VISUAL PERFORMANCE WITH THE AVIATOR NIGHT-VISION IMAGING-SYSTEM (ANVIS) AT A SIMULATED ALTITUDE OF 4300 METERS

This study determined if visual performance with Aviator Night Vision Imaging System (ANVIS) was degraded by the degree of hypoxia experienc ed at the maximum flight altitude currently authorized (U.S. Army regu lations) without supplemental oxygen, Visual acuity and contrast sensi tivity with ANVIS were tested under simulated starlight and full moonl ight illumination in a hypobaric chamber: at ground level (93 m), 5 mi n and 30 min after ascent to 4300 m, and 10 min after return to ground level, Visual acuity was significantly (p < 0.05) de graded by a smal l amount (0.05 log minimal angle resolvable) after 30 min at 4300 m. c ontrast sensitivity was not significantly degraded at any time. No sig nificant difference between males (n = 11) and females (n = 6) on any measure of visual performance was detected, Females did have a signifi cantly lower percent oxygen saturation of hemoglobin compared with mal es at altitude (72% versus 80% after 30 min). The results suggests tha t visual acuity with ANVIS is degraded slightly after 30 min of exposu re to 4300 mr although lass than what would be expected with unaided n ight vision under these conditions.