Tear film stability in children: Age and sex associations explored through non-invasive tear break-up time.

Purpose: The stability of the tear film is crucial for maintaining good ocular health. Its assessment provides valuable insights into paediatric eye conditions. This study investigates the stability of the tear film in children and its association with predictive factors such as age and sex, for a better understanding of tear film dynamics in a paediatric population.

Methods: A cross-sectional study was conducted in a semi-urban area in northern Portugal. Tear film stability was evaluated using non-invasive tear break-up time (NIBUT) measured with Tearscope Plus. The evaluation was conducted subjectively, with measurements obtained exclusively in the right eye. The mean of three consecutive measures of the NIBUT was considered in the statistical analysis.

Results: A total of 2094 children (1072 females, 1022 males), with a mean age of 8.6 ± 1.3 years, were included. It was found a mean NIBUT of 14.8 ± 5.4 s (s), with no statistically significant difference between females (14.9 ± 5.4 s) and males (14.7 ± 5.4 s) (p = 0.407). Around 20 % of the children had a NIBUT < 10 s, and about 7 % had a NIBUT ≤ 5 s. A significant increase in NIBUT with age during the middle childhood stage (6 to 11 years old) was also found (p = 0.019), with NIBUT increasing from 14.1 ± 5.7 s in 6-year-olds to 16.3 ± 4.8 s in 11-year-olds (p = 0.006). However, when results were separated by the participants' sex, only the male group showed statistically significant differences (p = 0.021).

Conclusions: A significant increase in NIBUT was found during the middle childhood stage, primarily driven by male participants. These findings underscore the importance of considering age and sex in assessing tear film stability in paediatric populations.