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Cehelyk EK, Syed ZA. Long-term outcomes of corneal crosslinking. Curr Opin Ophthalmol 2024; 35:315-321. [PMID: 38700950 DOI: 10.1097/icu.0000000000001054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2024]
Abstract
PURPOSE OF REVIEW This manuscript summarizes contemporary research from 2018 to 2023 evaluating long-term (≥2 years) outcomes of corneal crosslinking (CXL) for progressive keratoconus (KCN). RECENT FINDINGS The standard Dresden protocol (SDP) has been utilized clinically since the early 2000 s to treat ectatic disorders, primarily progressive KCN and postrefractive ectasia. Various modifications have since been introduced including accelerated and transepithelial protocols, which are aimed at improving outcomes or reducing complications. This review summarizes data demonstrating that the SDP halts disease progression and improves various visual and topographic indices (UDVA, CDVA, Kmax, K1, K2) up to 13 years postoperatively. Accelerated and transepithelial protocols have been found to be well tolerated alternatives to SDP with similar efficacy profiles. Studies focusing on pediatric populations identified overall higher progression rates after CXL. All protocols reviewed had excellent safety outcomes in adults and children. SUMMARY Recent studies revealed that SDP successfully stabilizes KCN long term, and a variety of newer protocols are also effective. Pediatric patients may exhibit higher progression rates after CXL. Further research is required to enhance the efficacy and ease of these protocols.
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Affiliation(s)
| | - Zeba A Syed
- Cornea Service, Wills Eye Hospital, Philadelphia, Pennsylvania, USA
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Omar Yousif M, Elkitkat RS, Hamza MN, Abdelsadek Alaarag N. Application of a Revised Tissue Saving Protocol for Combined Topography-Guided Photorefractive Keratectomy and Cross-Linking in a Cohort Having Pellucid Marginal Degeneration. Clin Ophthalmol 2024; 18:303-311. [PMID: 38317793 PMCID: PMC10840534 DOI: 10.2147/opth.s449766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 01/18/2024] [Indexed: 02/07/2024] Open
Abstract
Purpose To evaluate the efficiency, safety, and stability of a revised tissue-saving treatment protocol in a cohort having pellucid marginal degeneration (PMD). Methods A retrospective cohort study was conducted on patients with PMD and no previous treatments. A revised protocol of topo-guided photorefractive keratectomy to be followed by customized phototherapeutic keratectomy and then corneal crosslinking was evaluated by comparing the pre and postoperative outcomes regarding visual (subjective refraction) and topographic (using data from Sirius CSO topography software) outcomes. Results There were both statistically significant and clinically relevant improvements in the postoperative parameters, where each of the unaided and corrected visual acuity, spherical equivalent, refractive cylinder, K readings, topographic cylinder, inferior minus superior difference at the 2- and 4- mm diameters, coma aberration, and higher order aberrations were significantly better postoperatively (all p values were less than 0.01, except for maximum k readings where the p-value was 0.017). The safety and efficacy indices for the surgical procedure were remarkably high (1.53 ± 0.70 and 0.90 ± 0.32, respectively). Conclusion Our proposed tissue-saving protocol (which showed satisfactory results in keratoconus cases according to a previously published article by our research team) has proven its successful outcomes (both topographically and visually) in cases of PMD, which is a rare ectatic entity with guarded prognosis using the available conventional ectasia treatment modalities.
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Affiliation(s)
- Mohamed Omar Yousif
- Ophthalmology department, Faculty of Medicine, Ain Shams University, Cairo, Egypt
- Maadi Eye Subspecialty Center, Cairo, Egypt
| | - Rania Serag Elkitkat
- Ophthalmology department, Faculty of Medicine, Ain Shams University, Cairo, Egypt
- Watany Eye Hospital, Cairo, Egypt
- Watany Research and Development Center, Watany Eye Hospital, Cairo, Egypt
- Ophthalmology Department, Faculty of Medicine, MTI University, Cairo, Egypt
| | - Mohamed Nabil Hamza
- Ophthalmology department, Faculty of Medicine, Ain Shams University, Cairo, Egypt
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Fischinger I, Reifeltshammer SA, Seiler TG, Nambiar MH, Komninou MA, Büchler P, Wendelstein J, Langenbucher A, Bolz M. Analysis of Biomechanical Response After Corneal Crosslinking with Different Fluence Levels in Porcine Corneas. Curr Eye Res 2023; 48:719-723. [PMID: 37144469 DOI: 10.1080/02713683.2023.2205612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 04/14/2023] [Indexed: 05/06/2023]
Abstract
PURPOSE To evaluate corneal stiffening of porcine corneas induced by corneal crosslinking (CXL) with constant irradiance as a function of total fluence. METHODS Ninety corneas from freshly enucleated porcine eyes were divided into five groups of 18 eyes. Groups 1-4 underwent epi-off CXL using a dextran-based riboflavin solution and an irradiance of 18 mW/cm2, group 5 served as the control group. Groups 1 to 4 were treated with a total fluence of 20, 15, 10.8, and 5.4 J/cm2, respectively. Thereafter, biomechanical measurements were performed on 5 mm wide and 6 mm long strips using an uniaxial material tester. Pachymetry measurements were performed on each cornea. RESULTS At 10% strain, the stress was 76, 56, 52, and 31% higher in groups 1-4, respectively compared to the control group. The Young's modulus was 2.85 MPa for group 1, 2.53 MPa for group 2, 2.46 MPa for group 3, 2.12 MPa for group 4, and 1.62 MPa for the control group. The difference between groups 1 to 4 and the control group 5 were statistically significant (p = <0.001; p = <0.001; p = <0.001; p = 0.021). In addition, group 1 showed significantly more stiffening than group 4 (p = <0.001), no other significant differences were found. Pachymetry measurements revealed no statistically significant differences among the five groups. CONCLUSION Additional mechanical stiffening can be achieved by increasing the fluence of the CXL. There was no threshold detected up to 20 J/cm2. A higher fluence could compensate the weaker effect of accelerated or epi-on CXL procedures.
