FOCUS ADJUSTMENT EFFECTS ON VISUAL-ACUITY AND OCULOMOTOR BALANCE WITHAVIATOR NIGHT-VISION DISPLAYS

Sixteen U.S. Army aviators, who were given training on focus adjustmen t technique with aviator night vision goggles (NVG), showed an Improve ment in visual acuity with focus adjustment compared to a fixed infini ty focus control. The long-term effect of focus adjustment on vision w as not measured; however, adjustment accuracy was found to be generall y within acceptable limits based on computer modeling and available ph ysiologic data. Fixed focus eyepieces that tire set to a low minus pow er may partially compensate for instrument myopia, but they may not op timize visual acuity to the extent that adjustable focus eyepieces do. Eyepiece adjustment proficiency with present night vision devices can he improved through training that emphasizes focusing to the least po ssible minus dioptric power. Future night vision displays can minimize focus misadjustment by providing a tactile zero marking, a limited di optric adjustment range, and a focusing knob capable of finer adjustme nt than is available with current NVG's.