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Celik-Buyuktepe T, Ucakhan OO. Comparative Evaluation of Anterior Segment Optical Coherence Tomography Findings Following Accelerated Corneal Crosslinking Protocols Using Different Riboflavin Formulations and Soaking Durations. Curr Eye Res 2024:1-9. [PMID: 39090846 DOI: 10.1080/02713683.2024.2385441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Revised: 07/11/2024] [Accepted: 07/22/2024] [Indexed: 08/04/2024]
Abstract
PURPOSE To comparatively evaluate the influence of different riboflavin formulations and soaking durations on the anterior segment optical coherence tomography (AS-OCT) findings following accelerated corneal crosslinking (ACXL) at 9 mW/cm2 for in progressive keratoconus. METHODS In this prospective study, consecutive patients with progressive keratoconus were randomized into 4 groups. Group 1: hydroxypropyl methylcellulose (HPMC)-based riboflavin for 10 min; Group 2: HPMC-based riboflavin for 20 min; Group 3: dextran-based riboflavin (0.1%) for 30 min. Riboflavin soaking was followed by ultraviolet-A irradiation at 9 mW/cm2 for 10 min in all three groups. Group 4 underwent conventional CXL (CCXL) using Dresden protocol. The AS-OCT features of the crosslinked cornea were evaluated at postoperative month 1 and correlated to the clinical outcomes at postoperative month 12. RESULTS The study enrolled 26 eyes of 26 patients in each group. In groups 1 and 2, the AS-OCT findings were similar (p > .05) and the demarcation lines depth (DLD) were deep as obtained following CCXL. The DLD was significantly shallower in group 3 compared to the other groups (p < .01). There were no between-group differences in regards to the visual, refractive, keratometric, and tomographic outcomes at postoperative month 12. No significant endothelial cell loss or any other clinically significant adverse event was encountered in any patient's eye at 12 months follow-up. CONCLUSION Although structural variations were noted in the crosslinked cornea, DLDs observed following ACXL (9 mW/cm2) using HPMC-based solution for 10 or 20 min were similar to those observed following CCXL. Whereas, ACXL (9 mW/cm2) using dextran-based solution for 30 min resulted in the shallowest DLD. Despite these remodeling differences, the visual, refractive and tomographic outcomes of all groups were comparable at postoperative 1-year follow-up. Studies with a greater number of patients and longer follow-ups are required to establish any relation between AS-OCT characteristics of crosslinked cornea and ACXL efficacy.
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Affiliation(s)
| | - Omur O Ucakhan
- Department of Ophthalmology, Ankara University School of Medicine, Ankara, Turkey
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Caruso C, D'Andrea L, Troisi M, Rinaldi M, Piscopo R, Troisi S, Costagliola C. Corneal collagen cross-linking in patients with keratoconus from the Dresden protocol to customized solutions: theoretical basis. Int J Ophthalmol 2024; 17:951-962. [PMID: 38766341 PMCID: PMC11074195 DOI: 10.18240/ijo.2024.05.21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 02/02/2024] [Indexed: 05/22/2024] Open
Abstract
Keratoconus is an ectatic condition characterized by gradual corneal thinning, corneal protrusion, progressive irregular astigmatism, corneal fibrosis, and visual impairment. The therapeutic options regarding improvement of visual function include glasses or soft contact lenses correction for initial stages, gas-permeable rigid contact lenses, scleral lenses, implantation of intrastromal corneal ring or corneal transplants for most advanced stages. In keratoconus cases showing disease progression corneal collagen crosslinking (CXL) has been proven to be an effective, minimally invasive and safe procedure. CXL consists of a photochemical reaction of corneal collagen by riboflavin stimulation with ultraviolet A radiation, resulting in stromal crosslinks formation. The aim of this review is to carry out an examination of CXL methods based on theoretical basis and mathematical models, from the original Dresden protocol to the most recent developments in the technique, reporting the changes proposed in the last 15y and examining the advantages and disadvantages of the various treatment protocols. Finally, the limits of non-standardized methods and the perspectives offered by a customization of the treatment are highlighted.
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Affiliation(s)
- Ciro Caruso
- Corneal Transplant Center, Pellegrini Hospital, Via Portamedina alla Pignasecca 41, Napoli 80127, Italy
| | - Luca D'Andrea
- Eye Clinic, Department of Neurosciences, Reproductive and Odontostomatological Sciences, University of Naples Federico II, Naples 80131, Italy
- Public Health Department, University of Naples Federico II, Naples 80131, Italy
| | - Mario Troisi
- Eye Clinic, Department of Neurosciences, Reproductive and Odontostomatological Sciences, University of Naples Federico II, Naples 80131, Italy
| | - Michele Rinaldi
- Eye Clinic, Department of Neurosciences, Reproductive and Odontostomatological Sciences, University of Naples Federico II, Naples 80131, Italy
| | - Raffaele Piscopo
- Eye Clinic, Department of Neurosciences, Reproductive and Odontostomatological Sciences, University of Naples Federico II, Naples 80131, Italy
| | - Salvatore Troisi
- Salerno Hospital University, Ophthalmologic Unit, Baronissi, Campania 84131, Italy
| | - Ciro Costagliola
- Eye Clinic, Department of Neurosciences, Reproductive and Odontostomatological Sciences, University of Naples Federico II, Naples 80131, Italy
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Regnault G, Kirby MA, Wang RK, Shen TT, O’Donnell M, Pelivanov I. Possible depth-resolved reconstruction of shear moduli in the cornea following collagen crosslinking (CXL) with optical coherence tomography and elastography. BIOMEDICAL OPTICS EXPRESS 2023; 14:5005-5021. [PMID: 37791258 PMCID: PMC10545180 DOI: 10.1364/boe.497970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/10/2023] [Accepted: 08/16/2023] [Indexed: 10/05/2023]
Abstract
Corneal collagen crosslinking (CXL) is commonly used to prevent or treat keratoconus. Although changes in corneal stiffness induced by CXL surgery can be monitored with non-contact dynamic optical coherence elastography (OCE) by tracking mechanical wave propagation, depth dependent changes are still unclear if the cornea is not crosslinked through the whole depth. Here, phase-decorrelation measurements on optical coherence tomography (OCT) structural images are combined with acoustic micro-tapping (AµT) OCE to explore possible reconstruction of depth-dependent stiffness within crosslinked corneas in an ex vivo human cornea sample. Experimental OCT images are analyzed to define the penetration depth of CXL into the cornea. In a representative ex vivo human cornea sample, crosslinking depth varied from ∼100 µm in the periphery to ∼150 µm in the cornea center and exhibited a sharp in-depth transition between crosslinked and untreated areas. This information was used in an analytical two-layer guided wave propagation model to quantify the stiffness of the treated layer. We also discuss how the elastic moduli of partially CXL-treated cornea layers reflect the effective engineering stiffness of the entire cornea to properly quantify corneal deformation.
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Affiliation(s)
- Gabriel Regnault
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Mitchell A. Kirby
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Ruikang K. Wang
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
| | - Tueng T. Shen
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
- School of Medicine, University of Washington, Seattle, WA, USA
| | - Matthew O’Donnell
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Ivan Pelivanov
- Department of Bioengineering, University of Washington, Seattle, WA, USA
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Regnault G, Kirby MA, Wang RK, Shen TT, O’Donnell M, Pelivanov I. Possible depth-resolved reconstruction of shear moduli in the cornea following collagen crosslinking (CXL) with optical coherence tomography and elastography. ARXIV 2023:arXiv:2306.15018v1. [PMID: 37426451 PMCID: PMC10327230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Corneal collagen crosslinking (CXL) is commonly used to prevent or treat keratoconus. Although changes in corneal stiffness induced by CXL surgery can be monitored with non-contact dynamic optical coherence elastography (OCE) by tracking mechanical wave propagation, depth dependent changes are still unclear if the cornea is not crosslinked through the whole depth. Here, phase-decorrelation measurements on optical coherence tomography (OCT) structural images are combined with acoustic micro-tapping (A$\mu$T) OCE to explore possible reconstruction of depth-dependent stiffness within crosslinked corneas in an ex vivo human cornea sample. Experimental OCT images are analyzed to define the penetration depth of CXL into the cornea. In a representative ex vivo human cornea sample, crosslinking depth varied from $\sim 100\mu m$ in the periphery to $\sim 150\mu m$ in the cornea center and exhibited a sharp in-depth transition between crosslinked and untreated areas. This information was used in an analytical two-layer guided wave propagation model to quantify the stiffness of the treated layer. We also discuss how the elastic moduli of partially CXL-treated cornea layers reflect the effective engineering stiffness of the entire cornea to properly quantify corneal deformation.
