Extraordinary Dynamic Near Vision in Champion Shotgun Shooters: PDI Check Evaluation of Stereo and Color without Floor Effect

Abstract

Background: Conventional near and stereo tests have a "floor effect;" inability to discriminate normal from super-normal. Shotgun champions require unique performance in binocularity and rapid color discrimination.

Patients and methods: Twenty-nine champion clay-target shooters, 14 normal Army and 12 color-normal subjects were tested with conventional near vision tests and on PDI-Check, a series of dynamic, near vision tests on the autostereoscopic Nintendo console.

Results: Conventional tested shotgunners had all perfect Ishihara and 75% best 40 sec Stereo fly while Army had 92%perfect Ishihara and 69% best stereo fly. On PDI-Check, experienced shotgunners with median stereo of 17 (IQR 12-41) arc sec were better than Army volunteers 59 (IQR 30 to 487) arc seconds (Mann-Whitney U=62, p=0.04). Median PDI-Check for shotgun compared to Army was 88% compared to 84% for blue cone, 90% compared to 84% for green and 77% compared to 72% (red, Mann-Whitney p=0.05). Adding dark cherry filter shooting glasses improved the red and green color detection (p<0.01). This study lacked power to detect eye dominance using PDI Check color or stereo.

Conclusion: Many champion shotgun shooters had outstanding dynamic near stereo and better-than-average color vision which could be optimized with dark filter spectacles for red and green hues. PDI Check not only helps identify abnormal binocularity and color vision, but it can clarify supranormal vision as well.

Keywords: color vision; eye dominance; stereopsis.

Conflict of interest statement

Drs Arnold and Smith are board members of PDI Check which makes vision screening games for autostereoscopic screens like the Nintendo 3DS. Dr. Arnold has a patent pending on PDI Check. Dr. Arnold is President and board member of Glacier Medical Software which markets ROP Check cloud-based NICU software. Dr. Arnold coordinates the Alaska Blind Child Discovery which has received discounted vision screening technology from several vendors. Dr. Arnold is the investigator and protocol developer for PEDIG. He also serves as the non-paid advisory board for PlusoptiX, Adaptica, and GoCheck Kids. Mr. Rue is an NSCA Level III Instructor. Stephen Brown is attending Martin Methodist University on a shotgun scholarship. The authors have no other conflicts of interest to report.

© 2021 Brown et al.

Figures

Figure 1

Box and whisker plots of near vision performance from PDI Check comparing champion shotgun shooters with normal Army volunteers. The vertical scale covers three variables; visual acuity as the 20/20 denominator calibrated near output from PDI Check, arc seconds of stereo (Titmus Fly and PDI Check) and percent color scores. Va-right and Va-left are monocular rivalry Landholt C forced-choice dynamic recognition scores. Trichromatic dynamic monocular scores separate red cone, green cone and blue cone performance. Subjects included experienced shotgun shooters (orange whisker plots), age-matched Army volunteers (green boxes with black whiskers) and age-matched Innova-Rabin passed normal volunteers (purple box with black whiskers). Shotgun shooters tested colors with and without dark and filtered goggles. Statistically different groups identified by red double arrows below.