AIM: To investigate the effects of long-term orthokeratology lens wearing on corneal morphology, corneal biomechanics and objective visual quality.

METHODS: A retrospective study was conducted to collect 33 myopic patients(60 eyes), including 19 males(35 eyes)and 14 females(25 eyes), mean age 11.80±1.51 years old, with an average equivalent spherical lens of -3.25±0.69D, who had been wearing orthokeratology lens for 2a from October 2019 to December 2020 in our hospital. Relevant data were collected before wearing and 2a after wearing. The radius of curvature(ARC and PRC), the thickness of the thinnest cornea(THP)and the index of comprehensive deviation analysis of corneal dilation(BADD)were measured by Pentacam anterior segment analysis system. Corvis ST biomechanical analyzer measured non-contact biomechanical corrected intraocular pressure(blOP), maximum deformation amplitude(DA), maximum reverse radius(HCR), ratio of deformation amplitude between apex and 1mm(DR), hardness parameters(SPA1), and corneal biomechanical parameters(CBI). The biomechanical index(TBI)of CT scan was obtained by the combined diagnosis system of Pentacam and Corvis ST. OQAS-II objective visual quality analysis system measured modulation transfer function cutoff frequency(MTF cutoff), Stryl ratio(SR), objective scattering coefficient(OSI)and OV value(OV100%, OV20% and OV9%). The above parameters were compared before and continuously wearing orthokeratoscope for 2a.

RESULTS: After 2a of wearing orthokeratology, ARC increased, THP decreased, and BADD increased(t=-9.38, 2.85, -13.08; all P<0.05), while there was no significant difference between PRC and before wearing(t=1.49, P>0.05). DA increased and HCR decreased compared with before wearing orthokeratology lens(t=-2.37, 2.28; all P<0.05), but bIOP, DR, SPA1, CBI and TBI showed no difference(t=1.36, -1.87, 1.27, -0.95, -1.49; all P>0.05). SR was higher than before, OV20% and OV9% were lower than before(t=-5.31, 8.37, 2.34; all P<0.05), MTF cutoff, OSI and OV100% had no difference compared with before(t=-1.57, -1.35, 1.11; all P>0.05).

CONCLUSION: Long-term wearing of orthokeratology lens changed the morphology of the anterior corneal surface, but had no significant effect on the corneal biomechanics, and the objective visual quality of patients was improved during the day, but decreased at night.