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Affiliation(s)
- Gabriel Regnault
- Department of Bioengineering, University of Washington, Seattle, USA
| | - Mitchell A. Kirby
- Department of Bioengineering, University of Washington, Seattle, USA
| | - Ruikang K. Wang
- Department of Bioengineering, University of Washington, Seattle, USA
- Department of Ophthalmology, University of Washington, Seattle, USA
| | - Tueng T. Shen
- Department of Ophthalmology, University of Washington, Seattle, USA
- School of Medicine, University of Washington, Seattle, USA
| | - Matthew O’Donnell
- Department of Bioengineering, University of Washington, Seattle, USA
| | - Ivan Pelivanov
- Department of Bioengineering, University of Washington, Seattle, USA
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Parsa S, Rodriguez A, Robertson DM, Bowman RW, Petroll WM. Temporal and Spatial Assessment of the Corneal Response to UV Cross-Linking Using 3-Dimensional In Vivo Confocal Microscopy. Eye Contact Lens 2022; 48:308-312. [PMID: 35333808 PMCID: PMC9232861 DOI: 10.1097/icl.0000000000000892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/21/2021] [Indexed: 11/25/2022]
Abstract
ABSTRACT The goal of this study was to evaluate the temporal and spatial pattern of wound healing following UV corneal cross-linking (CXL) using 3-dimensional (3-D) confocal imaging in vivo. Using a modified Heidelberg Retinal Tomograph with Rostock Corneal Module confocal microscope, we performed 3-D scans on two patients at multiple time points after CXL. Patient 1 showed a normal post-CXL wound healing response, with initial subbasal nerve loss and keratocyte apoptosis in the anterior stroma, followed by partial restoration of both the nerve plexus and stromal keratocytes by 6 months. In patient 2, in addition to anterior corneal damage, pyknotic nuclei were observed in the posterior stroma 7 days after CXL. Acellular areas were present in the posterior stroma at 3 months, with only partial keratocyte repopulation at 6 months. Regeneration of the subbasal nerve plexus was also delayed. Three-dimensional confocal imaging allowed these unusual wound healing responses to be identified in the absence of any corresponding clinical observations.
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Affiliation(s)
- Shyon Parsa
- Southwestern Medical School, UT Southwestern Medical Center, Dallas, TX, USA
| | - Alejandro Rodriguez
- Southwestern Medical School, UT Southwestern Medical Center, Dallas, TX, USA
| | | | - R. Wayne Bowman
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX, USA
| | - W. Matthew Petroll
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX, USA
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Nishida T, Kojima T, Kataoka T, Isogai N, Yoshida Y, Nakamura T. Evaluation of the Relationship Between the Changes in the Corneal Biomechanical Properties and Changes in the Anterior Segment OCT Parameters Following Customized Corneal Cross-Linking. Clin Ophthalmol 2022; 16:1909-1923. [PMID: 35711971 PMCID: PMC9192785 DOI: 10.2147/opth.s361836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 05/12/2022] [Indexed: 11/23/2022] Open
Abstract
Purpose Patients and Methods Results Conclusion
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Affiliation(s)
| | - Takashi Kojima
- Nagoya Eye Clinic, Nagoya, Japan
- Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
- Correspondence: Takashi Kojima, Department of Ophthalmology, Keio University School of Medicine, Shinanomachi 35, Shinjuku-ku, Tokyo, Japan, Tel +81-3-5363-2012, Fax +81-3-3359-7027, Email
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Xanthopoulou K, Milioti G, Daas L, Munteanu C, Seitz B, Flockerzi E. Accelerated corneal crosslinking causes pseudoprogression in keratoconus within the first 6 weeks without affecting posterior corneal curvature. Eur J Ophthalmol 2022; 32:2565-2576. [PMID: 35535408 DOI: 10.1177/11206721221099257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
PURPOSE To evaluate the effectiveness of epithelium-off (epi-off) accelerated corneal crosslinking (A-CXL, 9 mW/cm2, 10 min) in adult keratoconus (KC) patients. METHODS The study included 151 KC corneas (124 patients) after A-CXL. The parameters best corrected visual acuity (BCVA) and the tomographic readings (Pentacam HR, Oculus, Germany) were analysed at 24, 12 and 6 months preoperatively, prior to surgery; and 6 weeks, 6 months, 1, 2 and >2 years postoperatively. The demarcation line was assessed by anterior segment optical coherence tomography (Tomey SS-1000, CASIA 2 (Tomey, Nagoya, Japan)). RESULTS Comparing pre- to postoperative findings 6 weeks after A-CXL with paired t-test, the anterior steep (46.8 ± 4.0|47.1 ± 4.1), flat (50.2 ± 4.3|50.6 ± 4.6) and maximal keratometry (57.6 ± 6.8|58.3 ± 6.8) increased (p < 0.05), while the thinnest pachymetry decreased significantly (459 ± 39|444 ± 42, p < 0.05). Lateron, however, there was a decreasing anterior flat (1, 2 and >2 years; p < 0.0001), mean (1 year; p = 0.01 and 2 years; p = 0.03) and maximal keratometry (1, 2 and >2 years; p < 0.0001). The posterior corneal keratometry readings did not change significantly until >2 years after A-CXL (MANOVA; steep, p = 0.008; flat, p = 0.027; mean, p = 0.007). The mean depth of the demarcation line was 242 ± 62 µm (53.6%). The preoperative logMAR BCVA (0.35 ± 0.02) decreased 6 weeks after A-CXL (0.39 ± 0.03) followed by a continuous improvement until the latest follow-up (0.18 ± 0.04). CONCLUSION A-CXL constitutes a successful method for KC stabilization. Signs of KC progression occur within the first 6 weeks postoperatively ("pseudoprogression"), but this is not indicative of the long-term effect.
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Affiliation(s)
| | - Georgia Milioti
- Department of Ophthalmology, 39072Saarland University Medical Center, Homburg, Germany
| | - Loay Daas
- Department of Ophthalmology, 39072Saarland University Medical Center, Homburg, Germany
| | - Cristian Munteanu
- Department of Ophthalmology, 39072Saarland University Medical Center, Homburg, Germany
| | - Berthold Seitz
- Department of Ophthalmology, 39072Saarland University Medical Center, Homburg, Germany
| | - Elias Flockerzi
- Department of Ophthalmology, 39072Saarland University Medical Center, Homburg, Germany
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Brar S, Roopashree CR, Ganesh S. Incidence of Ectasia After SMILE From a High-Volume Refractive Surgery Center in India. J Refract Surg 2021; 37:800-808. [PMID: 34914554 DOI: 10.3928/1081597x-20210812-03] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
PURPOSE To report the incidence of ectasia after small incision lenticule extraction (SMILE) in a high-volume refractive surgery center in India. METHODS To derive the incidence of ectasia after SMILE, all eyes that underwent SMILE or SMILE Xtra (SMILE combined with prophylactic accelerated corneal cross-linking) from November 2012 to August 2019 were retrospectively analyzed. Furthermore, these cases were classified as being "normal" or "borderline" based on certain predefined criteria. Only eyes with a minimum follow-up of 12 months were included. RESULTS Of the total 7,024 eyes analyzed, 6,619 eyes underwent SMILE, of which 10 eyes developed ectasia at a mean interval of 21.3 months, making the incidence of ectasia after SMILE 0.15%. Of these 10 eyes with ectasia, 2 eyes had normal preoperative topography, whereas the remaining 8 eyes were borderline as per the predefined criteria. Retrospective data analysis revealed that 6,025 of 7,024 eyes were normal and thus suitable for a standard SMILE procedure, whereas 999 eyes were borderline, of which 594 eyes underwent SMILE and 405 eyes underwent SMILE Xtra. The incidence of ectasia in borderline eyes undergoing SMILE was 0.80% (8 of 999) versus 0% (none) for borderline eyes undergoing SMILE Xtra (chi square, P < .05). CONCLUSIONS The incidence of ectasia after SMILE in the early postoperative period was 0.15%, with borderline eyes accounting for most cases. Borderline eyes treated with SMILE Xtra did not progress to ectasia, potentially suggesting a protective role of simultaneous CXL. [J Refract Surg. 2021;37(12):800-808.].
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Long-term visual, refractive, tomographic and aberrometric outcomes of corneal collagen crosslinking (CXL) with or without hypoosmolar riboflavin solution in the treatment of progressive keratoconus patients with thin corneas. Graefes Arch Clin Exp Ophthalmol 2021; 260:1225-1235. [PMID: 34837507 DOI: 10.1007/s00417-021-05314-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 06/27/2021] [Accepted: 07/01/2021] [Indexed: 10/19/2022] Open
Abstract
PURPOSE To evaluate the long-term visual, refractive, tomographic, and aberrometric outcomes of corneal collagen crosslinking (CXL) with or without hypoosmolar riboflavin solution in the treatment of progressive keratoconus patients with thin corneas. METHODS Charts of consecutive progressive keratoconus patients with thinnest corneal thickness less than 470 µm who underwent corneal collagen CXL with or without hypoosmolar riboflavin solution and using a standardized protocol for treatment and examinations were analyzed retrospectively. The indication for hypoosmolar riboflavin use was a central corneal thickness less than 400 µm as measured by ultrasound pachymetry after epithelial debridement and before exposure to ultraviolet A (UVA) light. Uncorrected distance visual acuity (UDVA), best spectacle-corrected distance visual acuity (CDVA), manifest refraction, slit lamp biomicroscopy, corneal tomography, corneal aberrometry, and endothelial cell counts were evaluated at baseline and yearly at all postoperative follow-up examinations until month 36. The outcomes of corneal CXL procedure performed using hypoosmolar riboflavin were compared to those performed using the standard procedure. RESULTS Twenty-three eyes (19 patients) were treated using hypoosmolar riboflavin application, and 30 eyes (28 patients) were treated using the standard procedure. Compared to baseline, the mean UDVA, CDVA, and keratometric readings improved statistically significantly in both groups at postoperative year 3, without any statistically significant between-group differences. Progression was not observed in any patient eye in either group. No significant endothelial cell loss and no sight threating complication were observed in any patient eye. CONCLUSION At 3 years follow-up, the safety and efficacy of CXL using hypoosmolar riboflavin solution seems to be similar to that of standard CXL in progressive keratoconic eyes with thin corneas. The visual, refractive, keratometric, tomographic and aberrometric outcomes of the two procedures were comparable, as well.
