Eye colour and skin pigmentation as significant factors for refractive outcome and residual accommodation in hypermetropic children: a randomized clinical trial using cyclopentolate 1% and tropicamide 1%

PURPOSE: To compare the refractive outcome and residual accommodation with respect to various degrees of iris and skin pigmentation in hypermetropic children using 2 drops of cyclopentolate 1% (C + C) or 1 drop of cyclopentolate 1% and 1 drop of tropicamide 1% (C + T). METHODS: Two hundred fifty‐one hypermetropic children were classified according to iris and skin pigmentation (light, medium, dark) and received randomized and double‐blind C + C or C + T. Refractive error (spherical equivalent, SEQ) was determined using the Retinomax‐K + 3. In 204 subjects, residual accommodation (RA) was determined using the PlusoptiX PowerRefractor. RESULTS: A linear mixed model with a light‐irided and light skin‐pigmented reference group receiving C + T (mean SEQ +3.10 ± 1.87D) indicated significant less hypermetropia in subjects with a dark iris having a medium‐ and dark‐pigmented skin in C + T, −1.02 ± 0.29 (−1.59/−0.45) and −1.53 ± 0.30 (−2.10/−0.95); and in subjects having a light‐, medium‐ and dark‐pigmented skin in C + C, −0.74 ± 0.34 (−1.41/−0.06), −1.26 ± 0.30 (−1.85/−0.66) and −1.84 ± 0.30 (−2.42/−1.26). Similar findings were present for RA. Our model with a light‐irided and light skin‐pigmented reference group receiving C + T (mean RA +0.84 ± 0.61D) indicated significantly higher RA in dark‐irided subjects with medium‐ and dark‐pigmented skin in C + T, +1.05 ± 0.19 (+0.67/+1.43) and +1.35 ± 0.20 (+0.9/+1.74), and in C + C, +1.13 ± 0.21 (+0.71/+1.55) and +1.90 ± 0.19 (+1.51/+2.28). CONCLUSIONS: We found solid evidence that skin pigmentation rather than iris pigmentation is the decisive factor for effectiveness of cycloplegics. Awareness of the limitations of cycloplegic regimens in dark‐irided/pigmented children is needed. Our study showed that cyclopentolate 1% combined with tropicamide 1% provides more accurate refractive outcomes both statistically and clinically integrating the factor skin pigmentation for dark‐irided subjects.