Orthokeratology Lens Diameter and Age May Determine Axial Growth Rate

A longer orthokeratology lens diameter and older patient age may be associated with a slower axial growth rate among children with myopia during a 4-year period, according to a study published in Eye & Contact Lens.

Researchers retrospectively reviewed data from 84 children with myopia (average age at baseline, 10.76 years; girls, 45) who were fit with orthokeratology lenses at a single center between November 2015 and March 2018. Study participants underwent axial length measurements every year during a 4-year period, and investigators compared axial growth rates at each visit.

There was a significant difference in axial length growth rate (P <.001) at each follow-up visit, according to the report. Slower axial growth rate was associated with longer baseline axial length (P =.045), more myopic spherical equivalent refraction (SER; P =.003), and longer orthokeratology lens diameter (P =.037). Axial growth rate was not affected by sex, pupil diameter, flattest keratometry (K1), or astigmatism.

After baseline age was included in the analysis, baseline axial length and SER became statistically insignificant, but orthokeratology lens diameter continued to remain significantly correlated with axial growth rate (P <.001).

Since baseline age demonstrated the strongest correlation with axial growth rate, the team compared growth rates among participants stratified according to age. Individuals aged 9 years showed faster axial growth compared with children aged 11 years or older. Participants aged 10 to 11 years experienced faster axial growth compared with children aged 13 to 16 years, but there was no significant difference between children aged 13 to 17 years.

Despite this more rapid axial growth among children with younger age, the researchers assert, “for children with early-onset myopia, early use of orthokeratology lenses can make them obtain the most benefits and delay the progress of myopia so as to reduce the prevalence of high myopia.”

Study limitations include the lack of a control group, the use of 3 different orthokeratology lens designs, and failure to consider anterior chamber depth, central corneal thickness, age of myopia onset, corneal power, and parental refraction as variables affecting axial growth rate.