June 2022
Volume 63, Issue 7
Open Access
ARVO Annual Meeting Abstract  |   June 2022
Myopia control effect of small back optic zone diameter orthokeratology lenses over two years
Author Affiliations & Notes
  • Biyue Guo
    School of Optometry, The Hong Kong Polytechnic University, Hung Hum, Kowloon, Hong Kong
  • Sin Wan Cheung
    School of Optometry, The Hong Kong Polytechnic University, Hung Hum, Kowloon, Hong Kong
  • Randy Kojima
    Pacific University, Forest Grove, Oregon, United States
  • Pauline Cho
    School of Optometry, The Hong Kong Polytechnic University, Hung Hum, Kowloon, Hong Kong
  • Footnotes
    Commercial Relationships   Biyue Guo None; Sin Wan Cheung None; Randy Kojima Medmont International Pty., Code C (Consultant/Contractor), Precision Technology Services Ltd., Code I (Personal Financial Interest), KATT Design Group, Code I (Personal Financial Interest); Pauline Cho None
  • Footnotes
    Support  Research Residency Scheme of the School of Optometry from The Hong Kong Polytechnic University to B. Guo
Investigative Ophthalmology & Visual Science June 2022, Vol.63, 1464. doi:
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    • Get Citation

      Biyue Guo, Sin Wan Cheung, Randy Kojima, Pauline Cho; Myopia control effect of small back optic zone diameter orthokeratology lenses over two years. Invest. Ophthalmol. Vis. Sci. 2022;63(7):1464.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : To investigate the axial elongation (AE) in children wearing orthokeratology (ortho-k) lenses with different back optic zone diameters (BOZD).

Methods : Seventy Chinese children aged 6 to <11 years, with myopia between -4.00 to -0.75 D and astigmatism ≥ -2.50 D, were randomly assigned to use ortho-k lenses with 6mm (6-MM group) and 5mm (5-MM group) BOZD for two years. Corneal topography, sub-foveal choroidal thickness (ChT), and axial length were measured at baseline and 6-monthly visits. Treatment zone (TZ) was defined as the central area of corneal flattening bordered by the circumferential ring, where no dioptric change on the tangential subtractive map (difference between the pre- and the post- treatment) was observed. The horizontal and vertical TZ sizes were determined with the aid of a customized computer software. Linear mixed models were used to investigate factors (TZ sizes and changes of ChT) that may affect AE, considering baseline parameters (sex, age, pupil size, refraction, axial length and visual acuity).

Results : Data of the right eye of 45 subjects (23 in 6-MM and 22 in 5-MM group) who completed the study were analysed. At the 24-month visit, AE and TZ size were significantly reduced in the 5-MM group (AE: 0.15 ± 0.21 mm; horizontal/vertical TZ size: 2.69 ± 0.28/2.65 ± 0.22 mm) compared to the 6-MM group (AE: 0.35 ± 0.23 mm; horizontal/vertical TZ size: 3.84 ± 0.39/3.42 ± 0.34 mm) (p = 0.005; p < 0.001, respectively). ChT was not significantly changed after 24 months of lens wear in both groups (p > 0.05). Linear mixed models showed that the horizontal and vertical TZ sizes (β = 0.130, p = 0.001; β = 0.136, p = 0.003, respectively) and changes in ChT (β = -0.002, p < 0.001) were significantly associated with AE, controlling for the baseline parameters.

Conclusions : The 5-MM group exhibited a smaller TZ size which was associated with smaller AE. The findings also suggested that changes in ChT, although weak, may play a role in regulating myopia progression.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

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