Abstract
Purpose To compare epithelium-removal and epithelium-disruption corneal crosslinking (CXL) methods in Fourier analysis of keratometric data and clinical outcomes.MethodsIn 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 > 0.05). The corresponding figures were 433.50 33.50 µm and 451.90 39.70 µm, respectively, six months after the treatment (P = 0.0001). Irregularity component of the fourier analysis was 0.030 0.016 µm in the epithelium-removal group and 0.028 0.011 µm in the epithelium-disruption group preoperatively (P > 0.05). 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).ConclusionThis 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.
Highlights
Keratoconus is a non-inflammatory bilateral progressive corneal ectasia characterized by corneal stromal thinning, protrusion, and irregular astigmatism that results in light scattering
A total of 68 eyes of 34 patients (10 men and 24 women) with bilateral keratoconus were included in this randomized clinical trial (RCT)
A fair prognosis for a young patient diagnosed with keratoconus was expected and the progressive nature of the disease in many cases led to corneal transplantation
Summary
Keratoconus is a non-inflammatory bilateral progressive corneal ectasia characterized by corneal stromal thinning, protrusion, and irregular astigmatism that results in light scattering. Ultra-violet A is used to enhance crosslinking between adjacent corneal collagen fibers.[5] Recently, some modifications were made to reduce the manipulation of the corneal epithelium, decreasing the initial pain, visual discomfort, and stromal haziness.[8] One suggested procedure is trans-epithelial CXL in which hypo-osmolar riboflavin is applied to the cornea through an intact epithelium The efficacy of this modification, was reported to be less than that of the conventional method in some studies.[9, 10] partial epitheliumremoval CXL was developed, which uses vertical and horizontal strips of de-epithelization using a custom-designed surgical instrument (Daya epithelium disruptor). The safety, efficacy, and better tolerability of this method have been reported in recent publications.[11,12,13,14]
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