Comment on: Serum vitamin D levels in children with vernal keratoconjunctivitis – A study from a tertiary care pediatric hospital of North India

Dear Editor, We read the article by Wadhwani et al.[1] published in the India Journal Of Ophthalmology in the May 2024 edition with great interest. The authors have looked into the association between serum vitamin D levels and the severity of Vernal keratoconjunctivitis (VKC) in pediatric patients. The article gives an insight into the role of vitamin D in the causation and treatment of VKC. However, there are a few concerns that need to be addressed to clarify the situation. The concerns are mentioned below: Sun exposure affects serum vitamin D levels.[2] The author should have matched the control and study arm as far as sun exposure is concerned. This would eliminate the confounding effect of sun exposure on serum vitamin D. The authors have mentioned that the control arm had no ocular complaints, except refractive error. However, the authors did not mention the status of refractive error in the study arm. Literature suggests that myopia is likely associated with decreased serum vitamin D levels.[3] Nonmatched groups could have induced bias. The groups are not gender matched. A gender bias is likely to arise. In the study group, a large number of participants are male. Literature suggests that males have consistently lower vitamin D levels than females.[4] The confounding effect of gender on serum vitamin D could have been abolished by gender matching. The authors should also consider the topical medication details during recruitment. A relatively milder-looking disease at presentation might be a recent-onset resolving VKC on topical steroids or antihistamines. This might give falsely high or low serum vitamin D levels associated with mild-appearing disease form. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship: Nil. Conflicts of interest: There are no conflicts of interest.