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Corneal Cross-Linking as Treatment in Pediatric Keratoconus: Comparison of Two Protocols. J Ophthalmol 2021; 2021:2659828. [PMID: 34777857 PMCID: PMC8580685 DOI: 10.1155/2021/2659828] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 10/14/2021] [Accepted: 10/16/2021] [Indexed: 11/17/2022] Open
Abstract
Introduction Keratoconus is a progressive corneal disease commonly treated by collagen cross-linking (CXL). Accelerated protocols have recently become common. This study sought to compare the outcomes of accelerated and standard CXL in terms of visual acuity, keratometry, and tomographic parameters in pediatric population. Methods We retrospectively reviewed the files of pediatric patients who underwent standard and accelerated CXL for keratoconus in our hospital, between October 2014 and March 2018. Changes in uncorrected distance visual acuity (UCDVA), best corrected distance visual acuity (BCDVA), tomographic keratometry parameters (Kmax, Ksteep, Kflat, Kmean), and endothelial density count (EDC) were assessed before and at 6 and 12 months following treatment. The analysis included intergroup and intragroup comparisons. Results This study included 53 eyes (44 patients). Fourteen eyes were treated with standard CXL (S-CXL, 3 mW/cm2, 30 min), while 39 underwent accelerated CXL (A-CXL, 9 mW/cm2, 10 min). Intergroup comparison found insignificant differences between groups, with the exception of better results for UCDVA in the S-CXL group after 12 months (P = 0.03). In this study, there was no significant difference between the two protocols postoperatively in BCDVA, Kmax, Kmean, pachymetry, or corneal astigmatism. Conclusion A-CXL is as safe and effective as S-CXL for stabilizing progressive keratoconus in pediatric population. Larger-sample-size studies with a longer follow-up time are required. Considering the long-term results of 9 mW A-CXL and its safety and efficacy profile, it should be preferred to S-CXL for reducing treatment time and improving patients' comfort.
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Näslund S, Rehnman JB, Fredriksson A, Behndig A. Comparison of two annular photorefractive intrastromal cross-linking protocols in high oxygen for low-grade myopia through 24-month follow-up. Acta Ophthalmol 2021; 100:549-558. [PMID: 34609048 DOI: 10.1111/aos.15035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 08/19/2021] [Accepted: 09/22/2021] [Indexed: 11/29/2022]
Abstract
PURPOSE To compare two annular epithelium-on (epi-on) high oxygen photorefractive intrastromal cross-linking (PiXL) illuminations protocols for treatment of low-grade myopia. METHODS In this randomized, single-masked, intra-individually comparative study, healthy individuals with bilateral low-grade myopia (manifest refractive spherical equivalent (MRSE) -0.75 diopters (D) to -2.50 D) were treated with high oxygen epi-on PiXL. One eye was randomized to receive pulsed accelerated 365-nm ultraviolet-A illumination in a central annular zone of 4.0 mm (1 second on, 1 second off; 30 mW/cm2 ), and the fellow eye in a 3.5 mm annular zone (0.5 second on, 1 second off; 45 mW/cm2 ). Uncorrected distance visual acuity (UDVA), MRSE, low-contrast visual acuity (LCVA), best spectacle corrected visual acuity (BSCVA), endothelial cell count (ECC) and Scheimpflug light scattering depths were assessed through 24-month follow-up. RESULTS Twenty-seven participants (54 eyes) were included. The 3.5 mm protocol rendered less subjective ocular discomfort posttreatment and a larger improvement than the 4.0 mm protocol in UDVA: -0.52 (-0.72, -0.32) logMAR (medians and interquartile ranges, IQR) and -0.38 (-0.50, -0.22), p = 0.003 and MRSE: +1.25 D (0.75, 1.50) and +1.0 (0.75, 1.0), p = 0.037. The transient reduction in LCVA was larger with the 3.5 mm protocol (p < 0.01). No adverse events, and no reductions in ECC or BSCVA were noted. CONCLUSION Epi-on PiXL in high oxygen reduces myopia in healthy eyes. A larger reduction of myopia and less early posttreatment subjective ocular discomfort can be seen with a smaller treatment zone, but likely at the expense of a transient decrease in low-contrast visual acuity.
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Affiliation(s)
- Sofie Näslund
- Department of Clinical Science/Ophthalmology Umeå University Umeå Sweden
| | | | - Anneli Fredriksson
- Department of Clinical Science/Ophthalmology Umeå University Umeå Sweden
| | - Anders Behndig
- Department of Clinical Science/Ophthalmology Umeå University Umeå Sweden
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Adverse events after riboflavin/UV-A corneal cross-linking: a literature review. Int Ophthalmol 2021; 42:337-348. [PMID: 34448966 DOI: 10.1007/s10792-021-02019-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 08/12/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND Riboflavin/UV-A corneal cross-linking (CXL) for treating keratoconus and iatrogenic corneal ectasia has been well-established as first treatment option to stabilize corneal tissue biomechanical instability. Although the plethora of clinical studies has been published into the field, there is no systematic review assessing the type and frequency of adverse events after CXL. METHODS A systemic literature review on clinical safety and adverse events after CXL in patients with keratoconus and corneal ectasia was performed using PubMed. A literature search was performed for relevant peer-reviewed publications. The main outcome measures extracted from the articles were adverse events, endothelial cell density, corrected distance visual acuity and maximum simulated keratometry. RESULTS The most frequent adverse events after CXL were corneal haze and corneal edema, which were mild and transient. The severe adverse events were infrequent (cumulative incidence: < 1.3%) after CXL. The clinical benefits of CXL highly outweighed the risks for the treatment of keratoconus and corneal ectasia. CONCLUSIONS The severe adverse events with permanent sequelae are infrequent after CXL and all are associated with corneal de-epithelialization, such as infectious keratitis and corneal scarring.
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Management of small-incision lenticule extraction ectasia using tissue addition and pocket crosslinking. J Cataract Refract Surg 2021; 47:407-412. [PMID: 32694305 DOI: 10.1097/j.jcrs.0000000000000335] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 06/17/2020] [Indexed: 10/23/2022]
Abstract
The feasibility of managing ectasia after small-incision lenticule extraction (SMILE) using tissue addition and pocket corneal crosslinking (CXL) is described. Four eyes of 3 patients (mean age 25.7 years) developed features of keraectasia at a mean period of 3 years after SMILE for myopia. All cases were managed with insertion of heterologous SMILE lenticules in the previously created pocket, followed by simultaneous accelerated CXL. At a mean follow-up of 7.67 months, there was improvement in corrected distance visual acuity and reduction in keratometry and higher-order aberrations in all eyes. The visual, refractive, and topographic parameters remained stable at the last visit compared with the 2-week follow-up visit. No eye developed haze, infection, or rejection requiring tissue explantation. Early experience showed tissue addition with simultaneous pocket CXL to be a feasible approach for managing ectasia after SMILE. However, further follow-up is required to establish the long-term safety and effects on corneal stabilization.
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Gilevska F, Biscevic A, Popovic Suic S, Bohac M, Patel S. Are changes in visual acuity and astigmatism after corneal cross-linking (CXL) in keratoconus predictable? Graefes Arch Clin Exp Ophthalmol 2021; 259:2259-2268. [PMID: 33885984 DOI: 10.1007/s00417-021-05173-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 03/05/2021] [Accepted: 03/22/2021] [Indexed: 10/21/2022] Open
Abstract
PURPOSE To evaluate changes in corrected distance visual acuity (CDVA), ratio of anterior and posterior corneal radii over the thinnest region of the cornea (ARC/PRC), and astigmatism after cross-linking (CXL) in keratoconus. METHODS Subjective refraction and ARC/PRC (using Pentacam™) were monitored over 1 year in (I) keratoconus treated with routine CXL (n = 53), (II) relatively stable keratoconus (n = 23), and (III) age/gender matched controls (n = 24). RESULTS CDVA (median, mode, interquartile range) improved significantly in group I, compared with groups II and III (p < 0.05), from 0.45 (0.60, 0.20-0.63) to 0.80 (0.95, 0.60-0.95); change in CDVA was associated with preop CDVA (p < 0.01 at all times postop). ARC/PRC (mean ± sd, 95% CI) changed from 1.362 (± 0.048, 1.347-1.377) to 1.425 (± 0.073, 1.401-1.449). CDVA and ARC/PRC remained stable in II and III. Significant relationships were revealed between logCDVA and ARC/PRC in I and II (at 12 months, I rs = - 0.464, II rs - 0.449) and logCDVA at postop(y), log CDVA at preop(x1), and ARC/PRC at preop(x2) in I (at 12 months, y = 0.356x1 - 1.312x2 + 1.806, r21 = 0.494, r22 = 0.203). Astigmatic power (mean ± sd, 95% CI) improved from - 3.10DC (± 1.52, - 3.55 to - 2.66) to - 2.53DC (± 1.24, - 2.90 to - 2.17) in I, and worsened from - 1.27DC (± 1.32, - 1.81 to - 0.73) to - 1.61DC (± 1.28, - 2.13 to - 1.09) in II. Vector analysis revealed in group I (a) the power of the surgically induced astigmatism (SIA) was linked to astigmatic power at preop and (b) the difference between the axis of astigmatism at preop(ø) and the axis of the SIA was linked to ø. CONCLUSION CXL improved CDVA, increased the ARC/PRC ratio, and modified the association between CDVA and ARC/PRC. The change in CDVA was linked to preop CDVA and ARC/PRC values. The association between SIA and preop astigmatism implies there is not a simple cause and effect relationship with CXL.
