Effect of Eyepiece Focus on Visual Acuity Through ANVIS Night Vision Goggles During Short - and Long-Term Wear

摘要

The eyepiece lenses of ANVIS night vision goggle are ostensibly adjusted for optimum visual acuity (VA). Many users however do not adjust the eyepieces competently. This paper examines whether a single-focus eyepiece is capable of producing satisfactory VA while maintaining comfortable vision over extended periods. In a short-term ANVIS wear study, a range of eyepiece focus produced comparable VA independent of luminance and contrast. The single best- overall eyepiece focus produced vision equal to, or better than, that of subject-adjusted eyepieces, producing VA within 2% of optimal. However, zero diopter eyepieces reduced VA by 10%. In a long-term ANVIS wear study, - 1.5 diopter eyepieces caused half of the subjects to complain of blurred or uncomfortable vision. These studies indicate -0.75 diopter eyepieces provide optically- corrected ANVIS users with near optimal binocular VA and satisfactory visual comfort during extended ANVIS use.