Effects of Relative Corneal Refractive Power Changes on Relative Peripheral Refraction After Orthokeratology

This study investigated the relationship between changes in summed relative corneal refractive power (CRP) and changes in relative peripheral refraction (RPR) in the retina of myopic children undergoing orthokeratology.

A prospective self-controlled study was conducted involving myopic children aged 8 to 12 years who were fitted with four-zone reverse-geometry orthokeratology lenses for 3 months. Corneal topography and peripheral refraction were measured at baseline, 1-, and 3-month follow-up visits. Changes in the summed relative CRP within the 4-, 5-, and 6-mm zones centered on the corneal geometrical center and ΔRPR across the annular regions and quadrants were derived. Partial correlation and multiple regression models were used to examine the relationship between changes in summed relative CRP and the changes of RPR.

Seventy-eight of 85 participants completed the study. After adjusting for baseline spherical equivalent and treatment zone decentration, statistical correlations were found between changes in summed relative CRP within the central 5-mm zone and changes in RPR (ΔRPR) in specific regions (r=-0.24 to 0.45). Multiple regression analysis identified ΔSum5N (defined as changes in summed relative CRP in the nasal quadrant within a 5-mm diameter circular area centered at the corneal geometric center) as the strongest predictor of ΔRPR-T (defined as the ΔRPR in the temporal region of the peripheral retina) (adjusted R2=0.50), with each 1.0 D increase in ΔSum5N corresponding to a 0.179 D decrease in ΔRPR-T.

Changes in summed relative CRP may help predict ΔRPR after orthokeratology. Regional increases, especially in the nasal and inferior cornea, are linked to larger myopic shifts in peripheral defocus, especially on the temporal side. Further investigation is required to establish robust association.