For myopic patients treated with orthokeratology (ortho-K), a shift in their corneal power early in treatment may be a good predictor of their long-term axial length, a study in the British Journal of Ophthalmology reports.

Since ortho-K’s success in myopia control varies among individuals, a team of Chinese researchers investigated whether the variation was linked to an “areal summed corneal power shift” in myopic children—a novel parameter derived from topographic measurements and defined as the summed refractive change at the follow-up visit from baseline. The researchers sought to understand whether early changes in the cornea could be linked to the long-term success of treatment.

The prospective study enrolled 130 myopic children between the ages of eight and 15 who were treated with ortho-K lenses. The researchers measured corneal topography and axial length at baseline and then at one, three, six, nine and 12 months after ortho-K lens wear.

The children’s collective spherical equivalent at baseline was approximately -3.00D. The researchers reported the areal summed corneal power shift was 6.90±6.09D*mm at the one-month visit and remained stable throughout the follow-up period. Most important, the study found patients with a greater areal summed corneal power shift at one month generally had a slower axial length elongation at the 12-month visit.

The parameter has the potential to be a marker on whether axial growth is slowed down in myopic children, the researchers concluded.