Vitamin D serum levels in children with vernal keratoconjunctivitis and disease control

The aim of this study was to evaluate whether the control of ocular symptoms with cyclosporine or with tacrolimus in eye drops allows to improve sun exposure and therefore serum level of vitamin D (VD; 25OHD), in the more severe forms of vernal keratoconjunctivitis (VKC). Out of 242 children followed for active VKC, 94 were treated with 1% cyclosporine or 0.1% tacrolimus eye drops, while the other 148 with mild VKC did not need to be treated with immunomodulators. VD serum levels were measured in spring and autumn in 71 children. In total, 60 of them were treated with cyclosporine eye drops (first group) and 11 (not responding to cyclosporine therapy previously) with 0.1% tacrolimus eye drops (second group) between March and November 2016. Pre-treatment median values of VD were 23.7 ng/mL in the first group and 23.8 in the second group, and post-treatment values increased up to 32.8 and 32.9 ng/mL, respectively. Before treatment, 33% presented a deficiency (25OHD < 20 ng/mL), and at the end of summer, only 4% were deficient. The overweight children had lower improvement in VD serum levels than children with a body mass index (BMI) lower than 85th percentile. Children in therapy with cyclosporine, but requiring the administration of local steroid therapy during the summer for control of the symptoms, showed a greater improvement in 25OHD serum levels in ng/mL (23-37 ng/mL) than children who did not require steroid therapy (24-35 ng/mL). Furthermore, there was a significant difference in change of 25OHD in children presenting limbal VKC (21-41 ng/mL) versus tarsal VKC (24-35 ng/mL) (P = 0.04). Our study suggests that ocular treatment carried out with immunomodulator eye drops could allow for an improvement in 25OHD serum levels. In children with active VKC and at risk of 25OHD deficiency, likely due to avoidance of sun exposure, the role of other risk factors (BMI, phototype and treatment) on 25OHD serum levels should be considered.