AIM:To observe the effect of different time of wearing overnight orthokeratology lens(OOK lens)on the meibomian gland and detection rate of demodex.

METHODS:Case-control study. Totally 47(91 eyes)patients who wearing keratoscopy were enrolled from June 2019 to December 2019 in Hanyang Aier Eye Hospital. According to the wearing time, they were divided into short-term group(wearing time <2a)and long-term group(wearing time≥2a). Meanwhile, patients wearing frame glasses with gender, age and diopter matching with the two groups above were selected as the control group. All patients had non-invasive tear film rupture time(NI-BUT)examination, meibomial gland infrared photography, bulbar redness score(BRS), and eyelash sampling.

RESULTS: The three groups of NI-BUT were 12.68±4.59s, 12.37±4.97s, 10.45±6.04s,(P>0.05). BRS respectively were 0.99±0.41, 0.90±0.37, 0.84±0.35,(P>0.05). Meibomian gland score for all three groups: 1(0, 1)(P>0.05). In the three groups, the detection rate and quantity of demodex were 42%, 1(1, 2); 39%, 2(1, 2); 33%, 1(1, 2),(P>0.05). Among the patients with corneal staining, 5 were mite positive and 11 were mite negative(P>0.05). Meibomian gland score: 4 eyes were 0 grade, 12 eyes were 1 grade above(P>0.05). Short-term group 6 eyes, long-term group 10 eyes(P>0.05).

CONCLUSION:There was no significant effect on meibomian gland, the detection rate and quantity of demodex in patients wearing OOK lens. Whereas no significant relationship between meibomian gland score/ demodex detection rate and corneal staining.