Strabismus and binocular diplopia due to advanced glaucomatous visual field loss

Purpose To describe a small series of patients with glaucoma whose strabismus and binocular diplopia were due to advanced visual field loss and inability to maintain sensory and motor fusion. Methods This study is an observational case series of 3 patients with binocular diplopia, associated with variable strabismus, which was due to advanced visual field loss. Results Specific characteristics of the strabismus associated with advanced glaucomatous visual field loss were a subjective floating second image and marked variability of the prism and alternate cover measurements. Measured hypertropia changed in magnitude over a few seconds or a few minutes (even in 1 patient to a hypotropia), which distinguishes this specific type of strabismus from other types of comitant or incomitant strabismus associated with glaucoma. Although visual acuity was 20/400 or better in both eyes in all patients, there was advanced visual field loss in at least one eye. All patients responded poorly to prism, but their symptoms improved with a Bangerter filter applied to the spectacle lens or a MIN occlusion lens to further blur the worse-seeing eye. Conclusions Variable strabismus associated with advanced glaucomatous visual field loss appears to be a distinct clinical entity that should be distinguished from other types of strabismus associated with glaucoma. Management of this specific type of strabismus is limited by inadequate visual field to fuse, analogous to hemifield slide, and therefore prism and/or strabismus surgery is unlikely to be successful. Primary treatment options include optical blur with Bangerter filters or a MIN occlusion lens although some patients prefer to ignore the second image.