Objective To perform an objective evaluation of the non-invasive tear break-up time (NITBUT) and lipid layer interferometry in normal children.

Methods Children with no known ocular surface disease or anterior segment abnormality were evaluated. We excluded patients with disorders affecting lid margins or tear film composition. NITBUT and lipid layer interferometry were performed using a Keeler tearscope mounted on a slit lamp. The time from eye opening to the first distortion of the grid was noted. The average of three readings was taken as the NITBUT.

Results Thirty-six children (71 eyes) were included (mean age 7.64 years, range 2.16–15.83 years). Mean NITBUT was 21.76±4.06 s (range 14.9–30.95). This is significantly higher in comparison to recent adult studies utilising the tearscope. Twenty-four children allowed tearscope lipid layer interferometry. Eighteen demonstrated grade 1 and six demonstrated grade 2. These grades are within the normal tear film range.

Conclusions To our knowledge, this prospective study is the first to evaluate NITBUT in normal children. The results demonstrate that NITBUT is greater in children in comparison to adults. These normative data are a useful benchmark for further research into tear film instability in children.