Reproducibility of Night Vision Goggle Visual Acuity Measurements Using Landolt C's

摘要

The main purpose of the study was to determine reproducibility limits of night vision goggle (NVG) acuity measurement under relatively high and low illumination levels. Psychometric acuity functions of three observers were repeatedly measured using Landolt C's as stimuli. The reproducibility limits of the Snellen acuity value (20/xx) relating to 50, 75 and 95% correct (adjusted for chance) were then determined. Reproducibility limit is defined as approximately 95% of all pairs of replications (20/xx) from the same illuminance and same observer, generated on different days, should differ in absolute value by less than the reproducibility limit. It was determined that for the lower illumination (8.61E-4 lux) at 50% corrected for chance probability level, the reproducibility limit was 5.1 Snellen acuity (20/xx) and for the higher illumination (1.38E-2 lux), 2.5 Snellen acuity. These limits were 17% and 13% of mean acuity, respectively.