TIME-LIMITED VISUAL RESOLUTION IN PILOT TRAINEES

Superior vision is needed for piloting aircraft in military and civili an environments, Although visual evaluations of potential pilots typic ally are conducted with no limit on viewing time, aviation and related occupations require superior vision under time-limited viewing condit ions, and assessment of this capability is needed, The purpose of this study was to evaluate time-limited visual resolution in pilot trainee s. A forced-choice letter recognition task was used to measure visual acuity (VA) and small letter contrast sensitivity (SLCS) in 37 trainee s who had satisfied all vision requirements for pilot training. VA and SLCS were highly correlated (r = 0.76), indicating that the two tests measure similar aspects of visual resolution, However, although VA sc ores were distributed across 0.16 log units (two lines of letters on a VA chart), SLCS scores varied across 0.35 log units, which is nearly four lines on the SLCS chart, The variation in SLCS performance could be explained, in part, by subtle refractive error in pilot trainees, T he results exemplify differences in performance among visually qualifi ed trainees, and underscore the need for proper refractive correction, SLCS is a useful screening test for identifying subtle changes in vis ion that herald the need for optical or medical intervention.