Topographic corneal epithelial thickness map before and after orthokeratology.

The corneal epithelium thinned from the center to the paracenter, and the mid-peripheral epithelium thickened. There was more thinning of the temporal and inferior zones compared with the nasal and superior zones of the paracenter, with further thickening in the nasal zone compared with the temporal zone in the mid-periphery. *P<0.05, **P<0.01, and ***P<0.001.