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Related Experiment Videos

Astigmatic changes in orthokeratology.

Sin Wan Cheung1, Pauline Cho, Ben Chan

  • 1School of Optometry, The Hong Kong Polytechnic University, Hong Kong SAR, China. sopeggy@inet.polyu.edu.hk

Optometry and Vision Science : Official Publication of the American Academy of Optometry
|October 22, 2009
PubMed
Summary

Orthokeratology (ortho-k) significantly alters refractive astigmatism but not corneal toricity in young patients. This study found ortho-k did not induce astigmatism in non-astigmatic subjects.

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Area of Science:

  • Ophthalmology
  • Optometry
  • Corneal Refractive Surgery

Background:

  • Orthokeratology (ortho-k) is a non-surgical method for correcting refractive errors.
  • Understanding its effects on astigmatism and corneal shape is crucial for patient management.

Purpose of the Study:

  • To compare changes in refractive astigmatism and corneal toricity after orthokeratology (ortho-k) treatment.
  • To utilize Thibos vector analysis for evaluating these changes.

Main Methods:

  • Reviewed records of 74 young patients (7-16 years) undergoing spherical ortho-k treatment for at least 6 months.
  • Analyzed manifest refractive error and topographic data using Thibos vectors (RJ 0, RJ 45, CJ 0, CJ 45).
  • Compared changes between astigmatic and non-astigmatic groups.

Main Results:

  • Spherical ortho-k significantly changed refractive astigmatism (RJ 0 and RJ 45) in astigmatic patients.
  • No significant changes in corneal toricity were observed.
  • Correlations between refractive astigmatism changes and initial values were found, but explained limited variance (21-55%).

Conclusions:

  • Spherical ortho-k induces significant changes in refractive astigmatism but not corneal toricity.
  • No induced astigmatism was observed in non-astigmatic subjects.
  • The relationship between initial refractive astigmatism and treatment-induced changes is complex and not fully explained by current models.