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Visual performance effects and user acceptance of the M43A1 aviation protective mask frontserts.

BACKGROUND
The initial M43 aviation protective mask was fielded without provisions for optical corrective devices. Contact lenses, an interim solution, were not entirely acceptable since a small segment of the population could not be fitted adequately with contacts. This study evaluated visual performance affects and user acceptance of the M43A1 mask with frontsert correction modifications.


METHODS
The investigation was divided into three phases: 1) a helicopter simulator evaluation designed to experimentally test the suitability of the M43A1 frontserts, both in single vision and bifocal forms, for use in the aviation environment; 2) a static cockpit evaluation, designed to identify aircraft-specific problems with the frontsert system; and 3) an inflight evaluation to examine the stability and usability of the frontserts under actual flight conditions. The subjects were 30 U.S. Army aviators (28 men and 2 women).


RESULTS
Objective data from flight simulation evaluations suggested there were no significant differences between flight performance with and without the mask, despite refractive status. Subjective data from static and flight evaluations reflected positive user acceptance of the new mask and frontserts. Problems may exist in smaller cockpits (OH-58 A/C, D), but evidence suggested that this may have been an artifact resulting from testing the mask while wearing protective body armor.


CONCLUSIONS
Within the range of flight conditions and profiles examined, the M43A1 frontsert system meets U.S. Army aviation needs for optical correction when mission requirements dictate flying with chemical-biological protective masks.