High prevalence of strabismic visual field expansion in pediatric homonymous hemianopia

Abstract

If homonymous hemianopia develops in childhood it is frequently accompanied by strabismus. In some of these cases the strabismus increases the size of the binocular visual field. We determined how prevalent visual-field-expanding strabismus is in children who have homonymous hemianopia. Medical records were examined from 103 hemianopic patients with exotropia (XT) or esotropia (ET). For each participant, we determined whether their strabismus was in a direction that resulted in visual field expansion (i.e. left exotropia with left homonymous hemianopia). Ages at which hemianopia and strabismus were first noted were compared to determine which developed first. The prevalence of XT (24%) and ET (9%) with homonymous hemianopia were both much higher than in the general population (1.5% and 5%, respectively). More strabismic eyes pointed to the blind than seeing side (62 vs 41, 60% vs. 40%, p = 0.02). Exotropic eyes were five times more likely to point to the blind side than esotropic eyes (85% vs 15%). Strabismus, especially exotropia, is much more common in pediatric homonymous hemianopia than in the general population. The strabismus is significantly more often in a visual field-expanding direction. These results support an adaptive role for the strabismus. Patients with HH and exotropia or esotropia should be aware that their visual field could be reduced by strabismus surgery.

Review: Binocular double vision in the presence of visual field loss

“…The possibility that strabismus providing field expansion in HH is adaptive has been raised in the literature, but remained unresolved ( Bronstad et al., 2018 ; Donahue & Haun, 2007 ; Economides & Horton, 2021 ; Herzau et al., 1988 ; Koenraads et al., 2014 ). The more recent data on the higher prevalence of field expanding configurations in comparison with non-expanding conditions ( Bronstad et al., 2018 ) seems to support the idea that these strabismus configurations are adaptive in a pediatric population.…”

“…The possibility that strabismus providing field expansion in HH is adaptive has been raised in the literature, but remained unresolved ( Bronstad et al., 2018 ; Donahue & Haun, 2007 ; Economides & Horton, 2021 ; Herzau et al., 1988 ; Koenraads et al., 2014 ). The more recent data on the higher prevalence of field expanding configurations in comparison with non-expanding conditions ( Bronstad et al., 2018 ) seems to support the idea that these strabismus configurations are adaptive in a pediatric population. By further reviewing the high prevalence of field expanding strabismus in tunnel vision conditions, such as RP, or advanced glaucoma, we have added further support to the notion that field expansion strabismus may be an adaptive response to field loss.…”

“…Similar ratio of exotropia/esotropia (19/75) was also found in study of 100 strabismics ( Pratt-Johnson & MacDonald, 1976 ). In pediatric population with HH, both exotropia and esotropia occur substantially more often, 23.6% and 8.8%, respectively ( Bronstad, Peli, Liu, Doherty, & Fulton, 2018 ). Note that the ratio of exotropia/esotropia (23.6/8.8) is reversed with HH, many more with exotropia than esotropia.…”

“…In the retrospective review of charts at Boston Children's Hospital, we identified 103 patient records with both HH and strabismus ( Bronstad et al., 2018 ). Of the 75 with exotropia, 53 (70%) had an ipsilateral exotropia that potentially expanded the field ( Figures 6 C and 6 D), whereas from the 28 with esotropia only nine (32%) had the field expanding deviation ( Figures 6 E and 6 F).…”