The prevalence of myopia is increasing throughout the world, even in countries that weren’t affected much years ago—including the Scandinavian population, which has seen a reported increase from 13% to 25%.
Several studies have investigated the effects of different treatments on reducing the myopia progression, with orthokeratology lenses showing the most promising results. So, for this study, researchers decided to dive further and investigate the efficacy of myopia control defined by axial length (AL) elongation and the safety of orthokeratology.
Sixty Danish children ages six to 12 years with myopia ranging from 0.5D to 4.75D spherical component and refractive astigmatism ≤2.5 D in both eyes were randomly assigned to either ortho-K or single-vision spectacles as a control group.
Nineteen participants completed the 18-month follow-up in the ortho-K group and 28 in the control group. The average AL elongation in the study group was 0.24mm smaller compared to the SVS group. There were no fast progressors in the study group during the follow-up period in contrast to 22% in the controls. No treatment-requiring or vision-threatening adverse events were observed.
Overall, ortho-K reduced axial elongation in myopic Scandinavian children by 59%, with no treatment-requiring or vision-threatening adverse events.
The study showed lenses treatment efficacy varies. “Surprisingly, we found that about 50% of subjects in the ortho-K group had an axial growth less or equivalent to emmetropic axial growth,” the authors explained in their study. “In addition, no fast progressors existed in the ortho-K group. This aligns with the hypothesis that treatment with orthokeratology may reduce axial growth in all subjects and thus limit the number of progressors.”
Authors attribute the large dropout due children being more tired and less motivated for the orthokeratology handling at bedtime during the dark season. Previous studies have revealed similar high dropout rates, “which highlights the need to make different treatment modalities available for the control of myopia,” authors noted in their study.
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). Acta Ophthalmol. Epub ahead of print.