Evaluation of Infant Accommodation Using Retinoscopy and Photoretinoscopy

Abstract

To compare PlusOptix PowerRefractor (PR) and Monocular Estimation Method (MEM) for measurement of infant accommodation and to assess the usefulness of applying individual calibration factors to PR data. Subjects were 41 infants aged 3 to 12 months. Accommodative response was measured by MEM and PR at 33 and 57 cm, acuity by Teller Acuity Cards, and cycloplegic refractive error (RE) (tropicamide 1%) by retinoscopy (Wet Ret) and PR (PR C). Monocular wear of a +2.00 diopter (D) and +4.00 D lens established a PR calibration factor for each subject. The median individual calibration slope was significantly different from 1.0 (+0.91; Wilcoxon signed-rank test: p = 0.03), yet there was no correlation between individual calibration slopes and the difference in RE by Wet Ret and PR C (rs = 0.05, p = 0.76). For 19 infants with an accommodative response slope by PR of >0.50, the mean lag was not significantly different between methods (0.50 D PR, 0.48 D MEM; p = 0.92; 95% LoA = +/-1.78 D). Despite the improvement in acuity with age (rp = -0.56, p < 0.0001), neither age nor acuity had a significant effect on accommodative error. Lag was greater at 57 cm (0.69 D) than 33 cm (0.30 D, F1, 18 = 6.3, p = 0.022), but lag was unrelated to RE (F1, 17 = 3.3, p = 0.09). Accommodative response slopes for boys were larger (1.5) than for girls (1.0; F1, 17 = 9.5, p = 0.007). MEM and PR provided similar estimates of RE and of accommodative lag once the PR data were screened for inattention using an accommodative response slope criterion. Adult-like accommodative responses between 3 and 12 months of age suggest that acuity at these ages is not limited by accommodative immaturity. Further, mature accommodation may attenuate RE-related defocus signals for emmetropization.