Effect of orthokeratology on axial length elongation in moderate myopic and fellow high myopic eyes of children

Clinical relevance The effects of orthokeratology (Ortho‐K) on myopic eyes was examined, providing confidence to optometrists applying Ortho‐K to high myopic and anisometropic children.Background Ortho‐K slows the progression of low to moderate myopia. The effectiveness of Ortho‐K in Chinese children with fellow moderate and high myopic eyes was determined.Methods This retrospective study included female (n = 35) and male (n = 30) children with moderate myopia in one eye (spherical equivalent refractive (SER) error ≤ −3.00 D, but > −6.00 D) and high myopia in the contralateral eye (SER error ≤ −6.00 D). Three age groups were included: 7–10-years (n = 18), 11–12-years (n = 21), and 13–15-years (n = 26). Baseline refraction and axial lengths were measured before fitting Ortho‐K lenses worn nightly for at least eight-hours, and after one-year.Results Axial length increased 0.14 ± 0.13-mm (mean ± standard deviation) and 0.13 ± 0.16-mm in the moderate and high myopic groups respectively (p = 0.78). For females, axial elongation in the moderate and high myopic groups was 0.10 and 0.08-mm respectively. For males, it was 0.19-mm in both groups. Axial elongation in 7–10‐year‐old children with moderate and high myopic eyes was 0.24 ± 0.14 and 0.21 ± 0.15-mm respectively. In 11–12‐year‐old children, it was 0.12-mm in both myopic groups. In 13–15‐year‐old children, it was 0.09-mm in both groups. In moderate myopic eyes, axial elongation in the youngest group was greater than the other two age groups (p < 0.01). In high myopic eyes, there were no differences among the age groups (p = 0.06).Conclusions Ortho‐K was equally effective in reducing myopic progression in moderate and in contralateral high myopic eyes. Axial elongation was greater for males than females. For both sexes, it decreased at the same rate with increasing age, regardless of difference in myopia.