Repeatability of pupil size measurements with NIDEK OPD‐Scan III in myopic children

Abstract

AbstractObjectiveTo investigate the repeatability of pupil size measurements, determined from the NIDEK OPD‐Scan III, of myopic eyes in children wearing single‐vision spectacles (SVS), undergoing orthokeratology (OK) and receiving combined treatment of 0.01% atropine and orthokeratology (AOK).MethodsA single examiner took two sets of mesopic pupil size measurements from the right eyes of 80 children (SVS:16, OK: 34, AOK: 30) (mesopic 1 and mesopic 2) and two sets of photopic (photopic 1 and photopic 2) pupil size measurements (internal light source) using the NIDEK OPD‐Scan III. Each set was taken at a single visit, 15 min apart. Subjects in the OK and AOK groups had undergone treatment for at least 6 months, and the SVS subjects had no previous myopia treatment other than wearing spectacles. Repeatability of measurements was analysed using intraclass correlation coefficient (ICC), Bland‐Altman (BA) plot, and coefficient of repeatability (CoR).ResultsMesopic 1 and 2 values were not significantly different among the three groups (p = 0.56, 0.77), hence the data were pooled for each set of measurements (mean [±S.D.] values were 7.09 ± 0.61 and 7.12 ± 0.61 mm, respectively) for further analyses. ICC for repeated mesopic pupil size measurements was 0.98 (95% CI, 0.98–0.99). No significant correlation was found between the means of the mesopic 1 and 2 measurements and their differences (Pearson's r = −0.02, p = 0.83). A BA plot also demonstrated narrow 95% limits of agreement, with a CoR of 0.28 mm.Mean photopic 1 and 2 measurements for the AOK group (3.74 ± 0.46; 3.73 ± 0.43 mm, respectively) were significantly larger (p = 0.01; 0.009) than those of the SVS and OK groups, but no significant difference was found between the latter two groups (p > 0.05). Hence, photopic 1 and 2 measurements for the SVS and OK groups were pooled (SVS‐OK) for further analyses. ICC for repeatability of the photopic measurements was 0.98 (95% CI, 0.96 to 0.99) for the SVS‐OK and AOK groups. The differences between photopic 1 and 2 measurements were not significantly correlated with their means, either in the AOK group (Pearson's r = −0.25, p = 0.19), or in the pooled SVS‐OK group (Pearson's r = −0.04, p = 0.78). BA plots also showed narrow 95% limits of agreement, and CoR was 0.25 mm and 0.23 mm in the AOK and pooled SVS‐OK groups, respectively.ConclusionMesopic and photopic pupil size measurement using the NIDEK OPD‐Scan III was highly repeatable and suitable for use on children.