A retrospective cohort study on orthokeratology for high myopia progression

Objective To study the therapeutic effect and safety of orthokeratology in the teenagers with high myopia. Methods A retrospective cohort study was carried out.The clinical data of 120 eyes from 60 high myopia patients wearing orthokeratology contact lens for 1 year in Henan Eye Hospital from June 2013 to June 2014 was analyzed, and the data of contemporaneous 118 eyes from 59 matched high myopia patients wearing conventional glasses were used as controls.The initial spherical equivalent (SE) of all the patients was -6.00 to -9.00 D. The maximum correction amplitude of the orthokeratology contact lens was set as 6.00 D based on the Regulation of China Food & Drug Administration.The contact lenses were worn for 1 month firstly and then the conventional glasses were used at daytime and contact lenses were consecutively worn at night for 1 year in the contact lenses group, and only glasses were worn in the conventional glasses group.The uncorrective visual acuity (UCVA), SE, corneal fluorescein staining were examined 1 week, 1 month, 3 months, 6 months and 12 months after wearing lenses.The changes of corneal endothelial cells were examined 6 and 12 months after wearing lenses. Results The UCVA was improved and SE was reduced 1 month and 3, 6 and 12 months after wearing lenses in comparison with 1 week after wearing lenses in the contact lenses group (all at P 0.05). Compared with wearing contact lenses, the SE was increased in various time points after wearing glasses in the conventional glasses group (all at P<0.01). The axial length and SE extended by (0.08±0.12)mm and (0.19±0.21)D in the contact lenses group and those in the conventional glasses group were (0.29±0.14)mm and (0.69±0.27)D, showing significant differences between the two groups (t=10.024, 5.691, both at P<0.01). No significant differences were found in corneal endothelial cell density, percentage of hexagonal cells and coefficient of variation of corneal endothelial cells in various time points after wearing contact lenses (corneal endothelial cell density: Fgroup=0.090, P=0.769; Ftime=0.133, P=0.563.percentage of hexagonal cells: Fgroup=0.071, P=0.836; Ftime=1.091, P=0.203.coefficient of variation: Fgroup=0.107, P=0.734; Ftime=1.948, P=0.156). The incidence of corneal fluorescein staining was 31.67% in the contact lens group, which was much higher than 3.51% in the conventional glasses group (χ2=97.910, P=0.001). Conclusions Compared with wearing only conventional glasses, orthokeratology can improve UCVA and control axial length extension in juvenile with high myopia, but orthokeratology is more likely to damage the corneal superficial layer. Key words: Orthokeratology; Contact lens; High myopia; Corneal endothelial cells; Axial length; Retrospective study