Highlights
- •Increasing the compression factor of orthokeratology lenses by 1.00 D leads to faster refractive correction.
- •Increased compression did not affect the ortho-k lens fitting.
- •External ocular health was not compromised by increased compression factor.
- •No significant differences in the corneal biometrics between eyes fitted with different compression factors (0.75 and 1.75 D).
Abstract
Purpose
To evaluate changes in refractive and corneal responses in myopic children wearing
orthokeratology (ortho-k) lenses with conventional compression factor (CCF, 0.75 D)
and increased compression factor (ICF, 1.75 D).
Methods
This was a double-blind self-controlled study. Subjects were randomly fitted with
CCF in one eye and ICF in the fellow eye. Weekly monitoring of refraction, visual
acuity (VA), external ocular health, and corneal responses were performed over one
month of lens wear and after discontinuation of lens wear until stabilization was
achieved.
Results
Twenty-five subjects, aged 9.4 ± 1.0 years, completed one-month lens wear, of whom
23 completed the washout period. The first fit success rates for CCF and ICF were
93% and 96%, respectively. Myopia, unaided VA, central corneal thickness, anterior
corneal curvatures (K), apical power (AP), and corneal resistance factor (CRF) all
changed significantly during the study period (P < 0.003). Between-eye difference was significant only for myopia reduction (P = 0.001). About 4% and 8% of ICF and CCF eyes were under-corrected. The attempted
target was achieved in about 80% of CCF and 60% of ICF eyes at week 4. At the end
of the washout period (3 weeks), myopia, K, and AP were significantly different compared
to baseline (P < 0.001).
Conclusion
Increasing the compression factor did not affect the first fit success rate and external
ocular health, but did allow faster correction of refractive error within one month
of lens wear. Further investigation is warranted to investigate the long-term effects
of ICF on myopia control compared to CCF.
Keywords
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Article info
Publication history
Published online: November 05, 2019
Accepted:
October 20,
2019
Received in revised form:
September 9,
2019
Received:
January 26,
2019
Identification
Copyright
© 2019 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
