To our knowledge, this is the first d ocumented report of an apparent unilateral AS triggered by occlusion of the contralateral eye.