# Superior monocular visual function but compromised binocular balance in precision shooters compared to age and refraction matched controls

## TL;DR

Precision shooters have better monocular vision but worse binocular balance compared to non-athletes, suggesting visual adaptations from training.

## Contribution

The study reveals task-specific visual adaptations in precision shooters, including enhanced monocular acuity and suppressed binocular balance.

## Key findings

- Shooters showed superior near visual acuity and contrast sensitivity compared to controls.
- National-level shooters had more stable fixation and better stereoacuity.
- Frequent monocular use in shooting correlates with reduced binocular balance and convergence issues.

## Abstract

Shooting sports demand exceptional visual performance, yet detailed assessments of visual function in precision shooters remain limited. This cross-sectional study evaluated 28 pistol and rifle shooters and 20 age- and refractive-error-matched non-athletic controls. Participants underwent comprehensive visual assessments, including tests of visual acuity (VA), Vernier acuity, contrast sensitivity, binocular vision, accommodation, ocular biometry, perimetry, and eye movement tracking. A subgroup of national-level athletes was also analyzed. Compared to controls, shooters demonstrated superior near VA (−0.08 ± 0.06 vs. 0.03 ± 0.07 logMAR; p = 0.003), binocular Vernier acuity (5.4 ± 3.2 vs. 8.7 ± 5.1 arcsec; p = 0.032), and dominant eye contrast sensitivity (p = 0.005). National-level shooters showed fewer gaze shifts (p = 0.044), more stable fixation, and better stereoacuity (25 vs. 35 arcsec; p = 0.005). Modality-specific differences were observed: pistol shooters exhibited better distance acuity and central field sensitivity, while rifle shooters—despite being older—performed better in near VA. However, covering one eye to avoid diplopia, which is inherent in precision shooting, may cause suppression of the covered eye when performed frequently and for prolonged periods. This ultimately may explain why shooting experience correlates with reduced binocular balance and a worse near point of convergence (r = 0.335, p = 0.020). These findings suggest that visual expertise in precision shooting is linked to task-specific visual adaptations. Tailored visual training programs may enhance performance and mitigate training-induced imbalances.