Orthokeratology (ortho-k) lenses remodel the retina to be more symmetric and less prolate, according to findings published in Contact Lens and Anterior Eye.
Researchers conducted a prospective study to assess the influence of wearing, and then discontinuing, ortho-K lenses on retinal shape and peripheral refraction in children with myopia. The study consisted of an ortho-k group and a single vision spectacle (SVS) control group, with 58 participants with myopia aged 8-12 years. Ortho-k lenses were used for 12 months and then discontinued for 1 month. Outcome measures included peripheral eye length (PEL), relative peripheral refraction (RPR), and corneal parameters. All were measured in the right eye on the nasal and temporal retinal sides at baseline, 6 months, and 12 months (13 months in ortho-k group).
Eyes in the SVS group were more asymmetric and prolate due to faster elongation of the temporal side PEL. In the ortho-k group, nasal retinal side PEL grew faster, nasal RPR developed less hyperopic defocus, and eye shape became more symmetric and less prolate. The central cornea also became thinner and flatter while the peripheral cornea became steeper. Researchers noted no significant difference in corneal thickness change, relative peripheral corneal power, or K-values for the ortho-k and SVS groups at 12 months.
No differences were observed between the corneas of the 2 groups after the treatment period except for a change in thickness at the central and N10° positions. Corneal toricity increased in both the SVS and ortho-k groups. Participants in the ortho-k group indeed increased corneal toricity but, researchers explain, “it was not different from the SVS group. Therefore it was speculated that the increased toricity was due to the progression of myopia and not the ortho-k lens wear.”
A study limitation is a lack of randomization in determining participant groups.
Huang Y, Li X, Ding C, Chen Y, Chen H, Bao J. Orthokeratology reshapes eyes to be less prolate and more symmetric. Cont Lens Anterior Eye. Published online November 1, 2021. doi:10.1016/j.clae.2021.101532.