Abstract
Purpose :
Orth-K lens wear is an effective method for controlling myopia progression in schoolchildren, and its effect is biometrically measured in clinical practice.To test stability of the biometrical measurement,this study was designed to test refraction and biometry changes for children after taking the Ortho-K lens off over two days.
Methods :
Eighteen children aged 8 to 13 years old(mean age=10.61±1.46), with myopia -0.75 to -5.25DS(mean sphereical equivalent SE=2.78±1.23) and astigmatism≤1.00DC,were fitted with Ortho-K lens. Refraction and curvature of the right eye were measured with an auto-refractor(KR-1,Topcon), Corneal Tomography(Oculus Pentacam@) and IOL Master(V5.5,carl Zeiss) were used to measure central corneal chickness(CCT),anterior chamber depth(ACD)and axial length(AL). The first test was performed at 9:00am of the morning of day one after taking the Ortho-K lens about two hours. Following up tests were taken at 12:00am and 5:00pm of the day one and 9:00am,12:00am and 5:00pm of the day two, respectively.
Results :
For all children,the mean SE was changed from-1.27±0.95D at the first test to 0.29±0.04,0.05±0.35,-0.97±1.18,-0.86±1.17,-0.74±1.04D at the follow-up tests respectively, and all SE values at the day two were significantly increased(p＜0.05).No significant change in mean biometrical measurements was found. But,when difference of the follow-up tests from the first test was tested, significant increases in ACD were found in the last four tests(0.024±0.038,0.044±0.05,0.046±0.047,0.062±0.054mm respectively).The difference of CCT were also significantly for all follow-up tests except of 9:00am of day two. The differences of AL were -0.007±0.034,-0.003±0.014,0.007±0.009,0.013±0.013,-0.001±0.013mm respectively at the five follow-up tests as compared to the first test, and the fourth and fifth measurements were significantly different(p＜0.05). The changes in SE in the follow-up tests were positively correlated to baseline refraction, but no significant correlation was found for the AL.
Conclusions :
After taking Ortho-K lens off, refractive error gradually returns and the amount of myopia returning is associated with the baseline refractive error. Axial length is stable over two-days after lens off, and its measurement is reliable for evaluating Ortho-K effect on myopia progression in schoolchildren.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.