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Affiliation(s)
- Fanka Gilevska
- Eye Clinic Sistina Oftalmologija, Skupi 5A, Skopje, Republic of North Macedonia.
| | | | | | - Maja Bohac
- Specialty Eye Hospital "Svjetlost", Zagreb, Croatia.,School of Medicine, University of Rijeka, Rijeka, Croatia
| | - Sudi Patel
- Specialty Eye Hospital "Svjetlost", Zagreb, Croatia
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Hayes S, Morgan SR, Meek KM. Keratoconus: cross-linking the window of the eye. THERAPEUTIC ADVANCES IN RARE DISEASE 2021; 2:26330040211003573. [PMID: 37181107 PMCID: PMC10032441 DOI: 10.1177/26330040211003573] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 02/25/2021] [Indexed: 05/16/2023]
Abstract
Keratoconus is a condition in which the cornea progressively thins and weakens, leading to severe, irregular astigmatism and a significant reduction in quality of life. Although the precise cause of keratoconus is still not known, biochemical and structural studies indicate that overactive enzymes within the cornea break down the constituent proteins (collagen and proteoglycans) and cause the tissue to weaken. As the disease develops, collagen fibres slip past each other and are redistributed across the cornea, causing it to change shape. In recent years, it was discovered that the photochemical induction of cross-links within the corneal extracellular matrix, through the use of riboflavin and ultraviolet (UVA) light, could increase the strength and enzymatic resistance of the tissue and thereby halt keratoconus progression. Worldwide acceptance and use of riboflavin/UVA corneal cross-linking therapy for halting keratoconus progression has increased rapidly, in accordance with the growing body of evidence supporting its long-term effectiveness. This review focusses on the inception of riboflavin/UVA corneal cross-linking therapy for keratoconus, its clinical effectiveness and the latest scientific advances aimed at reducing patient treatment time, improving patient comfort and increasing patient eligibility for treatment. Plain language summary Review of current treatments using cross-linking to halt the progress of keratoconus Keratoconus is a disease in which the curved cornea, the transparent window at the front of the eye, weakens, bulges forward into a cone-shape and becomes thinner. This change of curvature means that light is not focussed onto the retina correctly and vision is progressively impaired. Traditionally, the effects of early keratoconus were alleviated by using glasses, specialist contact lenses, rings inserted into the cornea and in severe cases, by performing a corneal transplant. However, it was discovered that by inducing chemical bonds called cross-links within the cornea, the tissue could be strengthened and further thinning and shape changes prevented. The standard cross-linking procedure takes over an hour to perform and involves the removal of the cells at the front of the cornea, followed by the application of Vitamin B2 eye drops and low energy ultraviolet light (UVA) to create new cross-links within the tissue. Clinical trials have shown this standard procedure to be safe and effective at halting keratoconus progression. However, there are many treatment modifications currently under investigation that aim to reduce patient treatment time and increase comfort, such as accelerated cross-linking procedures and protocols that do not require removal of the surface cells. This review describes the different techniques being developed to carry out corneal cross-linking efficiently and painlessly, to halt keratoconus progression and avoid the need for expensive surgery.
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Affiliation(s)
- Sally Hayes
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ. UK
| | - Siân R Morgan
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK
| | - Keith M Meek
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK
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Toro-Giraldo L, Morales Flores N, Santana-Cruz O, Ramirez-Miranda A, Navas A, Olivo-Payne A, Lichtinger A, Jimenez-Corona A, Graue-Hernández EO. Cool Crosslinking: Riboflavin at 4°C for Pain Management After Crosslinking for Keratoconus Patients, A Randomized Clinical Trial. Cornea 2021; 40:1-4. [PMID: 33264161 DOI: 10.1097/ico.0000000000002484] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To explore corneal cooling as a method of pain management in corneal-accelerated collagen cross-linking. METHODS This was a prospective and interventional randomized clinical trial registered in the National Institutes of Health Clinical Trials through the identifier NCT030760770. The research was conducted at the Institute of Ophthalmology "Conde de Valenciana." A total of 98 patients were randomly assigned to one of the following 2 groups: cold riboflavin (4°C) group or control group (riboflavin at room temperature). The inclusion criteria were patients of any sex, older than 18 years of age with keratoconus diagnosis who needed management with cross-linking in both eyes because of the evidence of progression. The exclusion criteria were patients who had cross-linking without epithelial debridement, unilateral cross-linking, or any other ocular pathologies besides keratoconus and any cognitive incapacity that would make the understanding of the pain test difficult. The main outcome measures were pain, tearing, photophobia, foreign body sensation, and irritation. RESULTS At 2 hours post-op, pain in the case and control groups was 3.80 ± 3.00 and 8.08 ± 2.21 (P < 0.05), tearing was 1.56 ± 1.96 and 8.29 ± 2.42 (P < 0.05), photophobia was 5.44 ± 3.57 and 7.83 ± 2.64 (P < 0.05), foreign body sensation was 2.20 ± 2.78 and 6.54 ± 2.73 (P < 0.05), and irritation was 3.48 ± 2.98 and 6.79 ± 3.00 (P < 0.05), respectively. A statistical significant difference was maintained in pain values on day 1 (2.79 ± 3.09 and 4.91 ± 3.27 [P < 0.05]), 2 (2.54 ± 2.41 and 4.00 ± 2.43 [P < 0.05]), and 4 (0.45 ± 0.76 and 1.22 ± 1.67 [P < 0.05]). CONCLUSIONS This study demonstrated that pain and associated symptoms decreased significantly in the riboflavin 4°C group.
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Affiliation(s)
- Laura Toro-Giraldo
- Department of Cornea, External Disease and Refractive Surgery, Institute of Ophthalmology "Conde de Valenciana," Mexico City, Mexico
| | - Norma Morales Flores
- Department of Cornea, External Disease and Refractive Surgery, Institute of Ophthalmology "Conde de Valenciana," Mexico City, Mexico
| | - Omar Santana-Cruz
- Department of Optometry, Institute of Ophthalmology "Conde de Valenciana," Mexico City, Mexico; and
| | - Arturo Ramirez-Miranda
- Department of Cornea, External Disease and Refractive Surgery, Institute of Ophthalmology "Conde de Valenciana," Mexico City, Mexico
| | - Alejandro Navas
- Department of Cornea, External Disease and Refractive Surgery, Institute of Ophthalmology "Conde de Valenciana," Mexico City, Mexico
| | - Andrew Olivo-Payne
- Department of Cornea, External Disease and Refractive Surgery, Institute of Ophthalmology "Conde de Valenciana," Mexico City, Mexico
| | - Alejandro Lichtinger
- Department of Cornea, External Disease and Refractive Surgery, Institute of Ophthalmology "Conde de Valenciana," Mexico City, Mexico
| | - Aida Jimenez-Corona
- Department of Ocular Epidemiology and Public Health, Institute of Ophthalmology "Conde de Valenciana," Mexico City, Mexico
| | - Enrique O Graue-Hernández
- Department of Cornea, External Disease and Refractive Surgery, Institute of Ophthalmology "Conde de Valenciana," Mexico City, Mexico
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Badawi A. Corneal haze and densitometry in keratoconus after collagen cross-linking by three different protocols. J Curr Ophthalmol 2021; 33:422-430. [PMID: 35128189 PMCID: PMC8772486 DOI: 10.4103/joco.joco_145_21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 06/06/2021] [Accepted: 06/06/2021] [Indexed: 11/04/2022] Open
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Comparative Results of "Epi-Off" Conventional versus "Epi-Off" Accelerated Cross-Linking Procedure at 5-year Follow-Up. J Ophthalmol 2020; 2020:4745101. [PMID: 32774904 PMCID: PMC7396097 DOI: 10.1155/2020/4745101] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 06/22/2020] [Indexed: 01/08/2023] Open
Abstract
Purpose The aim of our study was to compare the long-term efficacy and safety of “epi-off” conventional and “epi-off” accelerated corneal cross-linking (CXL) in patients with progressive keratoconus. Methods “Epithelial-off” (“Epi-off”) CXL using the conventional technique (3 mW/cm2, 30 minutes) was performed in 93 eyes of 93 patients (S-CXL group) and “epi-off” accelerated method (9 mW/cm2, 10 minutes) in 76 eyes of 76 patients with progressive KCN (A-CXL group). Cases with different stages of keratoconus and topographic evidence of progression were included. Main outcomes comprised refraction, keratometry measurements, uncorrected (UCVA) and best-corrected visual acuity (BCVA), and topographical indices. Micromorphological analysis was assessed by anterior segment ocular coherence tomography (AS-OCT). The follow-up period was 5 years. Results In both groups, Kflat presented similar results: decrease at 1 year (p=0.465), at 2 years (p=0.672), at 3 years (p=0.198), at 4 years (p=0.32), and at 5 years (p=0.864). In both groups, Ksteep presented a similar decrease at 1 year (p=0.709), at 2 years (p=0.455), at 3 years (p=0.43), at 4 years (p=0.57), and at 5 years (p=0.494), with no statistically significant difference. Decrease in Kavg was similar in both groups at all analyzed time points (p=0.18 at 1 year, p=0.093 at 2 years, p=0.57 at 3 years, p=0.154 at 4 years, and p=0.247 at 5 years). Kmax had a similar decrease in both groups at 1 year (p=0.06), at 2 years (p=0.09), at 3 years (p=0.126), at 4 years (p=0.113), and at 5 years (p=0.114). There was no statistically significant difference between the cylinder decrease in both groups (p=0.349 at 1 year, p=0.6782 at 2 years, p=0.299 at 3 years, p=0.0943 at 4 years, and p=0.144 at 5 years). The BCVA values were statistically significantly higher than the preoperative values in both groups at all time points (p < 0.05). Topographical indices such as thinnest corneal point (TP), corneal volume (CV), index vertical asymmetry (IVA), index of vertical asymmetry (ISV), index of height asymmetry (IHA), index of height decentration (IHD), Belin/Ambrosio Enhanced Ectasia Display (BAD_D), and Ambrosio retinal thickness (ART Max) were significantly statistically decreased compared with baseline at all time points, in both groups. Conclusion “Epi-off” accelerated and conventional CXL have the same efficacy in terms of improvement in visual and topographic outcomes.
