A novel comparative study of inflammatory cytokines through non-invasive tear analysis in children with myopia versus emmetropia

Objective: Childhood myopia is a complex disorder with rising prevalence. Given that progressive myopia has been observed in inflammatory conditions such as keratoconus and uveitis, we conducted noninvasive tear film analyses on emmetropes, myopes, and hyperopes to compare their inflammatory cytokine profiles. Design: This was a prospective, cross-sectional study. Participants: Children aged 8 to 15 years were included in the study with appropriate Institutional Review Board approval. Children with coexistent ocular or systemic conditions other than refractive error and dry eye were excluded. Group 1—emmetropes with a spherical equivalent refraction (SER) of ± 0.5 D (30 eyes), Group 2—moderate myopes with a SER between –0.50 D and –6.00 D (39 eyes), and Group 3—high myopes with a SER of ≤–6.00 D (25 eyes). Methods: All participants underwent complete ophthalmic evaluation. An ocular surface disease index and lifestyle questionnaire were administered. Tear film evaluations included measuring tear meniscus height and tear film break-up time were performed. A second masked examiner collected tear samples using a Schirmer's tear strip, which was then stored at –80°C and analyzed via immunoassay. Main Outcome Measures: Tear fluid levels of the inflammatory markers IL-1β, IL-10, IL-6, MMP-9, ICAM-1, IL-17A, TNF-α, and VEGF-A were compared among the three groups. Results: The mean age was 12.4 ± 2.6 years. All inflammatory cytokines, except IL-17 and VEGF-A, showed positive associative trend in moderate and high myopes compared to emmetropes. After adjusting for age and multiple comparisons, TNF-α and ICAM-1 were significantly associated with myopia. Dry eye disease was significantly associated with raised IL-1β, IL-6, and IL-10. Conclusions: This study demonstrated a trend of increased inflammatory mediators in the tears of children with high and moderate myopia, with significant levels of TNF-α and ICAM-1, suggesting that inflammation may be associated with myopia.