A Coincident Thinning Index for Keratoconus Identification Using OCT Pachymetry and Epithelial Thickness Maps

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Medical Imaging

Background:

• Keratoconus is a progressive thinning disorder of the cornea.
• Accurate detection of early keratoconus is crucial for timely intervention.
• Current diagnostic methods may not sufficiently capture subtle changes in corneal structure.

Purpose of the Study:

• To develop and validate a novel coincident thinning (CTN) index.
• To differentiate between healthy and keratoconic corneas using optical coherence tomography (OCT).
• To assess the CTN index's performance against established keratoconus metrics.

Main Methods:

• Fourier-domain OCT was used to obtain pachymetry and epithelial thickness maps.
• A CTN index was calculated by quantifying co-localized thinning patterns.
• The CTN index was validated using k-fold cross-validation and compared to minimum pachymetry and maximum keratometry.

Main Results:

• The CTN index was significantly larger in keratoconic eyes compared to healthy eyes (P < .0001).
• The index achieved 100% sensitivity for manifest and subclinical keratoconus.
• Overall classification accuracy for the CTN index was 93%, outperforming minimum pachymetry (86%) and maximum keratometry (86%).

Conclusions:

• The CTN index is a sensitive indicator of coincident pachymetric and epithelial thinning.
• This novel index aids in the detection and monitoring of early to moderate keratoconus.
• OCT-derived CTN index offers improved diagnostic capabilities for keratoconus.