After evaluating refractive and corneal responses in myopic children wearing orthokeratology lenses, researchers recently found that increasing the compression factor did not affect the first-fit success rate or the external ocular health—but it did correct refractive error more quickly.

This double-blind, self-controlled study randomly fit 25 participants around the age of nine or 10 with what the researchers deemed ‘conventional compression factor’ (CCF, 0.75D) in one eye and ‘increased compression factor’ (ICF, 1.75D) in the other. The team evaluated refraction, visual acuity (VA), external ocular health and corneal response on a weekly basis during one month of use and after discontinuation of lens wear until achieving stabilization.

The investigators found the first-fit success rates for conventional compression and increased compression were 93% and 96%, respectively. They noted that myopia, unaided VA, central corneal thickness, anterior corneal curvatures, apical power and corneal resistance factor all changed significantly during the study period, but the only significant inter-eye difference was for myopia reduction. Their results indicate that myopia, anterior corneal curvatures and apical power were significantly different compared with baseline at the end of the washout period of three weeks. Also, attempted target was achieved in 80% of conventional compression eyes and 60% of increased compression eyes by the end of the next week.

While the results are promising, the researchers note further investigation should focus on the long-term effects of increased compression factor on myopia control compared with conventional treatment. 

Wan K, Lau JK, Cheung SW, et al. Refractive and corneal responses of young myopia children to short-term orthokeratology treatment with different compression factors. Cont Lens Ant Eye. November 5, 2019. [Epub ahead of print].