Science Snippets: Orthokeratology

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How common is Microbial Keratitis in Children wearing Orthokeratology?

This study estimated the incidence of microbial keratitis (MK) in children wearing overnight orthokeratology lenses in a group practice in Russia. The study observed a rate of MK of approximately 5 cases per 10,000 patient years, which is lower than previous reports from clinical data gathered over a decade ago, and similar to that associated with daily-wear soft contact lenses. This should give both practitioners and parents confidence in considering overnight orthokeratology as a means of myopia control. The mean age of MK was 15.2±1.1 versus the mean age of fitting 12 years, indicating children are more likely to experience MK years after being fitted, rather than in the first few months. This highlights the importance of remaining vigilant in educating patients on good hygiene and lens care for the duration of their treatment period. The finding of a higher safety profile compared to previous reports could be due to the data being gathered from a single group of practices with standardized training and care protocols, and/or reflecting a concerted effort to improve OK safety and compliance in the past decade or so.

Bullimore M, Mirsayafov D, Khurai A, et al. Pediatric Microbial Keratitis With Overnight Orthokeratology in Russia. Eye & Contact Lens. 2021;47(7):420-425. [Link]

Which works best - atropine 0.02% or orthokeratology?

This paper compared the efficacy of 0.02% atropine eye drops and orthokeratology (OK) in controlling axial length (AL) elongation in a group of 203 Chinese children aged 7-14. The 0.02% atropine drops were diluted from 1% and these children wore single vision spectacles, whilst the orthokeratology group was historical. Following 2 years of treatment, the atropine group demonstrated significantly faster axial length elongation (0.58±0.35mm) compared to the OK group (0.36±0.30mm). In both groups, younger age and shorter baseline axial length were associated with faster axial length elongation, as expected. Whilst the ages of the two groups matched, the OK group had a longer baseline AL, so this could account to some degree for the slower overall progression observed. Every 1mm shorter baseline axial length resulted in 0.11mm faster AL elongation in the OK group and 0.17mm in the 0.02% atropine group over two years. With overlapping 95% confidence intervals, the overall effect between the two groups could be similar; although when AL was controlled for, a stronger myopia control effect was found in higher myopes wearing OK, but not in the 0.02% atropine group.  Clinically, this study indicates that OK may be more effective in controlling AL elongation in comparison to 0.02% atropine, particularly in children with higher baseline myopia, but further research is required as the two groups weren’t completely matched.

Lyu Y, Ji N, Fu AC, et al. Comparison of Administration of 0.02% Atropine and Orthokeratology for Myopia Control. Eye Contact Lens. 2021 Feb 1;47(2):81-85. [Link]

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About Kate

Dr Kate Gifford is a clinical optometrist, researcher, peer educator and professional leader from Brisbane, Australia, and a co-founder of Myopia Profile.

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About Ailsa

Ailsa Lane is a contact lens optician based in Kent, England. She is currently completing her Advanced Diploma In Contact Lens Practice with Honours, which has ignited her interest and skills in understanding scientific research and finding its translations to clinical practice.

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About Clare

Clare Maher is a clinical optometrist in Sydney, Australia, and a second year Doctor of Medicine student, with a keen interest in research analysis and scientific writing.

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