Introduction: The standard issue clear or sun Military Combat Eye Protection (MCEP) is often inadequate in visually challenging training or combat environment. Intermediate-tinted lenses may offer a viable option for warfighters operating in dynamic visual conditions such as moving rapidly from bright sunny areas to darker building interiors in combat. Because the use of intermediate-tinted lenses has been delayed as a result of a potential negative impact on vision performance such as color perception, this investigation evaluated several commercially available intermediate-tinted lenses for operation performance during a U.S. military field training. Test lenses complied with all the requirements of the current MCEP except for the visible light transmittance (VLT) values that ranged between 32 and 62%. Materials and Methods: Study subjects consisted of 22 service members who attended a military Close Combat and Marksmanship training course in May 2019. Visual and pistol marksmanship performance of three intermediate-tinted lenses (Eye Safety Systems [ESS] Copper [32% VLT], Oakley Prizm TR45 [44% VLT], and ESS Bronze [62% VLT]) was compared to that of a standard issue MCEP, ESS Clear (90% VLT). Quick contrast sensitivity function test was used to assess quality vision (AULCSF, area under a log contrast sensitivity function) and visual acuity (CSF Acuity). Color vision was assessed by Cone Contrast Test. Pistol marksmanship (Bill Drill) was used for performance testing. A pre-survey inquired about MCEP use, and a MCEP survey during the pistol marksmanship testing inquired about lens performance and ranking. Results: AULCSF and CSF Acuity were significantly affected by the lenses (general linear model, repeated measures, P . 05). Subjectively, there were no statistically significant differences among study lenses in perceived "clarity of vision,""ability to clearly identify the target,"or "overall performance"(Friedman test and Wilcoxon signed-rank post hoc test with Bonferroni adjustment, P >. 017). Participants ranked Prizm TR45 (44% VLT) and ESS Bronze (62% VLT) lenses significantly more favorably than EES Clear (P =. 001 and P =. 009). Conclusions: Quality of vision and visual acuity decreased with darker lenses; however, the study lenses had insignificant impacts on pistol marksmanship and subjective acceptance. Our surveys indicated that Intermediate-tinted lenses were operationally acceptable and preferred over a standard issue MCEP. While more evaluations for color vision deficient subjects are needed, overall results suggest that commercially available intermediate-tinted lenses may be a viable option to enhance protection and performance in a visually dynamic combat environment.
CITATION STYLE
Gao, H., Clasing, J. E., Kang, R. N., & Kinney, M. J. (2021). Effects of Intermediate-Tinted Lenses on Pistol Marksmanship and Visual Performance. Military Medicine, 186(11–12), E1215–E1220. https://doi.org/10.1093/milmed/usaa517
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