Authors: Bian Silin, Liu Hua, Lin Jiang
To evaluate the 1-year clinical outcome of orthokeratology contact lens wear and glasses wear for myopia in children, mainly focusing on the effects on the biological parameters of the eyeballs.
A randomized-controlled clinical study analyzed 200 eyes of 200 adolescent, with low and moderate myopia from January 2018 to August 2018 at Chengdu Aier Eye Hospital.The subjects were divided into an orthokeratology group and a spectacles group, 100 eyes in each group.The axial lengths (AL), central corneal thickness (CCT), anterior chamber depth (ACD), and crystalline lens thickness were measured and compared between the two groups before and 6 months, 12 months after wearing the lenses, and 1 month after stopping lens wear.This study conformed to the tenets of the Declaration of Helsinki.Written informed consent was obtained from each subject prior to entering the study cohort.The study protocol was approved by the Ethics Committee of Chengdu Aier Eye Hospital (No.01-1).
The overall difference in AL was statistically significant in the two groups at various time points(Fgroup= 4.617, P=0.043; Ftime=10.939, P=0.023). Compared with before wearing lenses, the AL was significantly lengthened in both of the groups at 6 and 12 months after wearing lenses and 1 month after stopping lens wear (all at P<0.05). There was no significant difference in AL between 1 month after stopping lens wear and 12 months after wearing lenses in the orthokeratology group (P>0.05). Twelve months after wearing lenses, the AL increases values of the orthokeratology group were significantly lower than those of the spectacles group ([0.13±0.06]mm vs.[0.29±0.08]mm) (t=16.000, P=0.002). The differences in CCT at time points in the two groups were statistically significant (Fgroup=2.297, P=0.013; Ftime=11.219, P<0.01). At 6 and 12 months after wearing the lenses, the CCT in the orthokeratology group was significantly thinner than that before lens wear (all at P<0.05). CCT showed no significant difference between 1 month after stopping lens wear and before wearing lenses in the orthokeratology group (P>0.05). There was no statistically significanant difference in the ACD between the two groups at time points (Fgroup=4.226, P=0.051; Ftime=3.208, P=0.057). The overall differences in crystalline lens thickness at time points before and after wearing lenses in the two groups were statistically significant (Fgroup=13.13, P<0.01; Ftime=0.804, P=0.047). At 6 and 12 months after wearing the lenses and 1 month after stopping lens wear, the crystalline lens thickness in the orthokeratology group was significantly greater than that before lens wear and that in the spectacles group at the same time points (all at P<0.05). There was no significant difference in the crystalline lens thickness between 1 month after stopping lens wear and 12 months after wearing the lenses in the orthokeratology group (P>0.05).
Compared with wearing spectacles, orthokeratology lenses wear can effectively slow down the prolongation of the AL, decrease CCT reversibly and increase crystalline lens thickness in adolescent myopic subjects, but it has no significant effect on the ACD.