Older baseline age (11-14 years) and longer axial length (AL) are associated with slower axial elongation in children undergoing orthokeratology (ortho-k) treatment for myopia, according to research published in Ophthalmic and Physiological Optics. Younger children (8-11 years) with a shorter baseline AL (<24.5 mm) may benefit from optimized lens designs or combination therapies, according to the report.
Researchers included 1176 children with myopia in the analysis and assigned them to treatment with ortho-k (n=588; mean age, 10.88 years; 300 boys) or spectacle lenses (n=588; mean age, 10.94 years; 298 boys) based on patient preference. All participants underwent a comprehensive eye examination consisting of cycloplegic refraction, visual acuity testing, slit-lamp evaluation, corneal topography and AL measurement at baseline.
AL elongation was measured during a 1-year follow-up visit. A subset of participants aged 8 to 11 years within the ortho-k group (n=150) who completed a 3-year follow-up were stratified into 1 of 3 subgroups according to baseline AL (group 1, AL <24.5 mm; group 2, 24.5 mm≤AL<26 mm; and group 3, AL ≥26 mm).
Participants who underwent ortho-k treatment experienced 39% slower axial growth compared with participants treated with spectacle lenses (0.19 vs 0.31 mm; P <.01). The AL growth at the 1-year visit was significantly associated with baseline AL among patients treated with ortho-k (r=-0.30, P <.01), but not in patients treated with spectacles (r=-0.04, P =.31).
A subgroup analysis of patients treated with ortho-k who completed 3-years of follow-up revealed faster axial elongation among participants with a shorter AL. Axial elongation was significantly faster in group 1 during the first (mean difference, 0.18 mm vs group 2; mean difference, 0.25 mm vs group 3; P <.01 for both) and second years (mean difference vs group 2, 0.10 mm; mean difference vs group 3, 0.09 mm; P <.01 for both), but not for the third year, according to the report.
“Considering the inter-individual variation in myopia progression after wearing ortho-k lenses, our results may offer a new perspective on myopia control using ortho-k, specifically for establishing individual guidelines for myopia management in children with different baseline characteristics,” according to the researchers.
Study limitations include a retrospective nature and failure to record baseline AL in the nasal and temporal gaze, corneal biomechanics, pupil size, and other factors that could affect myopia progression.
Lin W, Li N, Lu K, Li Z, Zhuo X, Wei R. The relationship between baseline axial length and axial elongation in myopic children undergoing orthokeratology. Ophthalmic Physiol Opt. Published online November 15, 2022. doi:10.1111/opo.13070