Characterization of tear function tests in a healthy pediatric population in Bogota, Colombia

Methods : This is a cross-sectional study in 60 healthy children between 7-17 years old. Exclusion criteria: local or systemic disease, use of medications and contact lenses use. It was approved by our institutional ethic committee. Informed consent and assent were obtained. Performed tear function tests were: evaluation of the palpebral edge, blink frequency measurement, tear meniscus height, NITBUT, lipid layer thickness, conjunctival redness, tear osmolarity, meibography and lissamine green and fluorescein staining. Statistical analysis using R Core program obtained means and frequencies. Results were compared to adult normal values. Mixed-cluster methodology was used, determining three device preference groups: TV, smartphone and computer and tablet.

Results : Mean age was 12 years old, 41.6% were females. OSDI results mean was 9.5. Daily screen time was 335.5 minutes, being smartphone the most popular screen. Mean results of tear function tests were: paper blink frequency 6.8 times/minute, screen blink frequency 8.7 times/minute, palpebral edge was abnormal in 3 eyes, 49.16% had thin lipid layer, tear meniscus height 0.17 ± 0.04 mm, NITBUT 10.82 ± 5.37 seconds, nasal conjunctival redness 0.94 ± 0.37, temporal conjunctival redness 1.07 ± 0.41, tear osmolarity 304.35 ± 18,18 mmol, Schirmer 21.9 ± 10.51 mm, 70.8% had positive staining for Lissamine green and 47.4% for fluorescein, 61.1% had some grade of Meibomian gland loss and 31% some grade in all eyelids. We found a direct relation between age and tear meniscus height (p: 0.02), bigger tear meniscus height in boys than girls (p: 0.04), less tear meniscus height in children who use tablets than those who do not (p: 0.02), more conjunctival redness in boys than girls (p: 0.005) and more conjunctival redness in children who had positive fluorescein staining (p: 0.01). There was not statistical association between tear function test parameters and the three groups mentioned.

Conclusions : This is the first study including all tear function tests, in an attempt to describe normal values in healthy children in South America. Nevertheless, 100% of the participants reflected at least one tear function test altered, compared with adult normal values. This study opens the door to continue evaluating ocular surface in children.