Seven-year retrospective analysis of the myopic control effect of orthokeratology in children: a pilot study

Abstract

Objectives:To investigate retrospectively the difference in myopia progression, over about 7 years, between two groups of Hong Kong Chinese myopic children who wore overnight orthokeratology lenses or single-vision spectacles. Methods: A total of 238 records of children wearing overnight orthokeratology lenses or single-vision spectacles from Eye'ni optical shop (Hong Kong) between January 1999 and December 2009 were reviewed. Refractive and central corneal curvature data with 6-year or a longer follow-up period of 70 patients were retrieved: 34 children (15 boys and 19 girls, aged 9.2 ± 1.8 years) wore orthokeratology lenses and 36 (20 boys and 16 girls, aged 10.2 ± 2.0 years) wore spectacles. Myopic progression was determined as the change of myopia from the baseline to the final visit. Results: No statistically significant differences (P . 0.05) in age, central flat corneal curvatures, baseline refractive error, or follow-up period were observed between the two groups. Average myopic progression of the overnight orthokeratology contact lens cohort (−0.37 ± 0.49 D) was significantly less (P , 0.001) than of the single-vision spectacle group (−2.06 ± 0.81 D) over about 7 years. Conclusion: Our preliminary 7-year data support the claim that overnight orthokeratology contact lenses may be a feasible clinical method for myopic progression control. Prospective and randomized investigations are warranted to overcome the limitations of this retrospective study. Keywords: myopia, contact lens, orthokeratology, myopia progression IntroductionOrthokeratology contact lenses began to be fitted in the late 1960s. At this time, the technique suffered because only a small amount of myopia was corrected, the time for the correction to occur was long, and the technique was unpredictable. Changes in technology and design have made orthokeratology a predictable means of correcting low to moderate myopia safely, such that the technique is now used as an overnight modality in children. New materials with higher oxygen permeability and reverse geometry contact lens design allow myopic children to wear the contact lenses during sleep to temporarily flatten the central cornea (overnight orthokeratology). An orthokeratology lens flattens the central cornea while it steepens the mid-peripheral cornea. This rearrangement of the shape of the cornea induces peripheral myopic defocus. Several investigations [1][2][3] propose that peripheral myopic defocus may play a vital role in myopic progression; thus overnight orthokeratology is hypothesized to control myopic progression. 2Mok and Chung myopia progression in children. The aim of this pilot report was to investigate the difference in myopia progression, over 7 years, between two groups of myopic children who wore either orthokeratology lenses or single-vision spectacles. A retrospective review may provide preliminary data to justify conducting a prospective and randomized long-term study on the effect of orthokeratology on myopia progression, since no report of the effect of orthokerat...

Human Electroretinal Responses to Grating Patterns and Defocus Changes by Global Flash Multifocal Electroretinogram

“…Subsequent studies have shown that peripheral defocus can influence overall refractive error development in chicks [ 67 ] or in monkeys [ 4 , 68 ], highlighting the dominant role of peripheral retina in the regulation of ocular growth. In addition, myopic progression has been slowed by wearing orthokeratology lenses in clinical studies, and it has been speculated that the presence of myopic defocus on the peripheral retina may be the critical factor in slowing myopia development [ 69 , 70 ]. In this study, IC percentage change in differentiating optical defocus in the peripheral retina can also be noticed in the 0.24cpd condition, but is not observed in the 4.8 cpd condition.…”

Effect of Orthokeratology on myopia progression: twelve-year results of a retrospective cohort study

“…We also acknowledge the retrospective design of this study might carry the potential bias. Moreover, the disparity of case number between high astigmatism and low astigmatism may have made the statistical result unstable [ 41 ]. Besides, the retrospective design of this study might also carry the potential for both practitioner and investigator bias as neither the examiner nor the patient were masked to the treatment groups.…”

“…A five-year prospective study that assessed the efficacy of OK showed a reduced rate of manifest refraction progression in OK-wearing eyes in the first 3 year of treatment [ 40 ]. Two retrospective studies comparing children wearing OK lenses with single-vision spectacles showed a reduced rate of manifest refraction progression in OK-wearing eyes over 7-year and 8-year periods [ 41 , 42 ].…”