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Abdel-Radi M, Eldaly Z, Abdelmotaal H, Abdelrahman R, Sayed M, Soliman K. Correlation between corneal demarcation line depth in epithelium-off and trans-epithelium accelerated corneal cross linking and keratoconus progression. Int J Ophthalmol 2020; 13:907-912. [PMID: 32566501 DOI: 10.18240/ijo.2020.06.08] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Accepted: 10/08/2019] [Indexed: 02/05/2023] Open
Abstract
AIM To compare corneal demarcation line (DL) depth in both accelerated epithelium-off and trans-epithelium cross linking (CXL) using anterior segment optical coherence tomography (AS-OCT) and its relation to maximum keratometry (Kmax) progression in both techniques. METHODS A prospective comparative interventional study where patients with mild to moderate keratoconus (KC) were classified into two groups: accelerated epithelium-off and trans-epithelium CXL based on corneal pachymetry. Assessment of corneal DL depth was carried out after 3mo by AS-OCT. Kmax readings were evaluated after one year follow up using the Scheimpflug imaging system. RESULTS Study included 74 eyes of 44 patients. Group A underwent epithelium-off CXL (41 eyes), while Group B underwent trans-epithelium CXL (33 eyes). At 3mo follow up, mean corneal DL depth in Group A was 219.9±58.4 µm while in Group B was 127.2±7.8 µm (P<0.05). The mean Kmax changed from 51.9±3.9 to 51.3±4.2 diopters in Group A and from 53.1±4.1 to 53.6±5 diopters in Group B with insignificant difference in Kmax changes in either group (P>0.05). In addition, no significant change in corneal pachymetry was found in both groups (mean change at 1y: 6.4±4.7 and -10.1±2.3 µm in Groups A and B respectively). CONCLUSION Despite a significantly deeper corneal DL depth created by accelerated epithelium-off CXL technique compared to accelerated trans-epithelium CXL, there is no significant impact on keratoconus progression.
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Affiliation(s)
| | - Zeiad Eldaly
- Department of Ophthalmology, Assiut University, Assiut 71516, Egypt
| | | | | | - Mohamed Sayed
- Department of Ophthalmology, Assiut University, Assiut 71516, Egypt
| | - Kamel Soliman
- Department of Ophthalmology, Assiut University, Assiut 71516, Egypt
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Photorefractive intrastromal crosslinking for correction of hyperopia: 12-month results. J Cataract Refract Surg 2020; 46:434-440. [DOI: 10.1097/j.jcrs.0000000000000074] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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21
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Ma J, Wang Y, Jhanji V. Corneal refractive surgery combined with simultaneous corneal cross-linking: Indications, protocols and clinical outcomes-A review. Clin Exp Ophthalmol 2019; 48:78-88. [PMID: 31487097 DOI: 10.1111/ceo.13621] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Revised: 08/26/2019] [Accepted: 09/02/2019] [Indexed: 12/25/2022]
Abstract
Corneal refractive surgery is one of the most common approaches for correction of refractive errors. Combined corneal refractive surgery and corneal cross-linking (CXL) has been proposed as a method to achieve better refractive stability and to prevent iatrogenic corneal ectasia. However, there are concerns regarding its indications, surgical safety, standardization of protocols and long-term effect on corneal tissue. This review article aims to discuss the current knowledge and recent updates on combination of CXL and refractive surgery.
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Affiliation(s)
- Jiaonan Ma
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
| | - Yan Wang
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China.,College of Ophthalmology, Tianjin Medical University, Tianjin Eye Hospital, Tianjin Eye Institute, Tianjin Key Lab of Ophthalmology and Visual Science, Nankai University Affiliated Eye Hospital, Tianjin, China
| | - Vishal Jhanji
- UPMC Eye Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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Hernandez-Camarena JC, Graue-Hernandez EO, Loya-García D, Ruiz-Lozano RE, Valdez-García JE. Correlation between corneal stromal demarcation line depth and topographic outcomes after two pulsed-light-accelerated crosslinking protocols. Clin Ophthalmol 2019; 13:1665-1673. [PMID: 31507315 PMCID: PMC6720021 DOI: 10.2147/opth.s206103] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 04/24/2019] [Indexed: 11/23/2022] Open
Abstract
Purpose To report the visual and topographic outcomes of two pulsed-light-accelerated CXL (A-CXL) protocols at a 12-month follow-up and their correlation with the corneal stromal demarcation line (DL) depth. Patients and methods Retrospective comparative cohort of patients with documented progressive keratoconus were included. Two epi-off pulsed-light [1s on–1s off] A-CXL protocols were compared: irradiance 30*8 and 45*5:20 (fluence 7.2 J/cm2). UDVA, CDVA, spherical equivalent (SE), topographic astigmatism, Kmin, Kmax, Km, central corneal thickness (CCT), thinnest pachymetry (TCT) and endothelial cell density (ECD) were measured preoperatively and months 1, 3, 6 and 12 postoperative. Corneal DL was measured 1 month postoperatively using anterior segment optical coherence tomography. Results Fifty eyes (27 patients): 22 eyes in group A-CXL (30*8), 28 eyes in group A-CXL (45*5:20). Mean age (years) was 19.04±4.71 and 20.32±4.57. DL depth (µm) at month 1 was 200.63±10.01 µm and 184.53±19.68 µm for group A-CXL (30*8) and group A-CXL (45*5:20), respectively (p<0.001). Significant improvement in CDVA, topographic astigmatism, Kmin, Kmax and Km was observed in both groups (no significant difference between groups) and no significant changes were observed in CCT, TCT and ECD with regard to baseline. Over 85% of the eyes in both protocols achieved stabilization or improvement in maximum K at the end of the follow-up. No significant correlations between DL and any visual or topographic outcomes were observed at 12 months. Conclusion No correlation between DL depth and visual or topographic outcomes was observed on either protocol. Although significant improvement on CDVA, topographic astigmatism, Kmin, Kmax and Km was observed in both groups at 12 months, further research is needed to assure safety and effectiveness at stabilizing keratoconus progression.
