Control of myopia using orthokeratology lenses in Scandinavian children aged 6 to 12 years. Eighteen-month data from the Danish Randomized Study: Clinical study Of Near-sightedness; TReatment with Orthokeratology Lenses (CONTROL study)

Abstract

Purpose: To investigate the efficacy of myopia control defined by axial elongation and safety of orthokeratology lenses (OKL) in a Scandinavian (Danish) population.

Methods: Sixty Danish children aged 6-12 years with myopia ranging from 0.5 to 4.75 dioptres (D) spherical component and refractive astigmatism ≤2.5 D in both eyes were randomly assigned to either OKL or single-vision spectacles (SVS). Study duration was 18 months. Outcome measures were axial length (AL) measured with Lenstar LS900 (Haag-Streit, Koeniz, Switzerland) and adverse events graded with Efron Grading Scale for Contact Lens Complications.

Results: Nineteen participants completed the 18-month follow-up in the OKL group and 28 in the SVS group. The average AL elongation in the OKL group was 0.24 mm smaller as compared to the SVS group (95% confidence interval 0.12-0.36, mixed model adjusted for baseline sex, age and AL). There were no fast progressors (>0.75 D/year) in the OKL group during the follow-up period in contrast to 22% in the SVS group. No treatment-requiring or vision-threatening adverse events were observed.

Conclusion: Orthokeratology lenses reduced AL elongation in myopic Scandinavian children by 59%, with no treatment-requiring or vision-threatening adverse events. The results align with outcomes of previous clinical trials.

Keywords: dropout; myopia; myopia control; orthokeratology lenses; progression rate; randomized; safety.

Fig. 1

Overview of visits and examinations from baseline to 18‐month follow‐up in a randomized trial on myopic, Danish children using either orthokeratology lenses or single‐vision spectacles. Examinations: *Ocular health by slit‐lamp examination, topography, non‐cycloplegic subjective refraction and visual acuity. ^#Axial length, cycloplegic autorefraction. ^€New spectacles were provided for all subjects if a change (≥0.25 D SER) had occurred since prior examination. ^&Orthokeratology lenses were replaced every 12 months followed by a day 7 lens check with examinations as indicated by ^*.

Fig. 2

Adjusted predictions with 95% confidence intervals of axial length at follow‐up visits 6 to 18 months. The adjusted predictions are based on a mixed model with axial length at 6‐, 12‐ and 18‐month follow‐up. M06 = 6‐month follow‐up; M12 = 12‐month follow‐up; M18 = 18‐month follow‐up; OKL = orthokeratology group; SVS = single‐vision spectacle group.

Fig. 3

Progression status at 18‐month follow‐up for the orthokeratology and single‐vision spectacle groups. No progression: ≤0 mm; emmetropic progression (0 D/year): >0–0.22 mm; low progression (<0.5 D/year): >0.22‐0.41 mm; intermediate progression (>0.5 < 0.75D/year): >0.41‐0.62 mm; fast progression (>0.75D/year): >0.62 mm. M18 = 18‐month follow‐up; OKL = orthokeratology group; SVS = single‐vision spectacle group.