Orthokeratology (ortho-k) lenses with increased compression factor slow axial length elongation by 34% compared with lenses with conventional compression factor and are not a threat to corneal health, according to a study published in Contact Lens and Anterior Eye.
Researchers included 75 children (mean age, 9.3±1.0 years) in a prospective, controlled clinical trial. Participants chose to receive treatment with either spectacle lenses (n=11) or ortho-k. Children opting for ortho-k were randomly assigned to lenses with conventional compression factor (0.75 diopters [D]; n=29) or lenses with increased compression factor (1.75D; n=35). Patients underwent cycloplegic refraction, corneal topography, and axial length measurement at baseline and every 6 months for a period of 2 years.
Among participants treated with ortho-k, axial length increased by 0.53±0.29 mm and 0.35±0.29 mm in the conventional and increased compression factor groups, respectively, over the 2-year study duration. Overall, children treated with the increased compression factor lenses progressed at a 34% slower rate than children treated with conventional progression factor lenses, and differences in axial elongation between the 2 groups were significant at all visits (P =.018). Mild corneal staining was observed in both ortho-k groups (no more than grade 2 corneal staining for depth and coverage) with no significant differences noted between the 2 groups at any visit.
A significant number of control individuals dropped out due to concerns over progressing myopia (63%). Among individuals treated with spectacle lenses, myopia progressed from -2.41±0.83 to -3.27±1.06 D and axial length increased from 24.83±0.81 to 25.40±0.99 (P <.001 for both).
“[I]ncreasing the compression factor of ortho-k lenses by 1.00 D improved myopia control effectiveness by approximately 34 % over two years,” according to the researchers. “Increased compression factor did not induce significantly more corneal staining when compared with conventional compression factor.”
Study limitations include a lack of randomization to treatment methods and the exclusion of participants who were not of Chinese ethnicity.
Disclosure: This research was supported by Menicon Co. Ltd. Please see the original reference for a full list of disclosures.
Lau JK, Wan K, Cho P. Orthokeratology lenses with increased compression factor (OKIC): a 2-year longitudinal clinical trial for myopia control. Cont Lens Anterior Eye. Published online August 19, 2022. doi:10.1016/j.clae.2022.101745