Fourier Analysis of Keratometric Data in Epithelium Removal versus Epithelial Disruption Corneal Cross-linking


Purpose: To compare epithelium-removal and epithelium-disruption corneal crosslinking (CXL) methods in Fourier analysis of keratometric data and clinical outcomes.

Methods: In this double-masked randomized clinical trial, each eye of 34 patients with bilateral keratoconus was randomly allocated to either the epithelium-removal or epithelium-disruption CXL treatment groups. Ocular examination, refraction, uncorrected and best spectacle-corrected visual acuity (UCVA and BSCVA, respectively) measurements, and Pentacam imaging (keratometry, pachymetry, and Fourier analysis) were performed at baseline and at six-month follow-up period.

Results: Patients’ mean age was 23.3 ± 3.6 years. The preoperative thickness of the thinnest point was 459.20 ± 37.40 μm and 455.80 ± 32.70 μm in the epithelium removal and epithelial-disruption CXL groups, respectively (P = ?). The corresponding figures were 433.50 ± 33.50 μm and 451.90 ± 39.70 μm, respectively, six months after the treatment (P = 0.0001). The irregularity component was 0.030 ± 0.016 μm in the epithelium-removal group and 0.028 ± 0.011 μm in the epithelium-disruption group preoperatively (P = ?). This measurement was 0.031 ± 0.016 μm and 0.024 ± 0.009 μm, respectively at month 6 (P = 0.04). The epithelium-disruption CXL group had better results in terms of the thickness of the thinnest point and the irregularity component as compared to the epithelium-removal group. The two study groups were comparable in spherical equivalent, mean keratometry, UCVA, BSCVA, or other Fourier analysis components (spherical R min, spherical eccentricity, central, peripheral regular astigmatism, and maximum decentration) (P > 0.05).

Conclusion: This study shows that epithelium-disruption CXL is superior to epithelium removal CXL regarding the short-term changes in pachymetry and corneal irregularity. Other evaluated parameters were comparable between the two techniques within the six-month follow-up period.


Corneal Cross Linking, Epithelium Disruption, Epithelium Removal, Fourier Analysis, Keratoconus, Randomized Controlled Trial, Transepithelial

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