AIM: To measure the tear film thickness when with a good fitted night wear orthokeratology lens in youth, and observe the change of corneal parameters.

METHODS: From July 2015 to August 2016, 51 eyes of 26 teenagers with myopia who would wear orthokeratology and accept regular follow-up were enrolled. The mean spherical equivalent refraction of teenagers was -2.78D±1.53D(-1.00D to-6.00D)before wearing orthokeratology, and the mean astigmatism was 1.29D±0.61D(0 to -2.68D). The tear film thickness were measured by optical coherence tomography(OCT)when the eyes wearing orthokeratology for 1mo. The surface regularity index(SRI)value was measured by corneal topography to compare its relationship with the tear film thickness and the changes of corneal anterior surface parameters during the period of wearing lens were observed.

RESULTS: At 1mo after wearing orthokeratology, the mean tear film thickness of right eyes was 230.09±10.40μm, and that was 224.38±10.57μm of left eyes. The mean tear film thickness was 228.75±9.66μm in male eyes and that was 224.80±6.74μm in female eyes. The mean tear film thickness of all eyes was 227.05±10.29μm, and the mean SRI value was 0.16±0.14. There was no correlation between tear film thickness and SRI value(P>0.05). The FK value, SK value and average K value from before wearing to after wearing for 2d and 1wk gradually decreased, the difference was statistically significant(P<0.05). There was no statistical difference among wearing for 1wk, 1, 3 and 6mo(P>0.05).

CONCLUSION: OCT can be used as a safe and reliable method for measuring the thickness of the tear film space during the wearing of orthokeratology, which may be of certain value for the safety assessment of the long term wearing of orthokeratology. Orthokeratology works very quickly, corneal curvature decreases rapidly 2d after wearing and stabilizes during the period.