Pay more attention to the patient’s skin color than that of the iris when dilating, study says. Photo: Getty Images.

Increasing skin pigmentation and crying have been found to significantly affect hypermetropic children who have been administered cyclopentolate and tropicamide. In a recent study, researchers compared the refractive outcome and residual accommodation of iris and skin pigmentation in these children on either of these medicines.

The study included 251 hypermetropic children who were classified according to iris and skin pigmentation (light, medium, dark) and received two drops of cyclopentolate 1% or one drop of cyclopentolate 1% and one drop of tropicamide 1%.

“Solid evidence is found for our hypothesis that skin pigmentation and not iris pigmentation is the decisive factor in the effectiveness of cycloplegics,” the authors concluded. “Besides the significant differences between the consecutive skin pigmentation categories in the subjects with a dark iris, we found after correction for skin pigmentation […] only 2.7% of variance in residual accommodation was explained by iris color.”

The underlying base of their findings is that melanocytes of pigmented children contain larger melanosomes and larger amounts of melanin.

The investigators also found that none of the children in the study cried or showed any resistance toward eye drop application. They noted this could be due to the participants’ older age compared with previous studies, one of which showed less hypermetropia in crying children with a dark iris and pigmented skin.

“Although in the present study none of the subjects cried or had resistance toward the eye drop application, it is important to realize that crying, especially in the darker pigmented subjects, results in significantly less hypermetropia in any intervention,” the authors explained. “Our study showed that cyclopentolate 1% combined with tropicamide 1% provides both statistically and clinically better outcomes when integrating the factor skin pigmentation for dark-irided subjects.”

“We recommend the combination of cyclopentolate 1% and tropicamide 1% as the first-choice regime,” they continued. “In subjects with a dark iris who have medium to darkly pigmented skin, the amount of residual accommodation is considerable, resulting in a significantly lower hypermetropic outcome. For this particular group of children, additional cycloplegic eye drops, especially in the presence of crying and/or (accommodative) esotropia, are necessary.”

They also suggest further research for this group of children is necessary to determine the optimal regime, taking into account crying during application, the risk for adverse reactions and the burden of repeated administration of eye drops.

van Minderhout HM, Joosse MV, Grootendorst DC, Schalij-Delfos NE. 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%. Acta Ophthalmologica. October 20, 2021. [Epub ahead of print].