Original article
Long-term Results of Riboflavin Ultraviolet A Corneal Collagen Cross-linking for Keratoconus in Italy: The Siena Eye Cross Study

https://doi.org/10.1016/j.ajo.2009.10.021Get rights and content

Purpose

To report the long-term results of 44 keratoconic eyes treated by combined riboflavin ultraviolet A collagen cross-linking in the first Italian open, nonrandomized phase II clinical trial, the Siena Eye Cross Study.

Design

Perspective, nonrandomized, open trial.

Methods

After Siena University Institutional Review Board approval, from September 2004 through September 2008, 363 eyes with progressive keratoconus were treated with riboflavin ultraviolet A collagen cross-linking. Forty-four eyes with a minimum follow-up of 48 months (mean, 52.4 months; range, 48 to 60 months) were evaluated before and after surgery. Examinations comprised uncorrected visual acuity, best spectacle-corrected visual acuity, spherical spectacle-corrected visual acuity, endothelial cells count (I Konan, Non Con Robo; Konan Medical, Inc., Hyogo, Japan), optical (Visante OCT; Zeiss, Jena, Germany) and ultrasound (DGH; Pachette, Exton, Pennsylvania, USA) pachymetry, corneal topography and surface aberrometry (CSO EyeTop, Florence, Italy), tomography (Orbscan IIz; Bausch & Lomb Inc., Rochester, New York, USA), posterior segment optical coherence tomography (Stratus OCT; Zeiss, Jena, Germany), and in vivo confocal microscopy (HRT II; Heidelberg Engineering, Rostock, Germany).

Results

Keratoconus stability was detected in 44 eyes after 48 months of minimum follow-up; fellow eyes showed a mean progression of 1.5 diopters in more than 65% after 24 months, then were treated. The mean K value was reduced by a mean of 2 diopters, and coma aberration reduction with corneal symmetry improvement was observed in more than 85%. The mean best spectacle-corrected visual acuity improved by 1.9 Snellen lines, and the uncorrected visual acuity improved by 2.7 Snellen lines.

Conclusions

The results of the Siena Eye Cross Study showed a long-term stability of keratoconus after cross-linking without relevant side effects. The uncorrected visual acuity and best spectacle-corrected visual acuity improvements were supported by clinical, topographic, and wavefront modifications induced by the treatment.

Section snippets

Methods

To date, 363 eyes with progressive keratoconus have been treated in Siena with the riboflavin UV A corneal collagen cross-linking procedure. The Siena Eye Cross Study9, 10 (phase II nonrandomized open trial) included 44 patients with keratoconus between 10 and 40 years of age with disease progression documented clinically and instrumentally in the last 6 months, minimum corneal thickness of 400 μm in the thinnest point evaluated by Orbscan IIz (Bausch & Lomb, Inc., Rochester, New York, USA),

Results

The mean preoperative pachymetric value measured by central US pachymetry was 450 ± 14.54 μm (range, 422 to 512 μm) and that by optical Orbscan IIz system in the thinnest point was of 438 ± 13.87 μm (range, 408 to 503 μm). During follow-up, the Orbscan II z measurement showed significant underestimation of corneal thickness compared with US and confocal microscopic pachymetric examinations, with a mean of −120 μm in the first 6 months and −70 μm between 6 and 12 months. US and confocal

Discussion

Riboflavin UV A corneal collagen cross-linking currently represents the only pathogenetic approach to progressive keratoconus to delay its progression6, 9, 10 and to reduce the need for donor keratoplasty. The long-term results recorded in the Siena Eye Cross Study confirm another encouraging long-term report in the literature11 and our pilot study9 on riboflavin UV A-induced corneal collagen cross-linking, as far as safety and effectiveness are concerned.12 Analyzing the results, an important

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      A-CXL has a shorter exposure time and showed comparable results in halting keratoconus progression when compared with traditional CXL (Amer et al., 2020; Shajari et al., 2019; Waszczykowska and Jurowski, 2015). Although studies have shown the effectiveness of CXL with high success rates (Caporossi et al., 2010; Hashemi et al., 2013; Kymionis et al., 2014a; O'Brart et al., 2015), deterioration after CXL was reported in some cases, along with steepening of keratometric values, increase in irregular astigmatism, or decrease in corneal thickness. During the 1–6 years of follow-up, the progression rate after initial CXL treatment and after initial traditional epi-off treatment was up to 11% (Gore et al., 2021; Koller et al., 2009; Lenk et al., 2021; Poli et al., 2015), whereas that for epi-on CXL was as high as 23% at 1-year follow-up (Soeters et al., 2015).

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