Aspheric orthokeratology lenses demonstrate better myopia slowing efficacy in children with myopia compared with orthokeratology lenses with a spherical base curve, according to research published in Ophthalmic and Physiological Optics. This style of lens allows less axial elongation and greater absolute relative peripheral refraction changes compared with spherical lenses, the report shows.
Researchers conducted a prospective, randomized, controlled, single-masked trial to compare axial elongation and relative peripheral refraction changes in children with myopia wearing either spherical or aspheric orthokeratology lenses. The team randomly assigned study participants to treatment with aspheric (n=31; mean age, 9.68 years; 55% boys) or spherical orthokeratology lenses (n=32; mean age, 9.57 years; 26% boys) and assessed peripheral refraction at 10°, 20°, and 30° along the temporal and nasal retina at baseline and during a 12-month follow-up visit. The investigators also measured axial length with cycloplegia at baseline and at 6- and 12-month visits. Only data for the right eye was included in the analysis.
At baseline, the investigators observed no significant differences between groups for axial length or relative peripheral refraction. At 12 months, however, they determined that aspheric orthokeratology lenses produced a greater absolute relative peripheral refraction change along the horizontal meridian compared with spherical lenses (P <.001). The researchers also found that axial elongation was slower among participants treated with the aspheric orthokeratology lenses compared with individuals undergoing treatment with spherical lenses at 1 year (0.19 vs 0.29 mm; P=.03).
Axial elongation demonstrated a correlation with relative peripheral refraction changes at 10° and 20° along the peripheral retina in individuals treated with aspheric orthokeratology lenses (P =.02 and P =.03, respectively), but this correlation was not observed among individuals treated with spherical lenses, according to the report.
“[T]reatment with [aspheric base curve] ortho-k lenses showed a higher absolute [relative peripheral refraction change] at the 12-month visit and less axial elongation at the 6- and 12-month visits compared with treatment with a [spherical base curve] ortho-k lens,” according to the study authors. “This suggests that the use of an ortho-k lens with an [aspheric base curve] is more effective in increasing the efficacy of myopia control in children than an ortho-k lens with a [spherical base curve].”
Study limitations include the lack of a single vision spectacle group as a control, the single-masked design, a lack of fluorescein pattern assessment and comparison between the groups, and an ethnically homogenous cohort, which may limit globalization of the study’s findings.
Liu T, Chen C, Ma W, Yang B, Wang X, Liu L. One-year results for myopia control with aspheric base curve orthokeratology lenses: a prospective randomised clinical trial. Ophthalmic Physiol Opt. Published online August 16, 2023. doi:10.1111/opo.13213