Abstract
Purpose :
The optical testing requirements of plano-protective eyewear in national/international standards rely on subjective evaluation methods that are negatively impacted by factors such as differences in accommodation, depth of focus, field of view, criteria and resolving power of the telescope-human observer system. These challenges can lead to significant variation in the testing results provided by different test laboratories. This study examined how observer differences could affect the results by evaluating the interrater reliability of refractive measurements of plano-protective eyewear using the ANSI Z87.1 (2020) telescope approach.
Methods :
Spherical and astigmatic power measurements were performed by two experienced observers on the left oculars of 52 pairs of military plano-protective eyewear in accordance with the method described in the ANSI Z87.1 standard. The observers were blind to each other's results. Briefly, the objective lens of a calibrated 8x telescope was mounted 35 feet from a combined sunburst-resolution test pattern in a controlled laboratory environment. The data was analyzed using a multiple rater, absolute-agreement, 2-way mixed-effects intraclass correlation (ICC) model for the spherical and astigmatic power measurements. SPSS-V26 was used for all statistical analysis and p<0.05 was used to determine statistical significance.
Results :
The mean (±SD) refractive powers of the eyewear for raters 1 and 2 were spherical -0.005(±0.019), -0.006(±0.02) and astigmatism 0.031(±0.015), 0.026(±0.016), respectively. There was good reliability between the spherical power measurements, with an ICC of 0.813 and 95% confidence interval from 0.674 to 0.893 (p<0.001). The reliability between the astigmatic power measurements was lower. The ICC was 0.531 with a 95% confidence interval from 0.191 to 0.729 (p<0.005).
Conclusions :
The ANSI Z87.1 telescope approach may provide reliable estimates of spherical power between raters for plano-protectors but less reliable interrater estimates of astigmatic power when using the same telescopic system. Objective refractive power measurement methods may improve this reliability further.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.