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Affiliation(s)
| | - Enrique O Graue-Hernandez
- Department of Cornea and Refractive Surgery, Institute of Ophthalmology Conde de Valenciana, Mexico City, Mexico
| | - Denise Loya-García
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, NL 64710, Mexico
| | - Raul E Ruiz-Lozano
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, NL 64710, Mexico
| | - Jorge E Valdez-García
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, NL 64710, Mexico
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Pantalon A, Pfister M, Aranha dos Santos V, Sapeta S, Unterhuber A, Pircher N, Schmidinger G, Garhöfer G, Schmidl D, Schmetterer L, Werkmeister RM. Ultrahigh-resolution anterior segment optical coherence tomography for analysis of corneal microarchitecture during wound healing. Acta Ophthalmol 2019; 97:e761-e771. [PMID: 30762310 PMCID: PMC6767559 DOI: 10.1111/aos.14053] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 01/19/2019] [Indexed: 12/29/2022]
Abstract
PURPOSE To employ ultrahigh-resolution (UHR) optical coherence tomography (OCT) for investigation of the early wound healing process in corneal epithelium. METHODS A custom-built UHR-OCT system assessed epithelial healing in human keratoconic cornea after epi-off crosslinking (CXL) procedure and a wound healing model in rabbits with iatrogenic corneal injury. 3D OCT data sets enhanced obtaining epithelial thickness maps and evaluation of reepithelization stage. Accompanying changes in deeper corneal microarchitecture were analysed. RESULTS The mean central corneal thickness in 40 eyes with keratoconus at baseline was 482.7 ± 38.2 μm, while mean central epithelial thickness (CET) was 43.8 ± 6.4 μm. At the final visit 20 ± 5 days post-CXL procedure, CET was 35.0 ± 5.8 μm, significantly thinner after reepithelization (p < 0.001). Surgical success was assessed at the final visit through the demarcation line (DL), identified at 43.7 ± 13.5% stromal depth. In rabbits, the mean CET in 20 eyes at baseline was 35.9 ± 2.6 μm. In rabbits that revealed complete wound closure (10/20 eyes) at the last study day at 72 hr, CET was significantly thinner compared to baseline (30.4 ± 2.8 μm versus 35.4 ± 2.9 μm, p = 0.005). An intra-stromal landmark indicating early keratocyte apoptosis was measured at 30.0 ± 5.1% stromal depth. Epithelial thickness maps showed the time-course of corneal healing. CONCLUSION Ultrahigh-resolution (UHR)-OCT provided precise assessment of epithelial wound and its healing by 3D-mapping. In addition, microarchitectural changes in the cornea in early phases of epithelial healing were revealed.
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Affiliation(s)
- Anca Pantalon
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
- Department of OphthalmologyGr. T. Popa University of Medicine and PharmacyIasiRomania
| | - Martin Pfister
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
- Christian Doppler Laboratory for Ocular and Dermal Effects of ThiomersMedical University of ViennaViennaAustria
| | | | - Sabina Sapeta
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
| | - Angelika Unterhuber
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
| | - Niklas Pircher
- Department of OphthalmologyMedical University of ViennaViennaAustria
| | | | - Gerhard Garhöfer
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria
| | - Doreen Schmidl
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria
| | - Leopold Schmetterer
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
- Christian Doppler Laboratory for Ocular and Dermal Effects of ThiomersMedical University of ViennaViennaAustria
- Singapore Eye Research InstituteSingapore National Eye CentreSingaporeSingapore
- Ophthalmology and Visual Sciences Academic Clinical ProgramDuke‐NUS Medical SchoolSingaporeSingapore
- Ophthalmic Engineering & Innovation LaboratoryDepartment of Biomedical EngineeringFaculty of EngineeringNational University of SingaporeSingaporeSingapore
- Lee Kong Chian School of MedicineNanyang Technological UniversitySingaporeSingapore
| | - René M. Werkmeister
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
- Christian Doppler Laboratory for Ocular and Dermal Effects of ThiomersMedical University of ViennaViennaAustria
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Abstract
PURPOSE There has been a recent explosion in the variety of techniques used to accomplish corneal cross-linking (CXL) for the treatment of ectatic corneal diseases. To understand the success or failure of various techniques, we review the physicochemical basis of corneal CXL and re-evaluate the current principles and long-standing conventional wisdom in the light of recent, compelling, and sometimes contradictory research. METHODS Two clinicians and a medicinal chemist developed a list of current key topics, controversies, and questions in the field of corneal CXL based on information from current literature, medical conferences, and discussions with international practitioners of CXL. RESULTS Standard corneal CXL with removal of the corneal epithelium is a safe and efficacious procedure for the treatment of corneal ectasias. However, the necessity of epithelium removal is painful for patients, involves risk and requires significant recovery time. Attempts to move to transepithelial corneal CXL have been hindered by the lack of a coherent understanding of the physicochemistry of corneal CXL. Misconceptions about the applicability of the Bunsen-Roscoe law of reciprocity and the Lambert-Beer law in CXL hamper the ability to predict the effect of ultraviolet A energy during CXL. Improved understanding of CXL may also expand the treatment group for corneal ectasia to those with thinner corneas. Finally, it is essential to understand the role of oxygen in successful CXL. CONCLUSIONS Improved understanding of the complex interactions of riboflavin, ultraviolet A energy and oxygen in corneal CXL may provide a successful route to transepithelial corneal CXL.
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Vinciguerra R, Tzamalis A, Romano V, Arbabi EM, Batterbury M, Kaye SB. Assessment of the Association Between In Vivo Corneal Biomechanical Changes After Corneal Cross-linking and Depth of Demarcation Line. J Refract Surg 2019; 35:202-206. [PMID: 30855098 DOI: 10.3928/1081597x-20190124-01] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 01/18/2019] [Indexed: 11/20/2022]
Abstract
PURPOSE To test for an association between stiffening following corneal cross-linking (CXL) and demarcation line depth. METHODS Sixty-six eyes of 66 patients treated with CXL for progressive keratoconus were included. Dynamic corneal response parameters (DCRs) were measured with the Corvis ST (Oculus Optikgeräte GmbH; Wetzlar, Germany) on the day of CXL and after 1 month. Demarcation line was measured 4 weeks after CXL. A multivariate general linear model was used to test for an association between the change in DCRs and the ratio between demarcation line depth and the postoperative pachymetry. RESULTS The authors found no significant associations between the change in inverse concave integrated radius (1/R) and the demarcation line ratio (P = .46), age (P = .33), sex (P = .11), preoperative maximum keratometry (P = .10), and laterality (P = .82). Similarly, there was no significant correlation between the change in 1/R and the demarcation line ratio (R2 = .002 and P = .75). However, there was a significant association between the preoperative values of 1/R and the respective change in 1/R (P < .0001). The change in 1/R was inversely proportional to the patient's preoperative 1/R; stiffer corneas (lower values of 1/R) were less affected than less stiff corneas (R2 = .23, P < .0001). CONCLUSIONS CXL is associated with changes in DCRs, suggesting a change in corneal biomechanics following CXL. These changes do not appear to be associated with the demarcation line depth. [J Refract Surg. 2019;35(3):202-206.].
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Thorsrud A, Hagem AM, Sandvik GF, Drolsum L. Superior outcome of corneal collagen cross-linking using riboflavin with methylcellulose than riboflavin with dextran as the main supplement. Acta Ophthalmol 2019; 97:415-421. [PMID: 30284383 DOI: 10.1111/aos.13928] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 04/22/2018] [Indexed: 11/27/2022]
Abstract
PURPOSE To compare the effect of corneal collagen cross-linking (CXL) on progressive keratoconus using 0.1% riboflavin with either dextran or methylcellulose as the main supplement. METHODS In a comparative case series, CXL was performed in 40 patients (40 eyes) using a riboflavin solution containing either dextran (dextran-riboflavin; n = 20) or methylcellulose (methylcellulose-riboflavin; n = 20). Changes in central corneal thickness (CCT), Scheimpflug tomography, maximal keratometry reading (Kmax ), visual acuity (VA) and endothelial cell density (ECD) were recorded. Stromal changes one month after surgery were analysed using optical coherence tomography (OCT) and in vivo confocal microscopy (IVCM). RESULTS The CCT was significantly higher in the methylcellulose-riboflavin group during the CXL procedure. The IVCM demarcation line depth was 274 ± 80 (SD) μm in the dextran-riboflavin group and 442 ± 80 μm in the methylcellulose-riboflavin group (p < 0.001). Complete absence of keratocytes in the pre-endothelial stroma was found in none of the corneas treated with dextran-riboflavin and in 42% of the corneas treated with methylcellulose-riboflavin. Visibility of the OCT demarcation line was significantly lower in the methylcellulose-riboflavin group. Kmax and corrected distance visual acuity were improved in the methylcellulose-riboflavin group and stable in the dextran-riboflavin group after 2 years. Endothelial cell density (ECD) was stable in both groups. CONCLUSION We found deeper structural changes in the methylcellulose-riboflavin group than in the dextran-riboflavin group. This may be explained by different riboflavin solution properties and raises safety concerns. The study also indicates improved effect using methylcellulose-riboflavin than dextran-riboflavin, possibly explained by deeper stromal CXL effect.
