To evaluate the effect of orthokeratology lens (OK) on the myopic progression of the uncorrected eye in children with unilateral myopic anisometropia.

In this retrospective study, children with unilateral myopic anisometropia (the difference of spherical equivalent refraction1.00 D) who were corrected with OK or single vision glasses for the first time in the Eye Hospital affiliated to Wenzhou Medical University from 2017 to 2020 were included. The spherical equivalent of myopia ranged from -4.00 to -0.75 D and the follow-up time was about 1 year. There were 50 children in OK group. The myopic eyes corrected with an OK were classified into OK-myopia group and the nonmyopic eyes were classified into OK-nonmyopia group. There were 54 children in spectacles group (SP group), which was also divided into the myopic group (SP-myopia group) and the nonmyopic group (SP-nonmyopia group). Paired t-test and multiple linear regression were used to observe the changes of axial length (AL), AL difference and corneal curvature.

(1)AL change: the AL of the OK-myopia group and OK-nonmyopia group increased by (0.13±0.19) mm and (0.43±0.25) mm respectively, and the differences were statistically significant (t=-6.45, P<0.001); the AL of the SP-myopia group and SP-nonmyopia group increased by (0.33±0.19) mm and (0.27±0.22) mm respectively, and the differences were not statistically significant. The AL elongation of the OK-myopia group was significantly slower than that in the SP-myopic group (β=-0.11, P=0.006), and the AL elongation of the OK-nonmyopia group was significantly faster than that in the SP-nonmyopic group (β=0.16, P=0.001). For the OK-nonmyopic group, there was a linear correlation between the AL elongation () and the age (X) : =-0.104X+1.564 (R²=0.27, P<0.001). (2)Change of AL difference: the change of AL difference of OK group decreased from (1.06±0.41) mm to (0.77±0.46) mm (t=6.65, P<0.001); there was no significant change in AL difference during one year in SP group, from (0.81±0.34) mm at baseline to (0.87±0.35) mm. (3) Corneal curvature: the keratometry at the flatest meridian (Kf) of the OK-myopia group changed from (42.42±1.30)D to (40.73±1.33)D, and the difference was statistically significant (t=12.76, P<0.001); the Kf of the OK-nonmyopia group changed from (42.31±1.30)D to (42.18±1.27)D, and the difference was statistically significant (t=3.08, P=0.003). There were no significant differences during one year for the Kf of the SP-myopic group and the SP-nonmyopic group.

Monocular orthokeratology treatment could effectively control the progression of myopia in unilateral myopic anisometropia, but may accelerate the progress of myopia in the contralateral eye for some young patients. The younger the age, the faster the progress.

myopia; anisometropia; orthokeratology