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A novel fitting algorithm for alignment curve radius estimation using corneal elevation data in orthokeratology lens

Lu Zhang1, Yue Zhang2, Yanlin Liu1

  • 1Department of Ophthalmology & Clinical Centre of Optometry, Peking University People's Hospital, Beijing, 100044, China; College of Optometry, Peking University Health Science Centre, Beijing, 100044, China; Beijing Key Laboratory for the Diagnosis and Treatment of Retinal and Choroid Diseases, Beijing, 100044, China.

Contact Lens & Anterior Eye : the Journal of the British Contact Lens Association
|October 10, 2017
PubMed
Summary

A new fitting algorithm for orthokeratology (ortho-k) lenses significantly reduced trial lens fittings. This method improves the estimation of alignment curve radius and astigmatism, potentially shortening fitting times.

Keywords:
ChildrenContact lensCorneaMyopiaOrthokeratology

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Area of Science:

  • Ophthalmology
  • Optometry
  • Biomedical Engineering

Background:

  • Orthokeratology (ortho-k) is a non-surgical method to correct myopia.
  • Accurate estimation of the alignment curve (AC) radius is crucial for successful ortho-k lens fitting.
  • Current methods for AC radius estimation can be time-consuming and may require multiple lens trials.

Purpose of the Study:

  • To evaluate a novel fitting algorithm for estimating the alignment curve (AC) radius during orthokeratology lens trials.
  • To compare the efficacy of the novel algorithm with the traditional method in terms of fitting time and accuracy.

Main Methods:

  • A novel fitting algorithm using corneal elevation data and succedent toric fitting was developed.
  • Alignment curve radii were estimated using both the novel algorithm and the traditional method (flat K readings and eccentricity values).
  • Corneal topography and fluorescein analysis were used to determine final lens parameters. Lens trial numbers and parameter consistencies were analyzed.

Main Results:

  • The novel algorithm required significantly fewer lens trials (1.2±0.4) compared to the traditional method (1.8±0.7) (p=0.001).
  • The novel algorithm demonstrated higher accuracy in estimating the AC radius of the first trial lenses, with R square values of 0.994 versus 0.927 for the traditional method.
  • Similar improvements in accuracy were observed for astigmatism estimation.

Conclusions:

  • A two-step fitting algorithm utilizing corneal elevation data provides a more accurate estimation of ortho-k lens parameters.
  • This novel approach can potentially reduce the number of lens trials needed for orthokeratology fitting.
  • Improved estimation accuracy may lead to better lens fitting status and patient outcomes.