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Affiliation(s)
- Andreas Thorsrud
- Department of Ophthalmology Oslo University Hospital Oslo Norway
- Center for Eye Research University of Oslo Oslo Norway
| | - Anne Marie Hagem
- Department of Ophthalmology Oslo University Hospital Oslo Norway
- Center for Eye Research University of Oslo Oslo Norway
| | - Gunhild Falleth Sandvik
- Department of Ophthalmology Oslo University Hospital Oslo Norway
- Center for Eye Research University of Oslo Oslo Norway
| | - Liv Drolsum
- Department of Ophthalmology Oslo University Hospital Oslo Norway
- Center for Eye Research University of Oslo Oslo Norway
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Iqbal M, Elmassry A, Tawfik A, Elgharieb M, Nagy K, Soliman A, Saad H, Tawfik T, Ali O, Gad A, El Saman I, Radwan A, Elzembely H, Abou Ali A, Fawzy O. Standard cross-linking versus photorefractive keratectomy combined with accelerated cross-linking for keratoconus management: a comparative study. Acta Ophthalmol 2019; 97:e623-e631. [PMID: 30499232 PMCID: PMC6587973 DOI: 10.1111/aos.13986] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Purpose To compare the safety and efficacy of standard 30 min epithelium‐off cross‐linking (CXL) versus photorefractive keratectomy (PRK) combined with accelerated epithelium‐off cross‐linking (AXL) for the treatment of progressive keratoconus (CXL‐Plus). Methods This study was a prospective multicentre comparative clinical study. A total of 125 eyes of 75 patients with grade 1 keratoconus and documented progression were divided into two groups. Group A included 58 eyes treated with standard CXL. Group B included 67 eyes treated with combined PRK and AXL. The recorded data included UDVA, CDVA, subjective and objective refraction, keratometry and pachymetry using corneal topographies preoperatively and postoperatively at 3, 6, 12 and 24 months of follow‐up. Results In group A, at 24 months of UDVA and CDVA were improved from 1.12 ± 0.38 and 0.58 ± 0.42 to 0.66 ± 0.20 and 0.20 ± 0.12 (LogMAR±SD). The spherical equivalent was reduced from 4.03 ± 1.18 to 1.78 ± 1.04 D. The cylinder reduction was 0.32 ± 0.19 D. In group B, at 24 months of UDVA and CDVA were improved from 1.26 ± 0.52 and 0.68 ± 0.36 to 0.58 ± 0.28 and 0.20 ± 0.16 (LogMAR ± SD). The spherical equivalent was reduced from 4.23 ± 0.95 to 1.92 ± 0.74 D. The cylinder reduction was ±1.76 D. Conclusion Surprisingly, standard CXL showed close results to CXL‐Plus at the 24th follow‐up month. Standard CXL acted as a stabilizing procedure associated with a late myopic component reduction. CXL‐Plus acted as a refractive and stabilizing procedure with an early effect on both the myopic and the astigmatic component but no later improvements. Standard CXL seems to be more powerful than AXL in its long‐term effect. Therefore, in the future, we want to test the combination of PRK with standard CXL.
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Affiliation(s)
- Mohammed Iqbal
- Department of Ophthalmology Faculty of Medicine Sohag University Sohag Egypt
| | - Ahmed Elmassry
- Department of Ophthalmology Faculty of Medicine Alexandria University Alexandria Egypt
| | - Ahmed Tawfik
- Department of Ophthalmology Faculty of Medicine Zagazig University Zagazig Egypt
| | - Mervat Elgharieb
- Department of Ophthalmology Faculty of Medicine Suez Canal University Suez Egypt
| | - Khaled Nagy
- Department of Ophthalmology Faculty of Medicine Tanta University Tanta Egypt
| | - Ashraf Soliman
- Department of Ophthalmology Faculty of Medicine Ain Shams University Cairo Egypt
| | - Hisham Saad
- Department of Ophthalmology Faculty of Medicine Tanta University Tanta Egypt
| | - Tarek Tawfik
- Department of Ophthalmology Faculty of Medicine Benha University Benha Egypt
| | - Osama Ali
- Department of Ophthalmology Faculty of Medicine Sohag University Sohag Egypt
| | - Ahmed Gad
- Department of Ophthalmology Faculty of Medicine Sohag University Sohag Egypt
| | - Islam El Saman
- Department of Ophthalmology Faculty of Medicine Sohag University Sohag Egypt
| | - Alaa Radwan
- Department of Ophthalmology International Eye Clinic Cotoba EYE Center Cairo Egypt
| | - Hosam Elzembely
- Department of Ophthalmology Faculty of Medicine Minia University Minia Egypt
| | - Amin Abou Ali
- Department of Ophthalmology Faculty of Medicine Sohag University Sohag Egypt
| | - Omar Fawzy
- Department of Ophthalmology Sohag Eye Hospital Sohag Egypt
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10-Year Results of Standard Cross-Linking in Patients with Progressive Keratoconus in Romania. J Ophthalmol 2019; 2019:8285649. [PMID: 30984419 PMCID: PMC6431502 DOI: 10.1155/2019/8285649] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 01/25/2019] [Accepted: 02/04/2019] [Indexed: 11/17/2022] Open
Abstract
Purpose The purpose of the current study was to evaluate the long-term functional results based on keratometric measurements, spherical and cylinder equivalent in patients with progressive keratoconus treated with conventional "epi-off" corneal collagen cross-linking (CXL). Methods We conducted a retrospective study in which 113 eyes from 90 keratoconus-treated patients with CXL between 2006 and 2008 in Oculens Eye Clinic from Cluj-Napoca, Romania, were included. The diagnosis of keratoconus was based on corneal topography and its clinical signs. All patients were evaluated preoperatively, and a follow-up was performed at 1, 3, and 6 months and every year from 1 to 10 years after conventional CXL. Results All keratometry measurements improved significantly during the follow-up. Compared to preoperative values, the improvement of K max become statistically significant at 1 year after CXL (mean change compared to baseline -0.9 D, p < 0.001) and remained statistically significant thereafter up to 10 years (mean change compared to baseline -2.3 D, p < 0.001). As compared to preoperative values, mean spherical equivalent and mean cylinder improved during the follow-up, from a mean of -6.22 D before CXL to a mean value of -5.0 at 10 years, following CXL for spherical equivalent and from -4.4 D at baseline to -3.4 D at 10 years for cylinder (p < 0.05 for both). Uncorrected visual acuity increased, remaining statistically significant, by 0.104 logMAR at 10 years after CXL (p=0.0015), and best-corrected visual acuity increased by 0.135 logMAR at 10 years after CXL (p=0.015). We did not observe any case of severe complication. Conclusion Our results show that CXL has a favorable effect on the progression of KC. The reduced K values, cylinder and spherical equivalent, and increased visual acuity remained the same 10 years after the procedure.
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Cagini C, Di Lascio G, Messina M, Riccitelli F, Dua HS. Correlation of central and peripheral keratometric parameters after corneal collagen cross-linking in keratoconus patients. Int Ophthalmol 2018; 39:2041-2048. [PMID: 30421316 DOI: 10.1007/s10792-018-1041-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 11/07/2018] [Indexed: 02/06/2023]
Abstract
PURPOSE To evaluate the difference in the central and peripheral keratometric parameters in patients with keratoconus after corneal collagen cross-linking (CXL). METHODS Forty-eight eyes of 32 patients (18 males, 16-28 years) affected by progressive keratoconus in different stages of evolution underwent CXL using the standard epithelium-off protocol. Corneal thickness and corneal curvature before CXL and after 6 and 12 months using the Sirius tomographer were analyzed. The values of the mean corneal thickness at the corneal apex (CAT), center of the pupil (PCT), thinnest point (CTTL) and along concentric circles of 2, 4, 6, 8, 8.5, 9, 9.5 and 10 mm diameter were evaluated; the values of the mean curvature at the corneal apex and at the points in which the inferior, superior, nasal and temporal meridians crossed the above-mentioned concentric circles were also evaluated. RESULTS The mean preoperative values for CAT, PCT and CTTL were 461.4 ± 30.3, 475.3 ± 30.5 and 441 ± 32.0, respectively. The values after 12 months of CXL were 444.6 ± 36.2, 451.6 ± 36.7 and 418.2 ± 41.4. The peripheral corneal thickness at the eight points ranged from 479 to 733 preoperatively. At 12-month post-CXL, the values ranged from 444.6 to 734.1. The mean posterior curvature from apex to periphery ranged from - 4.5 to - 9.1 days preoperatively and from - 4.5 to - 9.2 days at 12 months. These were not statistically significant (ANOVA and unpaired T test). CONCLUSIONS Our data suggest that CXL over an 8-mm zone can stabilize the peripheral cornea. Longer-term follow-up studies on the peripheral cornea after CXL will provide useful information.
