Comparison of therapeutic effect between regular spherical CRT and dual axis CRT on myopia with corneal astigmatism

Objective

To compare the therapeutic effect between regular spherical corneal refractive therapy (CRT) and dual axis CRT on myopia with corneal astigmatism.

Methods

A non-randomized controlled study was conducted.Aged 8 to 14 years old, forty-eight patients (48 eyes) wearing CRT orthokeratology enrolled from May, 2018 to December, 2018 in First Affiliated Hospital of Army Medical University were divided into dual axis CRT group (24 eyes) and spherical CRT group (24 eyes) according to their guardians’ willingness.After 1-year follow-up, the visual acuity, eccentricity distance in treatment area, annual axial growth and the corneal punctate staining incidence of the two groups were compared.The study followed the Declaration of Helsinki, and was approved by an Ethics Committee of First Affiliated Hospital of Army Medical University (No.KY201975). Written informed consent was obtained from guardians prior to any examination.

Results

The uncorrected visual acuity of the dual axis CRT group was better than that of the spherical CRT group at one week and one month after correction, and the differences were statistically significant (both at P<0.05), and there was no significant difference in uncorrected visual acuity between the two groups at other time points (all at P>0.05). The deviations of optical center in the spherical CRT group at each observation time points were significantly larger than that in the dual axis group (all at P<0.05), and the deviation was not obviously changed with time in both groups and there was no significant difference in deviation change between the two groups (F_time=2.301, P=0.074). The eccentricity was mainly in horizontal direction in spherical CRT group.The median annual axial growth was 0.12 (0.10, 0.45)mm in the dual axis CRT group and 0.14 (0.10, 0.46)mm in the spherical CRT group, with no significant difference between the two groups (Z=0.248, P=0.804). There was 4.2%(1/24) of the patients having grade Ⅲ-Ⅳ corneal punctate staining in the dual axis CRT group, and 25.0%(6/24) in the regular spherical CRT group, showing significant difference between the two groups (χ²=4.180, P=0.049).

Conclusions

For the treatment of myopia with astigmatism, dual axis CRT shows better centricity and safety than spherical CRT.

Myopia; Astigmatism; Orthokeratology; Axial length; Spherical; Dual axis