Orthokeratology with increased compression factor (OKIC): study design and preliminary results

Kin Wan, Jason Ki-kit Lau, Sin Wan Cheung, Pauline Cho

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Objective To present the study design and the baseline data of a prospective cohort study investigating the safety, refractive correction and effectiveness of myopia control in subjects fitted with orthokeratology (ortho-k) lenses of different compression factors.Methods and analysis This study is a 2-year longitudinal, double-masked, partially randomised study. Myopic children aged between 6 and 10 years are recruited and they may choose to participate in either the ortho-k or spectacle-wearing group. Subjects in the ortho-k group are randomly assigned to wear ortho-k lenses of either conventional compression factor (CCF, 0.75 D) or increased compression factor (ICF, 1.75 D). For the ortho-k subjects, the time and between-group effects within the first month of lens wear were analysed.Results Sixty-nine ortho-k subjects (CCF: 34; ICF: 35) and 30 control subjects were recruited. There were no significant differences in baseline demographic data among the three groups of subjects (pgt;0.19). At the 1-month visit, the first fit success rates were 9700k group, respectively. A higher percentage of ICF subjects could achieve full correction (CCF: 88.2 ICF: 94.3. The change in axial length was significantly higher in the ICF group (CCF, 0.003 mm; ICF, -0.031 mm) (plt;0.05). No significant between-group differences in daytime vision or in the coverage and depth of corneal staining between the two ortho-k groups (pgt;0.05) were observed at any visit.Conclusion ICF did not compromise the corneal integrity and the lens centration within the first month of lens wear. The preliminary performance of ortho-k lenses with ICF of 1.00D shows that it was safe to be used in the longer term for the investigation of myopia control.Trial registration number NCT02643342.
Original languageEnglish
Article numbere000345
JournalBMJ Open Ophthalmology
Issue number1
Publication statusPublished - 4 May 2020

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