AIM:To study the effects of long-term wearing monocular orthokeratology on ocular surface.

METHODS: A retrospective study was conducted in patients with unilateral myopia(The contralateral eye of each patient was emmetropic.)who used orthokeratology lens for more than half a year. The patients were recruited from January 2013 to December 2015, in ophthalmological clinic, 101 Hospital of PLA, Wuxi. The tear break-up time(BUT), basal tear secretion, central corneal thickness, corneal endothelial cell density, conjunctival congestion and corneal epithelium fluorescein staining were observed before wearing orthokeratology and at different time points during wearing orthokeratology.

RESULTS: Fifty-three young patients(53 eyes)with long-term wearing a monocular orthokeratology lens were observed, whose ages were 10.43±1.70 years old and their spherical equivalents(SEs)were -3.37±1.50D. For the myopic eyes, after 1-week treatment of monocular orthokeratology, the BUT was shortened, but there was no significant difference compared with those after 1-month, 3-month, 6-month treatment of monocular orthokeratology(P>0.05). For the emmetropic eyes, there was no significant difference in changing the BUT at above different time points(P>0.05). There was no significant difference in the value of basal tear secretion at those time points between two different kinds of eyes(The myopic eyes with orthokeratology and the emmetropic eyes without orthokeratology)(P>0.05). Compared with before wearing orthokeratology lens, there was no significant difference in both corneal center thickness and corneal endothelial cell density at those time points after wearing orthokeratology lens(P>0.05). After wearing orthokeratology lens, the corneal epithelial stain was mostly Ⅰ dyed. After 1wk, 1, 3 and 6mo respectively, the Ⅰ dyed amounts were 10 eyes(19%), 6 eyes(11%), 8 eyes(15%), 6 eyes(11%),the Ⅱ dyed amounts were 1 eye(2%), 0, 0, 1 eye(2%). The conjunctival congestion(score 1)showed up on 10 patients after wearing the orthokeratology lens. After all the 10 cases stopping wearing orthokeratology lens, but taking some antibiotics and corneal repair agents, the corneal epithelium stain disappeared and the conjunctival congestion faded away. For the emmetropic eyes, no obvious conjunctival congestion was observed during the observation period, and the corneal epithelial stain was 0.

CONCLUSION: Continuous wearing orthokeratology can cause the decrease of the stability of tear film. And it also affects the conjunctiva and corneal epithelium by degrees. But it has no significant effect on tear secretion, corneal thickness and corneal endothelial cells. There will be no apparent ocular surface damage on non-wearing eyes.