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      Long term results of accelerated 9 mW corneal crosslinking for early progressive keratoconus: the Siena Eye-Cross Study 2


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          To assess clinical results of the 9 mW/5.4 J/cm 2 accelerated crosslinking (ACXL) in the treatment of progressive keratoconus (KC) over a span of 5 years.


          The prospective open non-randomized interventional study (Siena Eye-Cross Study 2) included 156 eyes of 112 patients with early progressive KC undergoing the Epi-Off 9 mW/5.4 J/cm 2 ACXL at the Siena Crosslinking Centre, Italy. The mean age was 18.05 ± 5.6 years. The 20-min treatments were performed using the New KXL I (Avedro, Waltham, USA), 10 min of 0.1% HPMC Riboflavin soaking (VibeX Rapid, Avedro, Waltham, USA) and 10 min of continuous-light UV-A irradiation. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), Kmax, coma, minimum corneal thickness (MCT), surface asymmetry index (SAI), endothelial cell count (ECC) were measured, and corneal OCT performed.


          UDVA and CDVA improved significantly at the 3rd ( P = 0.028), Δ + 0.17 Snellen lines and 6th postoperative month, respectively ( P < 0.001), Δ + 0.23 Snellen lines. Kmax improved at the 6th postoperative month ( P = 0.03), Δ − 1.49 diopters from the baseline value. Also, coma aberration value improved significantly ( P = 0.004). A mild temporary haze was recorded in 14.77% of patients without affecting visual acuity and without persistent complications. Corneal OCT revealed a mean demarcation line depth at 332.6 ± 33.6 μm.


          The 5-year results of Epi-Off 9 mW/5.4 J/cm 2 ACXL demonstrated statistically significant improvements in UCVA and CDVA, corneal curvature and corneal higher-order aberrations which confers a long-term stability for progressive ectasia. Based on the results of the Siena Eye-Cross Study 2, the 9 mW/5.4 J/cm 2 ACXL is a candidate to be  the natural evolution of Epi-Off CXL treatment for the management of early progressive corneal ectasia, and thus optimize clinic workflow.

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          Riboflavin/ultraviolet-a–induced collagen crosslinking for the treatment of keratoconus

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            Long-term results of riboflavin ultraviolet a corneal collagen cross-linking for keratoconus in Italy: the Siena eye cross study.

            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. Perspective, nonrandomized, open trial. 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). 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. 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. Copyright 2010 Elsevier Inc. All rights reserved.
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              Safety of UVA-riboflavin cross-linking of the cornea.

              To study potential damage to ocular tissue during corneal collagen cross-linking (X-linking) by means of the riboflavin/UVA (370 nm) approach. Comparison of the currently used technique with officially accepted guidelines regarding direct UV damage and the damage created by the induced free radicals (photochemical damage). The currently used UVA radiant exposure of 5.4 mJ/cm and the corresponding irradiance of 3 mW/cm2 is below the known damage thresholds of UVA for the corneal endothelium, lens, and retina. Regarding the photochemical damage caused by the free radicals, the damage thresholds for keratocytes and endothelial cells are 0.45 and 0.35 mW/cm, respectively. In a 400-microm-thick cornea saturated with riboflavin, the irradiance at the endothelial level was 0.18 mW/cm, which is a factor of 2 smaller than the damage threshold. After corneal X-linking, the stroma is depopulated of keratocytes approximately 300 microm deep. Repopulation of this area takes up to 6 months. As long as the cornea treated has a minimum thickness of 400 microm (as recommended), the corneal endothelium will not experience damage, nor will deeper structures such as lens and retina. The light source should provide a homogenous irradiance, avoiding hot spots.

                Author and article information

                Eye Vis (Lond)
                Eye Vis (Lond)
                Eye and Vision
                BioMed Central (London )
                1 May 2021
                1 May 2021
                : 8
                : 16
                [1 ]Departmental Ophthalmology Unit, USL Toscana Sud-Est, Campostaggia, Siena, Italy
                [2 ]Siena Crosslinking Center, 53035, Monteriggioni, Siena, Italy
                [3 ]GRID grid.412282.f, ISNI 0000 0001 1091 2917, Department of Ophthalmology, , C.G. Carus University Hospital, ; Dresden, Germany
                [4 ]GRID grid.488809.5, ELZA Institute, ; Dietikon, Switzerland
                [5 ]GRID grid.8591.5, ISNI 0000 0001 2322 4988, Medical Faculty, , University of Geneva, ; Geneva, Switzerland
                [6 ]GRID grid.42505.36, ISNI 0000 0001 2156 6853, Roski Eye Institute, University of Southern California, ; Los Angeles, CA USA
                [7 ]GRID grid.412899.f, ISNI 0000 0000 9117 1462, Department of Ophthalmology, , University of Wenzhou, ; Wenzhou, China
                [8 ]GRID grid.411249.b, ISNI 0000 0001 0514 7202, Department of Ophthalmology, , Federal University of Sao Paulo, ; Sao Paulo, Brazil
                [9 ]Ashraf Armia Eye Clinic and Al Watany Eye Hospital, Watany Research and Development Centre, Cairo, Egypt
                [10 ]GRID grid.411489.1, ISNI 0000 0001 2168 2547, Department of Ophthalmology, , University Magna Graecia of Catanzaro, ; Catanzaro, Italy
                © The Author(s) 2021

                Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

                : 8 November 2020
                : 9 April 2021
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                © The Author(s) 2021

                crosslinking,keratoconus,accelerated crosslinking,epi-off,dresden accelerated protocol,9 mw crosslinking,cxl,acxl


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