Does field-expanding-strabismus in hemianopia improve mobility?

Abstract

Purpose : Strabismus is hypothesized to compensate for congenital homonymous hemianopia by expanding the visual field if the strabismic eye points into the blind hemifield. With normal retinal correspondence this causes confusion and diplopia, however, with anomalous binocular correspondence (ABC) the patient may have panoramic vision expansion into the blind side. Panoramic vision with ABC is hypothesized to improve mobility, but no studies of mobility for such patients have been published. This prospective study measured vision and mobility-relevant tasks for a subset of hemianopic patients from Children’s Hospital.

Methods : Six hemianopic patients (ages 15 y.o. to 24; hemianopia onset perinatal to 17) performed a pedestrian detection task while driving in a simulator and “walking” in a virtual environment. Pedestrians appeared on the blind or seeing sides and patients responded as soon as they detected the pedestrians. Dichoptic visual fields were measured and standard clinical vision measures were conducted to measure strabismus and ABC.

Results : Two patients had strabismic visual field expansion with ABC while the other four did not. Those with field-expansion detected mobility relevant stimuli presented to their blind hemifields more often (94/130 pedestrian appearances), than those without field expansion (155/264 pedestrians), X²=6.92, p<0.01.

Conclusions : This is the first evidence that strabismic field expansion can compensate for hemianopia in mobility-relevant tasks.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.