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Orthokeratology lenses with increased compression factor (OKIC): A 2-year longitudinal clinical trial for myopia control

  • Author Footnotes
    1 Jason K. Lau and Kin Wan contributed equally.
    Jason K. Lau
    Footnotes
    1 Jason K. Lau and Kin Wan contributed equally.
    Affiliations
    Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Hong Kong SAR, China
    Search for articles by this author
  • Author Footnotes
    1 Jason K. Lau and Kin Wan contributed equally.
    Kin Wan
    Correspondence
    Corresponding author.
    Footnotes
    1 Jason K. Lau and Kin Wan contributed equally.
    Affiliations
    Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Hong Kong SAR, China
    Search for articles by this author
  • Pauline Cho
    Affiliations
    Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Hong Kong SAR, China
    Search for articles by this author
  • Author Footnotes
    1 Jason K. Lau and Kin Wan contributed equally.
Published:August 19, 2022DOI:https://doi.org/10.1016/j.clae.2022.101745

      Abstract

      Purpose

      To investigate the effectiveness of orthokeratology (ortho-k) lenses and corneal changes with increased compression factor for myopia control over a 2-year period.

      Methods

      Young participants (age: 6–<12 years), with low myopia (0.50–4.00 D) and low astigmatism (≤1.25 D), were recruited and allowed to choose to wear either single-vision spectacles or ortho-k lenses (randomly assigned to compression factor of either 0.75 or 1.75 D). Axial length and cycloplegic refraction were measured at six monthly intervals for two years by a masked examiner. The myopia control effectiveness was determined by axial elongation.

      Results

      A significant number of control (63 %) dropped out, mainly due to concern about myopia progression (58 %). A total of 75 participants (mean age: 9.3 ± 1.0 years; control: n = 11, ortho-k [0.75 D]: n = 29, ortho-k [1.75 D]: n = 35) completed the study. Considering ortho-k groups only, the mean axial elongation of participants wearing ortho-k lenses of conventional compression factor (0.75 D) and increased compression factor (1.75 D) were 0.53 ± 0.29 and 0.35 ± 0.29 mm, respectively, over the 2-year study period. The between-group differences in corneal health were not significant at all visits.

      Conclusion

      Participants wearing ortho-k lenses of increased compression factor further slowed axial elongation by 34%, when compared with the conventional compression factor without compromising corneal health. Further investigations are warranted to confirm the potential mechanism of an increased compression factor for improved myopia control effectiveness.

      Keywords

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