Effects of Myopic Orthokeratology on Visual Performance and Optical Quality

Abstract

Objectives: To analyze the changes in visual performance and optical quality after orthokeratology (ortho-k) treatment and its correlation with the magnitude of lens decentration and the diameter of treatment zone (TxZ). Methods: A prospective study was conducted in 27 eyes of 27 patients wearing ortho-k contact lens. Area under log contrast sensitivity function (AULCSF), modulation transfer function cutoff values (MTF cutoff ), Strehl ratio (SR), and objective scattering index (OSI) were measured and compared before and 1 month after ortho-k lens treatment. Refractive sphere, astigmatism, and diameter and decentration of TxZ were tested against the change in AULCSF, MTF cutoff , SR, and OSI after ortho-k treatment in stepwise multiple linear regression models. Results: Objective scattering index significantly increased and AULCSF, MTF cutoff , and SR significantly decreased after ortho-k lens wear (all P <0.001). The mean TxZ diameter was 3.61±0.26 mm, and the mean magnitude of TxZ decentration was 0.60±0.16 mm. The amount of lens decentration significantly correlated with the change in AULCSF and MTF cutoff ( P =0.027 and P =0.005, respectively). The diameter of TxZ significantly correlated with the change in MTF cutoff and SR ( P =0.005 and P =0.024, respectively). Conclusions: Visual and optical quality decreases after ortho-k treatment, which can be alleviated by a larger TxZ diameter and a smaller lens decentration.