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Affiliation(s)
- C Cagini
- Ophthalmology Section, Department of Biomedical and Surgical Sciences, S. Maria della Misericordia Hospital, University of Perugia, Piazza Menghini 1, S. Andrea delle Fratte, 06156, Perugia, Italy.
| | - G Di Lascio
- Ophthalmology Section, Department of Biomedical and Surgical Sciences, S. Maria della Misericordia Hospital, University of Perugia, Piazza Menghini 1, S. Andrea delle Fratte, 06156, Perugia, Italy
| | - M Messina
- Ophthalmology Section, Department of Biomedical and Surgical Sciences, S. Maria della Misericordia Hospital, University of Perugia, Piazza Menghini 1, S. Andrea delle Fratte, 06156, Perugia, Italy
- Section of Academic Ophthalmology, Division of Clinical Neuroscience, Nottingham University Hospitals NHS Trust, University of Nottingham, Nottingham, UK
| | - F Riccitelli
- Ophthalmology Section, Department of Biomedical and Surgical Sciences, S. Maria della Misericordia Hospital, University of Perugia, Piazza Menghini 1, S. Andrea delle Fratte, 06156, Perugia, Italy
| | - H S Dua
- Section of Academic Ophthalmology, Division of Clinical Neuroscience, Nottingham University Hospitals NHS Trust, University of Nottingham, Nottingham, UK
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Belin MW, Lim L, Rajpal RK, Hafezi F, Gomes JAP, Cochener B. Corneal Cross-Linking: Current USA Status: Report From the Cornea Society. Cornea 2018; 37:1218-1225. [PMID: 30067537 DOI: 10.1097/ico.0000000000001707] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The initial published clinical report on riboflavin/ultraviolet A corneal cross-linking (CXL) for treatment of progressive keratoconus dates back to 2003. CXL has since then been widely used outside the United States for treatment of progressive keratoconus and post-laser in situ keratomileusis ectasia. The Food and Drug Administration (FDA) approved Avedro Inc.'s corneal cross-linking system (KXL) for treatment of patients with progressive keratoconus and post-laser in situ keratomileusis ectasia in April 2016. The procedure is not currently approved for stable keratoconus. There are 2 FDA-approved topical ophthalmic solutions for use in CXL. Riboflavin 5'-phosphate in 20% dextran ophthalmic solution 0.146% (Photrexa Viscous) and Riboflavin 5'-phosphate ophthalmic solution 0.146% (Photrexa) are intended for use with the KXL system. Photrexa Viscous is used in all CXL procedures, whereas Photrexa is indicated for use when the corneal stroma is thinner than 400 µm after completion of the Photrexa Viscous induction period. The FDA-approved procedure using the Dresden protocol (UV-A, 3 mW/cm for 30 min) induces cytologic and morphologic changes in the anterior 250 to 300 µm of the corneal stroma. It has been believed that a minimum thickness of 400 μm was necessary to protect the corneal endothelium from potential damage. The CXL procedure using the standard Dresden protocol is established as the gold standard for treatment of progressive keratoconus. CXL treatment is indicated for a list of conditions ranging from corneal ectasia to infectious keratitis. Newer protocols, treatment regimens, and expanded indications will require further refinements, investigations, and long-term studies.
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Affiliation(s)
- Michael W Belin
- Department of Ophthalmology & Vision Science, University of Arizona, Tucson, AZ
| | - Li Lim
- Singapore National Eye Center, Singapore
| | - Rajesh K Rajpal
- Avedro Inc, Waltham, MA.,See Clearly Vision Group, Mclean, Virginia
| | | | - Jose A P Gomes
- Department of Ophthalmology and Visual Sciences, Federal University of Sao Paulo, Sao Paulo, Brazil
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Lin JT. Influencing Factors Relating the Demarcation Line Depth and Efficacy of Corneal Crosslinking. Invest Ophthalmol Vis Sci 2018; 59:5125-5126. [DOI: 10.1167/iovs.18-25244] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
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Wollensak G, Spörl E. Biomechanical efficacy of corneal cross-linking using hypoosmolar riboflavin solution. Eur J Ophthalmol 2018; 29:474-481. [DOI: 10.1177/1120672118801130] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Purpose: The use of hypoosmolar riboflavin solution has been suggested for cross-linking thin corneas. The aim of this study was to compare the biomechanical efficacy of corneal cross-linking using hypoosmolar dextran-free riboflavin solution (HCXL) versus isoosmolar standard corneal cross-linking treatment (CXL). Methods: A total of 24 postmortem porcine eyes with debrided corneas were subdivided into three treatment groups: Controls, the isoosmolar group with isoosmolar 0.1% riboflavin-20% dextran solution and the hypoosmolar group with dextran-free, 0.1% riboflavin solution. The samples were irradiated with UVA light of 365 nm wavelength and an irradiance of 3 mW/cm² for 30 min (dose 5.4 J/cm²). For the biomechanical measurements, 400-µm-deep anterior corneal flaps were created using a lamellar rotating microkeratome. Uniaxial stress–strain measurements were performed. Results: In the isoosmolar treatment group, stress and Young’s modulus at 8% strain were significantly increased by 67.97%, respectively, 62.62% versus the controls. In the hypoosmolar treatment group, stress and Young’s modulus at 8% strain were significantly increased by 81.21%, respectively, 51.40% versus the controls. There was no significant difference between the iso- and hypoosmolar groups in biomechanical efficacy. On histology, there was no edema in the anterior 200 µm of the corneas after stromal swelling by the hypoosmolar riboflavin solution. Conclusion: Corneal cross-linking using isoosmolar or hypoosmolar riboflavin solution induces a comparable biomechanical effect. This is explained by the localization of the maximum cross-linking effect in the anterior 200 µm of the cornea which are not affected by the swelling effect of hypoosmolar riboflavin solution.
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Affiliation(s)
| | - Eberhard Spörl
- Department of Ophthalmology, Technical University of Dresden, Dresden, Germany
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Visibility and Depth of the Stromal Demarcation Line After Corneal Collagen Cross-Linking Using Anterior Segment Optical Coherence Tomography: Comparison Between Isoosmolar and Hypoosmolar Riboflavin. Cornea 2018; 37:567-573. [PMID: 29300266 DOI: 10.1097/ico.0000000000001493] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE To evaluate and compare visibility and depth of the stromal demarcation line (DL) created after corneal collagen cross-linking (CXL) using anterior segment optical coherence tomography (AS-OCT) between 2 groups: CXL with isoosmolar and hypoosmolar riboflavin. METHODS In this retrospective study performed at Metz-Thionville Regional Hospital, consecutive patients with progressive keratoconus underwent CXL using an accelerated protocol (10 min, 9 mW/cm ultraviolet-A). AS-OCT (RS-3000, Nidek) was performed at 1 month after surgery, with stromal DL visibility graded. The corneal demarcation line depth (DLD) was also measured. RESULTS Seventy-five eyes of 58 patients with a mean age of 25.2 ± 9.1 years were enrolled in the study. Preoperative mean anterior Kmax was 57.4 ± 5.4 D. The mean thinnest pachymetry was 474.3 ± 35.7 μm. The mean depth of the stromal DL on 1-month optical coherence tomography evaluation was 331.2 ± 62.7 μm. A DL was visible (grades 1 and 2) in 54 (72%) treated eyes. A positive correlation was found between patient age and the DLD: deeper lines were found in older patients [r = 0.38, P = 0.005, confidence interval 95% (0.12; 0.58)]. Forty-one patients were included in the isoosmolar group and 34 in the hypoosmolar group: neither visibility nor DLD was significantly different between groups. The mean depth was 334.5 ± 67.5 μm and 328.1 ± 59.0 μm in the isoosmolar and hypoosmolar groups, respectively (P = 0.82). A DL was visible (grades 1 and 2) in 26 eyes (63.4%) and 28 eyes (82.4%) in the isoosmolar and hypoosmolar groups, respectively (P = 0.12). CONCLUSIONS The use of isoosmolar or hypoosmolar riboflavin does not significantly modify the depth or visibility of the stromal DL 1 month after accelerated CXL on AS-OCT evaluation.
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Vinciguerra R, Romano V, Arbabi EM, Brunner M, Willoughby CE, Batterbury M, Kaye SB. In Vivo Early Corneal Biomechanical Changes After Corneal Cross-linking in Patients With Progressive Keratoconus. J Refract Surg 2018; 33:840-846. [PMID: 29227513 DOI: 10.3928/1081597x-20170922-02] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Accepted: 08/25/2017] [Indexed: 11/20/2022]
Abstract
PURPOSE To report early corneal biomechanical changes after corneal cross-linking (CXL) in patients with keratoconus. METHODS Thirty-four eyes of 34 patients undergoing CXL for progressive keratoconus were included in this prospective clinical study. Dynamic corneal response (DCR) parameters obtained with the Corvis ST (OCULUS Optikgeräte GmbH; Wetzlar, Germany) were assessed at baseline (day of CXL) and after 1 month of follow-up; conversely, corneal tomography with the Pentacam (OCULUS Optikgeräte GmbH) was assessed at baseline and at 1, 3, and 6 months after CXL. RESULTS At the last follow-up visit (123.7 ± 69.6 days), all morphological parameters including steepest point (Kmax) and thinnest corneal thickness (ThCT) indicated stabilization of keratoconus (P > .05). Comparative analyses showed a rise of corneal stiffness demonstrated by a significant increase of Stiffness Parameter A1 (SP-A1) and Highest Concavity (SP-HC) and a significant decrease of Inverse Concave Radius (1/R) and Deformation Amplitude Ratio (DA Ratio) (P < .05). There was a significant correlation between the preoperative keratoconus characteristics (Kmax, Belin/Ambrósio final D value [BAD-D], and ThCT) and the DCR parameters (P < .05). Kmax and BAD-D showed a significant positive correlation with DA Ratio, Deflection Amplitude (DefA), and 1/R and a significant negative correlation with SPA1 and SP-HC. ThCT showed a significant positive correlation with SP-A1 and SP-HC and a significant negative correlation with DA Ratio, DefA, and 1/R. CONCLUSIONS This study suggests that the new DCR parameters of the Corvis ST are able to detect early changes in biomechanics following CXL and those that are measurable before corneal shape modifications take place. Based on these results, the authors suggest the use of these metrics to assess the early efficacy of cross-linking. [J Refract Surg. 2017;33(12):840-846.].
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