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Corneal Cross-Linking Pre-Operative Assessment Using OCT Full-Field Corneal Pachymetry Compared to Ultrasonic Pachymetry
Corey J. Miller, MD
Stephen C. Kaufman, MD, PhD
Joseph Bogaard, MD
Chase Liaboe, MD
Alessandro Meduri, MD
Keratoconus, Pachymetry, corneal collagen cross linking, Corneal cross linking, CXL, Ultrasonic pachymetry, Ocular Coherence Tomography, OCT.
Purpose: This study compares single central corneal pachymetry measurements to the full-field ocular coherence tomography (OCT) pachymetry’s minimal corneal thickness measurements to better identify patients who should be excluded from corneal cross-linking due to insufficient corneal thickness requirements.
Methods: A total of 32 eyes from 16 patients were identified. Inclusion criteria included patients with keratoconus who had both single central corneal ultrasonic pachymetry and full-field OCT – pachymetry measurements performed during pre-operative cross-linking evaluation.
Results: The mean central corneal thickness for single ultrasound pachymetry was 461.3 microns (95% CI 443- 479.6 microns) and for full-field OCT-pachymetry it was 415.4 (95% CI 391.1 – 439.7 microns). The difference was statistically significant (p = 0.000098) as calculated by a paired student’s T test. Five of the 32 subjects (15.5%) had OCT full-field corneal pachymetry measurements less than 400 microns, while the single ultrasonic measurement was greater than 400 microns in all but 2 subjects.
Conclusions: A significant difference was noted in corneal pachymetry measurements comparing single ultrasound pachymeter to the minimal corneal thickness on full-field OCT pachymetry during the assessment for corneal cross-linking. Reliance on single ultrasound pachymetry measurements could lead to treatment of corneas with inadequate corneal thickness and result in endothelial cell damage during corneal cross-linking.