Epithelial Thickness Mapping: A New Norm in Orthokeratology Fitting?

Overview

Epithelial thickness mapping (ETM) using anterior segment optical coherence tomography (AS-OCT) is emerging as a valuable tool in orthokeratology (ortho-k) for myopia correction and control. ETM allows precise measurement of corneal epithelial changes pre- and post-ortho-k treatment, enhancing lens fitting and treatment zone assessment.

Background

Orthokeratology is a well-established method for correcting myopia by reshaping the cornea through overnight lens wear, providing patients freedom from daily glasses or contact lenses. The treatment effect primarily involves remodeling of the corneal epithelium, which was previously difficult to measure accurately. Recent advances in AS-OCT technology now enable detailed epithelial thickness mapping, allowing clinicians to quantify epithelial changes and optimize ortho-k lens fitting. Normal epithelial thickness averages around 53.4µm ± 4.6µm, and ortho-k typically induces central epithelial thinning with peripheral thickening.

Data Highlights

Normal epithelial thickness: 53.4µm ± 4.6µm (Abtahi et al, 2024).
Case example: 13-year-old male with -3.00 DS OD and -3.00 -1.00 x 146 OS underwent ortho-k.
Post-treatment ETM showed central epithelial thinning in the right eye with appropriate alignment.
Left eye showed epithelial thinning inferiorly with slight lens decentration affecting treatment zone positioning.

Key Findings

• Ortho-k treatment induces central corneal epithelial thinning and peripheral thickening, measurable by ETM.
• AS-OCT enables simultaneous measurement of epithelial thickness and corneal topography, improving assessment accuracy.
• ETM helps identify treatment zone location and lens alignment, critical for optimal visual outcomes.
• Case study demonstrated ETM utility in detecting lens decentration and epithelial remodeling differences between eyes.
• ETM may become a standard component of ortho-k fitting protocols to enhance treatment precision.

Clinical Implications

Incorporating epithelial thickness mapping into orthokeratology practice allows clinicians to objectively evaluate corneal remodeling and lens fit, potentially improving treatment outcomes and patient satisfaction. ETM can guide adjustments in lens parameters to center the treatment zone and optimize myopic correction. This technology supports more personalized and effective myopia management strategies.

Conclusion

Epithelial thickness mapping represents a promising advancement in orthokeratology, offering detailed insights into corneal changes that can refine lens fitting and treatment monitoring. As ETM technology becomes more accessible, it may establish a new standard of care in ortho-k practice.

References

1. Bullimore MA, Johnson LA. 2020 -- Overnight orthokeratology
2. González-Pérez J, Sánchez-García A, Parafita MA. 2023 -- Epithelial and stromal thickness profile and lens decentration in myopic orthokeratology
3. Abtahi MA, Beheshtnejad AH, Latifi G, et al. 2024 -- Corneal Epithelial Thickness Mapping: A Major Review