Page 77 - JSOM Summer 2018

Optimizing Tactical Medical Performance

The Effect of Light Hue on Vision Testing

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J. Preston Van Buren, DO *; Jeffrey Wake, DO ; Jared McLaughlin, DO ;
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Anthony LaPorta, MD ; Robert W. Enzenauer, MD, MPH, MSS, MBA ; Chris Calvano, MD, PhD 6
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ABSTRACT
Background: Red and blue are the historical tactical lighting Introduction
hues of choice to ensure light discipline and to preserve dark
adaptation. As yet, no scientifically ideal hue for use in Spe- The austere combat conditions typifying Special Operations
cial Operations medicine has been identified. We propose red/ medicine (SOFMED) require balance between successful visual
green polychromatic light as a superior choice that preserves task completion and preservation of tactical light discipline to
visual function for tactical medical tasks in austere settings. minimize risk. A survey of SOFMED Operators published in
Methods: Thirty participants were enrolled in this institu- 2013 indicated that casualty outcomes were directly affected,
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tional review board–approved study. Participants completed both positively and negatively, by the lighting system used.
four vision tasks in low-light settings under various lighting Our goal for this study was to identify the optimal lighting
conditions. The Pelli-Robson Near Contrast Sensitivity test hue for performance of SOFMED visual and technical tasks
(PR), tumbling E visual acuity test, Farnsworth D-15 color- while maintaining Operator and casualty concealment across
vision test (FD15), and pseudoisochromatic plate (PiP) testing ground, marine, and aviation settings.
was performed under white, green, or red light illumination
and also red/green and red/green/yellow lights. PR and tum- In this study, we quantify the impact of illumination wave-
bling E tests were performed using blue and blue/red lights. length on visual acuity, contrast sensitivity, and color vision.
Results: The test results for each light were compared against We predicted that red/green polychromatic lights would out-
a white-light standard. Contrast sensitivity as measured by perform other polychromatic lights and monochromatic lights
PR testing showed no statistical difference when white light when compared with a white-light standard.
was used compared with red/green or red/green/yellow light,
and the differences between red, green, blue, and blue/red all Methods
were statistically different from when white light was used.
When measuring visual acuity, blue light was the only color A total of 30 healthy, first- and second-year volunteer medical
for which there was a statistically significant decrease in visual students from Rocky Vista University College of Osteopathic
acuity in comparison with white. There was no reduction in vi- Medicine (RVUCOM) and Kansas City University of Medicine
sual acuity with any other lights compared with white. Perfor- and Biosciences College of Osteopathic Medicine volunteered
mance on FD15 testing with all single-hue and multihue lights to be a part of this study, which took place between May 1
was significantly worse than with white light for measuring and May 14, 2016. RVUCOM’s Human Institutional Review
color-vision perception. Color discrimination as measured by Board approved the study (HIRB approval no. 2014-003).
PiP testing showed red and green light was significantly worse Participants were not color blind and, if needed, used any cor-
than with white light, whereas test results when green/red and rective vision devices such as contacts or glasses so that vision
green/red/yellow lights were used were not statistically differ- was corrected to at least 20/20. Colorblind participants and
ent from white. Conclusion: Red/Green/yellow and red/green participants with corrected or uncorrected vision worse than
were superior light sources and performance results only were 20/20 were excluded.
worse than white light on FD15 testing.
Each subject completed four vision tasks in low-light indoor
settings under different lighting conditions. All lights were
Keywords: SOFMED; tactical lighting; visual acuity; contrast Tomahawk tactical lights (First-Light USA, https://www.first
sensitivity; color vision
light-usa.com; Figure 1). The white, monochromatic red, mono-
chromatic blue, monochromatic green, duochromatic blue/red,
*Correspondence to 3001 South Downing St, Englewood, CO 80113; or jeffrey.vanburen@rvu.edu.
1 ENS Van Buren was a medical student of the class of 2018 at Rocky Vista University College of Osteopathic Medicine (RVUCOM). He is
currently enrolled in the Navy Health Professional Scholarship Program. 2LT Wake was a medical student of the class of 2018 at RVUCOM.
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He is currently enrolled in the Army Health Professional Scholarship Program. He has maintained his status as a Certified Athletic Trainer and
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has worked in many capacities as an athletic trainer prior to medical school. 2LT McLaughlin was a medical student of the class of 2018 at
RVUCOM. He is currently enrolled in the Air Force Health Professional Scholarship Program. COL (Ret) LaPorta retired from the US Army as
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a Colonel after over 26 years of service. He has served in every aspect of medical education and is currently the professor of Surgery and director
of Rocky Vista University’s Military Medicine Honors Program. BG (Ret) Enzenauer is a retired M-day Guardsman who served most recently
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as the assistant adjutant general for space and missile defense, Colorado Army National Guard, 2010–2015. In the civilian sector, Dr Enzenauer
is professor of ophthalmology and pediatrics and chief of ophthalmology at the Children’s Hospital of Colorado in Aurora. D. Enzenauer has
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over four decades of uniformed service on active duty and in the Army National Guard. MAJ Calvano is an oculoplastic surgeon and currently
serves as the US Army Reserve Ophthalmology Consultant to the Surgeon General. A Fellow of the American College of Surgeons and also the
American Society of Ophthalmic Plastic and Reconstructive Surgery, Dr Calvano has been deployed as a flight surgeon with combat aviation to
Afghanistan, Kuwait, and Iraq. He recently was in an Active Duty Operational Support position as medical liaison officer in the US Army Special
Operations Command G9 Science and Technology division.
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