The Influence of Overnight Orthokeratology on Ocular Surface and Dry Eye-related Cytokines IL-17A, IL-6, and PGE2 in Children

Objective: To investigate the effect of overnight orthokeratology (OOK) on the ocular surface and dry eye-related cytokines in children.

Methods: A non-randomized, prospective pilot study was conducted including sixty myopes treated with OOK and sixty age-matched spectacle wearing participants. The following tests were performed before and after 1, 3, 6 and 12 months: ocular surface disease index (OSDI), noninvasive tear breakup time (NITBUT), tear meniscus height (TMH), corneal fluorescein staining (CFS), meiboscore using noncontact meibography. Then the concentrations of interleukin-17A (IL-17A), interleukin-6 (IL-6), and prostaglandin E2 (PGE2) in tear samples were detected with a multiplex immunobead assay at different time points.

Results: All parameters had no statistical differences between the two groups prior to treatment. No adverse events were observed except trace to moderate corneal staining and allergic conjunctivitis in the treatment group. NITBUT significantly decreased after 6 and 12 months OOK wearing (P = 0.003 and P = 0.001, respectively). After wearing OOK there was a significant increase in CFS at each follow-up time point compared with baseline (P = 0.023, P = 0.016, P = 0.001, and P < 0.001at 1, 3, 6, and 12 months, respectively). The upper meiboscore and the total meiboscore increased gradually and peaked at 12 months of OOK (both P < 0.001). The concentration of the three cytokines in the treatment group significantly increased after OOK wearing. These increases occurred at different time points: IL-17A increased significantly 3 months after OOK, IL-6 at 6 months, and PGE2 at 12 months (all P < 0.001). However, there were no significant changes in the above parameters in the control group. There were no significant differences in the OSDI or TMH at any follow-up time point compared to baseline in both groups (both P > 0.05).

Conclusions: Short-term OOK may reduce the stability of the tear film and increase damage to the corneal epithelium. Long-term OOK could induce ocular inflammation through the disruption of meibomian glands.