Accommodation and binocular vision changes after wearing orthokeratology lens in 8- to 14-year-old myopic children

Purpose The study aimed to observe and analyze the dynamic accommodation and binocular vision changes in myopic children after they switched from spectacles to orthokeratology (ortho-k) lenses. Methods Thirty-six myopic children aged 8-14 years were enrolled in this prospective, self-controlled study from West China Hospital. General information was gathered, and examinations were performed at baseline and at 1, 3, 6, and 12 months after switching to ortho-k lenses. The examination included assessments of distance/near visual acuity, distance/near horizontal and vertical ocular alignment, distance/near horizontal vergence range, accommodative amplitude, monocular/binocular accommodative facility, accommodative response, positive and negative relative accommodation (PRA/NRA), accommodation convergence/accommodation (AC/A), stereopsis, and reading ability. Results After the children switched to ortho-k lenses, distance and near ocular alignment showed an exophoric shift (distance: p = 0.001, near: p = 0.002), and the horizontal vergence range decreased by different degrees (convergence: distance blur point ( p = 0.002), distance break point ( p = 0.005), near blur point ( p = 0.011), near break point ( p = 0.043); divergence: distance break point ( p < 0.001), distance recover point ( p < 0.001), near recover point ( p = 0.005)). The stereopsis ability ( p < 0.001), monocular/binocular accommodative facility ( p < 0.001), and PRA ( p = 0.010) increased. The accommodative lag ( p < 0.001), accommodative amplitude ( p < 0.001), and calculated and gradient AC/A (calculated: p = 0.001, gradient: p = 0.025) decreased. The adjusted horizontal and vertical reading times and their ratio decreased (all p < 0.001). Conclusion The subjects showed distance and near exophoric shifts after switching to ortho-k lenses; improvements in accommodative function, stereopsis, and ocular motility; and a decrease in the binocular horizontal vergence range. The relationships between these changes and the ortho-k myopic control effects require further investigation.