Changes in choroidal thickness and axial length in adolescents with myopic anisometropia after orthokeratology treatment

AIM:To observe the changes of choroidal thickness(CT)and axial length(AL)in adolescents with myopic anisometropia before and after orthokeratology(OK lenses)treatment.METHODS: In this retrospective case-control study, 71 myopic participants who insisted on using OK lenses more than 6mo at night from June 2020 to September 2021 in Second People's Hospital of Shenzhen were enrolled. They were divided into three groups, including group A consisted of 31 myopic participants with non-anisometropic myopia with binocular lenses(A1 group: the right eyes, A2 group: the left eyes), group B consisted of 18 bilateral myopic anisometropes(B1 group: the eyes with high degree, B2: the eyes with low degree)and group C consisted of 22 unilateral myopic anisometropes(C1: the eyes with high degree, C2: the eyes with low degree). The length of axis, the CT values of subfoveal(SF)and the superior(S0.5, S1.0, S1.5), inferior(I0.5, I1.0, I1.5), temporal(T0.5, T1.0, T1.5)and nasal(N0.5, N1.0, N1.5)at 0.5, 1.0 and 1.5mm from the fovea before and after wearing lenses at 6mo were measured.RESULTS: After wearing lenses at 6mo, CT of all sites in group A1 was all thickening compared with that before wearing lenses(all P<0.05), CT of all sites in group A2 was all thickening compared with that before wearing lenses, there was no difference compared with that before wearing lenses except for the SF, S1.5, T0.5 and T1.5 sites of the CT, the rest of the sites were different before and after wearing lenses(all P<0.05), CT of T1.0, N1.5 and S1.5 sites in B1 group was thicker than that before wearing lenses(all P<0.05), there was no difference in CT of all sites of the patients in group B2 before and after wearing lenses(all P>0.05). Among them, the CT at SF, S0.5, S1.0, S1.5, I0.5, I1.0, I1.5, N0.5, N1.0 and N1.5 was thinner than before wearing lenses, but it was not statistically significant. There were differences in all sites of CT in group C1 compared with that before and after wearing lenses(all P<0.05), for the CT of group C2, all the other sites except the points T1.5 and S1.5 was significantly thickened compared with that before wearing lenses(P<0.05). The axis of patients in group B2 increased by 0.12±0.14mm after wearing lenses at 6mo compared with that before wearing lenses(all P<0.001). The axis of group C2 increased by 0.20±0.17mm after wearing lenses at 6mo compared with that before wearing lenses(all P<0.001). The interocular axial difference in group B and C decreased from 0.54±0.27, 0.88±0.39mm before wearing lenses to 0.47±0.20, 0.62±0.39mm after wearing lenses at 6mo(all P<0.05). There was no significant in the interocular axis difference of group A1 and A2 before and after wearing lenses(P>0.05).CONCLUSION: For adolescents with myopic anisometropia patients after long-term wearing OK lenses have CT thickening in high degree eyes, but no thickening in low-degree eyes, and even thinning. At the same time, wearing OK lenses can slow axis elongation and reduce interocular anisometropia difference in axis, which is an effective clinical method to control the development of anisometropia.