Relationship between contrast sensitivity and corneal shape following overnight orthokeratology.

Aim: To evaluate the relationship between contrast sensitivity (CS) and corneal shape following overnight orthokeratology (OK).

Methods: We conducted a retrospective clinical study of 80 lens-wearing myopia patients, all of whom had undergone OK and had been evaluated by Orbscan II topography. We measured the surface irregularity index (SIRI) of corneal topography at 3 and 5 mm, the size of the flattened central corneal curvature of OK lens (zone A), the size of the cornea altered by OK lens (zone B), the size of the pupillary area at the corneal level (zone C), the area of crossover between zones A and C (zone AC), the area of crossover between zones B and C (BC), the ratio of BC to B (BC/B), and the ratio of AC to C (AC/C).