Evaluation of Infant Accommodation Using Retinoscopy and Photoretinoscopy

PURPOSE: 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. METHODS: 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. RESULTS: 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). CONCLUSION: 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.