A Comparative Study of Vestibular Performance in Pilot and Non-Pilot Service Members in Naval Aviation

The vestibular system plays a critical role in maintaining gaze stability during head movement, a function largely controlled by the vestibulo-ocular reflex (VOR). When the VOR is impaired, individuals may experience blurred vision, dizziness, and other symptoms that interfere with daily activities. Dynamic visual acuity (DVA), or the ability to clearly identify a visual target during head movement, provides a functional measure of VOR performance and can be assessed using computerized tools. Military aviators are frequently exposed to situations that place high demands on the vestibular system. This study aims to evaluate DVA among rotary wing Naval aviators, hypothesizing that pilots would demonstrate superior DVA relative to non-pilot personnel. A secondary aim was to explore the relationship between flight hours and DVA performance in pilots, along with evaluation of other demographics.

This study included 96 participants, 58 rotary wing pilots and 38 non-pilot maintenance crew members, from Naval Air Station North Island and Marine Corps Air Station (MCAS) Miramar. All participants were active duty service members who voluntarily completed a DVA assessment under the Naval Medical Center San Diego IRB protocol NMCSD.2021.005 as a part of a larger clinical human performance program. Participation was open regardless of age or sex, and recruitment occurred through word of mouth via squadron leadership and Naval Medical Center San Diego (NMCSD) briefs. Dynamic visual acuity was assessed using a computerized test validated in previous NIH Toolbox studies. This required static head movements and horizontal head movements that exceeded 180 deg/sec while identifying briefly presented optotypes. Independent t-tests and chi-square tests were used to compare demographics and visual acuity between groups. A linear model controlled for age and static acuity when comparing DVA scores. Among pilots, Pearson correlation assessed the relationship between flight hours and DVA.

There were no significant differences in demographics or static visual acuity between pilots and non-pilots. Pilots demonstrated significantly better DVA (0.15 ± 0.08 LogMAR) than non-pilots (0.22 ± 0.22 LogMAR), even when adjusted for age and static acuity (P = .01). Static acuity was strongly related to DVA (Beta = 0.65, P < .0001), whereas age was not. Among pilots, flight hours (mean = 916 ± 748 hours) were not correlated with DVA performance.

This study found that rotary wing Naval aviators exhibit superior DVA compared to non-pilots. These findings highlight potential vestibulo-ocular adaptations potentially from the constant occupational demands of aviation or because of the competitive selection process Naval aviators face. Although no correlation was found between flight hours and DVA, further longitudinal studies are needed to clarify whether DVA changes with time or exposure. This study is a first step toward bench marking and attempting to quantify the difference in DVA in pilots and non-pilots. Looking forward, DVA can play a crucial role in understanding the health of pilots' vestibular systems, while also maximizing their performance and safety in the aircraft. Future studies should look to track DVA changes over pilots' careers or following vestibular injuries, while also expanding to other aviation communities.