Overnight Orthokeratology: A Preliminary Report

Abstract

Purpose: To evaluate the safety and efficacy of overnight orthokeratology on unaided visual acuity, manifest myopia, and myopic control. Methods: 30 patients with myopia and a mean age of 12.5 years were enrolled. After a comprehensive eye examination, patients were fitted with reverse-geometry rigid gas permeable lens (Contex-D or Contex-E). Unaided visual acuity, manifest refractive error, and the biomicroscopic data were collected at the baseline and 1-day, 1-week, 1- month, 3-month and 6-month after treatment separately. The axial length was also measured before and after 6-month follow-up. The improvement in unaided visual acuity, the amount and percentage of the manifest refractive error change, and the change in axial length were evaluated. The safety of overnight orthokeratology was also determined at each examination day by slit lamp and topography. Results: Of the 30 subjects enrolled, 25 completed the 6-month follow-up. In these 25 right eyes, the mean change in spherical equivalent (SE) of manitest refraction from the baseline to 1-day, 1-week, 1-month, 3-month and 6-month visit was 1.51±0.860, 2.70±1.06D, 3.18±1.31D, 3.38±1.37D, 3.46±1.40D, respectively. The percentage change of SE was 39.42% (1-day), 70.50% (1-week), 83.03% (1-month), 88.25% (3-month), 90.34% (6-month). The percentage changes of SE in the low-myopia group (under 4.OD) were faster than those in the moderate-myopia group (over 4.OD) in the first month, but were similar after one month. The mean axial length was 24.83mm before treatment and 24.89mm after six months of treatment. No corneal ulcer or infiltration was found during the follow up period. Conclusion: Overnight orthokeratology was effective in improving unaided visual acuity and reducing manifest myopia. Further long-term study is needed to confirm its safety and efficacy.