Baseline Age, Axial Length May Have Implications for Orthokeratology Treatment

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.