Time course of changes in ocular higher-order aberrations and contrast sensitivity after overnight orthokeratology

PURPOSE. To investigate prospectively the time course of changes in ocular higher-order aberration and contrast sensitivity after overnight orthokeratology. METHODS. Data from 34 eyes of 17 patients who completed 1-year follow-up examinations were analyzed. The manifest refraction was -2.17 +/- 0.86 D at baseline. Ocular higher-order aberrations for a 4-mm pupil were measured, and the root-mean-square (RMS) of the third-, fourth-, and total higher-order aberrations were determined. Contrast sensitivity was assessed at four spatial frequencies, and the area under the log contrast sensitivity function (AULCSF) was calculated. These examinations were performed before and 1, 2, 3, 6, and 12 months after commencement of the procedure. RESULTS. The treatment significantly increased third-, fourth-, and total higher-order RMS (all P < 0.0001, paired t-test). Log contrast sensitivity significantly decreased at all four spatial frequencies, and AULCSF was also significantly reduced after the treatment (P < 0.0001). To assess the time course of changes in these parameters, posttreatment data were analyzed by using repeated-measures analysis of variance. There were no significant fluctuations in manifest refraction; uncorrected visual acuity; third-, fourth-, and total higher-order RMS; and AULCSF (all P > 0.05). In addition, there was no significant variance in log contrast sensitivity at each spatial frequency during the 1-year follow-up period (all P > 0.05). CONCLUSIONS. The initial reduction in optical quality of the eye and quality of vision after the procedure is stable during the treatment period of at least 1 year, and the reduction does not worsen further after 1 month. Orthokeratology candidates should be fully informed of these changes.