The effects of visual acuity on target discrimination and shooting performance.

PURPOSE

To explore the effects of visual acuity on target discrimination and marksmanship.

METHODS

A randomized, single-blind, repeated measures study was conducted to evaluate the effect of visual acuity on target discrimination and marksmanship. Subjects were examined for inclusion criteria and equivalent plus lens over-refractions necessary to obtain the five test visual acuity ranges. Qualified subjects fired at randomized target presentations from 50 to 300 m while wearing customized spectacles to yield the visual acuity levels being evaluated. Subjects then rotated foxholes for target discrimination sequences. Randomized targets marked as friend or enemy were presented in like manner for each of the five visual acuity levels.

RESULTS

Subjects at acuities better than 0.2 LogMAR were significantly more likely to hit the target than those with acuities equal to or worse than 0.7 LogMAR. Target discrimination results show subjects with acuities between -0.2 and 0.6 LogMAR were significantly more likely to correctly identify the target than those with acuities equal to or worse than 0.7 LogMAR. In addition, those at acuities of 0.0 LogMAR or better performed significantly better than those with acuities between 0.3 and 0.6 LogMAR.

CONCLUSIONS

Visual acuity significantly affects target discrimination and marksmanship performance. Results of this study closely mirror expected findings based on visual angles with acuities in the range 0.3 to 0.4 LogMAR (20/40-20/50) being the transition zone where performance begins to deteriorate. This performance-based evidence fully supports a vision classification system that mandates eyewear to maximize visual performance for deployable military members. Based on the results of this study, the current U.S. Army, U.S. Navy, and U.S. Marine Corps vision readiness standards of 20/40 or better uncorrected or corrected vision seems to be a valid choice because it is the transition point for performance in both target discrimination and marksmanship ability.