Individuals with esotropia may have a reduced horizontal binocular visual field (VF) that may impair driving ability, according to a study published in Eye. These findings suggest that individuals with esotropia undergo a VF test prior to receiving a driver’s license.
Researchers included a total of 49 participants consisting of individuals with orthotropia (n=10; mean age, 41.90 years), exotropia (n=20; mean age, 40.89 years), and esotropia (n=19, mean age 43.25 years) in the analysis. Participants underwent prism cover tests and monocular and binocular VF assessment.
No significant differences in binocular best-corrected visual acuity (BCVA) were noted between the groups or in the BCVA of amblyopic eyes between patients with esotropia and exotropia (P =.99). The BCVA of patients with a tropia, however, was significantly reduced compared with patients with orthotropia (P <.01 for both tropias).
Binocular VF was significantly more limited among patients with esotropia (122.8°) compared with individuals with orthotropia (141°) or exotropia (138.3°). A total of 6 (31.6%) participants with esotropia had a binocular VF that failed to meet UK driving standards for licensure.
The horizontal VF extent of the eyes with amblyopia was significantly reduced among patients with esotropia (98.70°) and exotropia (104.75°) compared with individuals with orthotropia (121.00°; P =.004 and P =.045, respectively).
The researchers stress that individuals with strabismus who meet visual acuity standards for driving may be limited by VF defects. “We found that the horizontal extent of [binocular VF] is significantly smaller and more variable in adults with congenital esotropia,” according to the researchers. “Adults with esotropia applying for a driving license may fall below visual field standard in the UK and in Europe.”
A failure to assess VF repeatability is an acknowledged limitation to the research.
Alfaqawi F, Young J, Kaye SB. Binocular visual field in adults with horizontal strabismus and driving requirements. Eye. Published online December 2, 2022. doi:10.1038/s41433-022-02319-5