First Author: S.Hoshi JAPAN
Co Author(s): T. Hiraoka Y. Sato T. Oshika
Purpose:
This 3-year prospective study was conducted to assess efficacy and safety of long-term application of overnight orthokeratology for young myopes.
Setting:
Fifty-seven eyes of 57 patients (38 males, 19 females; age 7 to 19; mean ± SD, 11.3 ± 3.1) who visited Sato Yuya Eye Clinic from March 2002 to November 2009 were enrolled in the study. Orthokeratology lenses with four-zone reverse-geometry design were used in the study. The patients were instructed to wear their orthokeratology lenses every night for at least 7 consecutive hours for 3 years.
Methods:
Uncorrected visual acuity and refraction were measured before and 1, 6, 12, 24, 36 months after orthokeratology lens wear started. Corneal endothelial cell density and axial length were evaluated before and 12, 24, 36 months after orthokeratology lens wear started. Unpaired t test and x2 test were used to compare the baseline data between the subjects who completed the study and the subjects who dropped out of the study. Time course of changes in uncorrected visual acuity, spherical equivalent refractive error (SER), astigmatism, corneal endothelial cell density, and axial length were assessed by repeated-measures analysis of variance (ANOVA). Where appropriate, Dunnett corrections were used to take account of post-hoc comparisons. Differences were considered statistically significant at p < 0.05.
Results:
Among the 57 patients, 51 patients successfully completed the 3-year follow-up examination (33 males, 18 females; age 7 to 18; 10.9 ± 2.7). Six patients uncompleted the study (5 males, 1 female; age 7 to 19; 14.3 ± 4.5), giving a dropout rate of 10.5%. There were significant differences in baseline age (p = 0.009) and SER (p = 0.025) between the subjects who completed and who dropped out of the study. No severe complications were noted throughout the observation period. There were significant improvements in uncorrected visual acuity (p < 0.001) and in SER (p < 0.001), the post-hoc test showed that compared to the baseline values both factors were significantly improved at all subsequent visits (p < 0.001). There was no significant change in astigmatism (p = 0.382) and corneal endothelial cell density (p = 0.131) throughout the observation period. In 3 years, axial length increased from 24.52 ± 0.80 to 25.03 ± 0.83 mm. The increases in axial length for 3 years was 0.51 ± 0.39 mm. Axial length significantly increased with time (p < 0.001), the post-hoc test showed that compared to the baseline value axial length elongated at all subsequent visits (p < 0.001).
Conclusions:
The dropout rate of this study (10.5%) was similar to that of other overnight orthokeratology studies in children. Myopic refractive error in dropouts was significantly larger than that in subjects who completed the 3-year study, indicating that subjects with higher myopia are more vulnerable to dropout from overnight orthokeratogy treatment. Uncorrected visual acuity and SER sufficiently improved at 1-month visit, and thereafter maintained that level over the study period. Besides, we did not observe any severe adverse events or statistically significant corneal endothelial cell loss during the 3-year observation period. The present study demonstrated clinically acceptable efficacy and safety of long-term application of overnight orthokeratology for mild to moderate myopia in Japanese children. FINANCIAL DISCLOSURE?: No
Please wait while information is loading.
