Purpose.: Our prospective study was conducted to compare axial length elongation in myopic children receiving long-term overnight orthokeratology (OK) treatment to those wearing spectacles as controls. Methods.: There were 59 subjects enrolled in this study. The OK group comprised 29 subjects who matched the inclusion criteria for OK. The control group comprised 30 subjects who also matched the inclusion criteria for OK, but preferred spectacles for myopia correction. Axial length was measured periodically for 5 years using an IOLMaster device, and the time course of changes was evaluated and compared between the groups. Results.: A total of 43 subjects (22 and 21 in the OK and control groups, respectively) completed the 5-year follow-up examinations. At baseline, the mean age ± SD was 10.04 ± 1.43 and 9.95 ± 1.59 years, the spherical equivalent refractive error was −1.89 ± 0.82 and −1.83 ± 1.06 diopters (D), and the axial length was 24.09 ± 0.77 and 24.22 ± 0.71 mm in the OK and control groups, respectively, with no significant differences between the groups. The increase in axial length during the 5-year study period was 0.99 ± 0.47 and 1.41 ± 0.68 mm for the OK and control groups, respectively, and the difference was statistically significant (P = 0.0236, unpaired t-test). The annual increases in axial length were significantly different between the groups for the first (P = 0.0002), second (P = 0.0476), and third years (P = 0.0385), but not for the fourth (P = 0.0938) and fifth (P = 0.8633) years. There were no severe complications throughout the study period. Conclusions.: The current 5-year follow-up study indicated that OK can suppress axial length elongation in childhood myopia.

A number of studies regarding the effect of orthokeratology (OK) on myopia progression have been published and shown that it can slow myopia progression in school-aged children. Recently, OK has been considered to be one of the most effective optical treatments for myopia control. This article reviewed the peer-reviewed literature on the efficacy of OK for myopia control. Although it cannot halt myopia progression completely, the inhibitory effect on axial elongation for 2 years has been reported to be from 32% to 63%, as compared with single-vision spectacles and contact lenses. In addition, the efficacy and acceptable safety have been confirmed even in several long-term studies up to 10 years. However, the possibility of a rebound phenomenon in myopia progression after OK discontinuation remains unknown. It is also unclear how long the treatment should be continued to attain the maximum benefit in each patient. In the near future, further research including assessment of rebound phenomenon should be conducted with longer follow-up periods in more diverse populations.

Purpose. To evaluate relationships among contrast sensitivity function, ocular higher-order aberration, and myopic correction in eyes undergoing overnight orthokeratology for myopia. methods. A prospective study was conducted in 46 eyes of 23 patients undergoing orthokeratology. Inclusion criteria were spherical equivalent refraction between −1.00 and −4.00 diopters (D), refractive astigmatism up to 1.00 D, and best-corrected visual acuity of 20/20 or better. Ocular higher-order aberrations and contrast sensitivity function were determined before and 3 months after initiation of the procedure. We measured three indices of contrast sensitivity function: contrast sensitivity, low-contrast visual acuity, and letter contrast sensitivity with the CSV-1000 charts (Vector Vision Co., Greenville, OH). Area under the log contrast sensitivity function (AULCSF) was calculated from the contrast sensitivity data. results. Orthokeratology significantly improved logMAR uncorrected visual acuity (P < 0.0001; paired t-test) but significantly increased ocular higher-order aberrations (P < 0.0001) and decreased contrast sensitivity function, including AULCSF (P < 0.0001), low-contrast visual acuity (P = 0.0025), and letter contrast sensitivity (P < 0.0001; Wilcoxon signed-rank test). The induced changes in AULCSF, low-contrast visual acuity, and letter contrast sensitivity by orthokeratology showed significant correlation with changes in third-order (Pearson r = −0.430, P = 0.0026; r = 0.423, P = 0.0031; and Spearman r _s = −0.351, P = 0.0186, respectively), fourth-order (r = −0.418, P = 0.0035; r = 0.425, P = 0.0029; and r _s = −0.566, P = 0.0001, respectively), and total higher-order (r = –0.460, P = 0.0011; r = 0.471, P = 0.0008; and r _s = −0.434, P = 0.0036, respectively) aberrations. The induced changes in contrast sensitivity function and higher-order aberrations significantly correlated with the amount of myopic correction (P < 0.01). conclusions. Orthokeratology significantly increases ocular higher-order aberrations and compromises contrast sensitivity function, depending on the amount of myopic correction.

To quantitatively evaluate the effect of overnight orthokeratology lenses intentionally left decentered after 3 months of wear and assess the influence on clinical outcomes such as ocular higher-order wavefront aberrations and contrast sensitivity function. Department of Ophthalmology, Tsukuba University Hospital, Ibaraki, Japan. This prospective study assessed refraction, visual acuity, corneal topography, wavefront aberration, and contrast sensitivity function before and 3 months after overnight orthokeratology treatment. Decentration of the treatment zone from the center of the entrance pupil was determined using computerized videokeratography (TMS-4) and data-analysis software (MatLab). The relationship between decentration and the clinical parameters was analyzed. The mean age of the 23 patients (46 eyes) was 24.2 years+/-3.3 (SD) and the mean spherical equivalent refraction before treatment, -2.38+/-0.98 diopters. The mean magnitude of decentration (0.85+/-0.51 mm) was statistically significantly correlated with the amount of myopic correction (P<.05), increases in coma-like aberration (P<.01), increases in spherical-like aberration (P<.01), and reductions in contrast sensitivity function (P<.0001). Changes in contrast sensitivity function were also statistically significantly correlated with the amount of myopic correction (P<.05), changes in coma-like aberration (P<.01), and changes in spherical-like aberration (P<.01). Stepwise multiple regression analysis showed that the magnitude of decentration was the only explanatory variable related to contrast sensitivity function (P<.0001). Decentered treatment of orthokeratology resulted in decreased contrast sensitivity after treatment, showing that centration of the procedure is crucial to good outcomes.