Kaleidos-based binocular vision analyzer for the estimation of refractive errors and horizontal ocular deviation in children

Abstract

ABSTRACT Clinical relevance Knowing the agreement and interobserver variability of the 2WIN-S photorefractometer with cycloplegic retinoscopy and prism cover test is important for judging the clinical usefulness of the device. Background This study aims to determine an agreement and interobserver reliability between 2WIN-S photorefractometer and cycloplegic retinoscopy for estimating refractive errors and between 2WIN-S and prism cover test for measuring horizontal ocular deviation in children. Methods Two groups of 129 and 64 participants (range, 5 to 16 years) were recruited for the agreement and interobserver reliability studies, respectively. Non-cycloplegic 2WIN-S refraction was compared with cycloplegic retinoscopy for low and moderate myopia and hyperopia. Similarly, corneal reflex-function (CR-function) of 2WIN-S was compared with prism cover test for horizontal ocular deviation. Bland-Altman plots were used to depict agreement, and the intraclass correlation coefficient (ICC) was used for determining interobserver reliability of repeated measures. Results The mean differences in spherical equivalent, J0 (Cartesian astigmatism) and J45 (oblique Jackson cross-cylinder) between cycloplegic retinoscopy and 2WIN-S were 1.10 (95% CI = 0.97 to 1.21, p < 0.001), −0.06 (95% CI = −0.09 to −0.03, p < 0.001) and 0.009 (95% CI = −0.01 to 0.03, p = 0.35), respectively. The overall median difference in the horizontal ocular deviation between prism cover test and 2WIN-S was −4.5 (Interquartile range = −12.0 to 4.0). For constant strabismus, this difference was insignificant (median= −2.0, interquartile range = −11.0 to 6.7, p = 0.19) between prism cover test and 2WIN-S. The ICC was high for the spherical equivalent (0.997; p < 0.001), J0 (0.932; p < 0.001) and J45 (0.901; p < 0.001), whereas it was low-to-moderate for horizontal ocular deviation (0.50; p < 0.001). Conclusion 2WIN-S refraction was in agreement with cycloplegic retinoscopy for low and moderate myopia and hyperopia, and requires an adjustment for the consistent differences between cycloplegic retinoscopy and 2WIN-S refraction. The measurement of constant strabismus with 2WIN-S is comparable to that of prism cover test.