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Affiliation(s)
- Isaak Fischinger
- Augentagesklinik Spreebogen Berlin, Berlin, Germany
- Klinik für Augenheilkunde, Kepler Universitätsklinikum, Linz, Austria
- Medizinische Fakultät, Johannes Kepler Universität Linz, Linz, Austria
| | - Sophia A Reifeltshammer
- Klinik für Augenheilkunde, Kepler Universitätsklinikum, Linz, Austria
- Medizinische Fakultät, Johannes Kepler Universität Linz, Linz, Austria
| | - Theo G Seiler
- Klinik für Augenheilkunde, Universitätsklinkum Düsseldorf, Düsseldorf, Germany
- Institut für Refraktive und Ophthalmo-Chirurgie (IROC), Zurich, Switzerland
- Department of Ophthalmology, Inselspital Bern, University of Bern, Bern, Switzerland
| | - Malavika H Nambiar
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Maria A Komninou
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Philippe Büchler
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Jascha Wendelstein
- Klinik für Augenheilkunde, Kepler Universitätsklinikum, Linz, Austria
- Medizinische Fakultät, Johannes Kepler Universität Linz, Linz, Austria
| | - Achim Langenbucher
- Department of Experimental Ophthalmology, Saarland University, Homburg, Germany
| | - Matthias Bolz
- Klinik für Augenheilkunde, Kepler Universitätsklinikum, Linz, Austria
- Medizinische Fakultät, Johannes Kepler Universität Linz, Linz, Austria
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Yousif MO, Elkitkat RS, Edrees ES, Alaarag NA. Introducing a Revised Tissue Saving Protocol for Combined Topography-Guided Photorefractive Keratectomy and Cross-Linking in Keratoconic Corneas. Cornea 2023; 42:755-765. [PMID: 36728310 DOI: 10.1097/ico.0000000000003225] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Accepted: 11/26/2022] [Indexed: 02/03/2023]
Abstract
PURPOSE The aim of this study was to introduce a revised tissue-saving technique for combined topography-guided photorefractive keratectomy (PRK) and cross-linking for keratoconus (KC) treatment and to evaluate its efficacy, safety, and stability. METHODS This retrospective, noncontrolled study was performed at Maadi Eye Subspecialty Center and Eye Care Center, Cairo, Egypt. The technique was performed on virgin keratoconic corneas with 3 different morphological patterns of ectasia. It involves performing topography-guided PRK before epithelial removal, followed by customized phototherapeutic keratectomy (PTK) that is tailored to each cornea after studying the treatment profile on the laser treatment screen. The electronic medical records were explored for preoperative and postoperative data, including subjective refraction and topographic data (using Sirius topographer). RESULTS The study was conducted on 123 eyes of 93 patients with a mean age of 27.98 years ±6.06. The follow-up ranged from 6 to 36 months (mean ± SD of 16.2 months ±10.4). The results showed statistically nonsignificant differences among the 3 ectasia subgroups in treatment spherical equivalent, treatment maximum depth, thickness of removed epithelium, and thinnest residual stromal bed. There were statistically significant differences in almost all values between the preoperative and postoperative data, with significant postoperative patients' improvement ( P value <0.001). The subgroups' results were almost the same as the whole cohort's results. The safety and efficacy indices of the performed procedure showed remarkably high values (1.48 ± 0.21 and 0.87 ± 0.40, respectively). CONCLUSIONS This revised protocol for KC management maximally preserves stromal tissue with proven efficacy, safety, and stability.
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Affiliation(s)
- Mohamed Omar Yousif
- Assistant Professor of Ophthalmology, Faculty of Medicine, Ain Shams University
- Cornea and Refractive Surgery Consultant, Maadi Eye Subspecialty Center
| | - Rania Serag Elkitkat
- Assistant Professor of Ophthalmology, Faculty of Medicine, Ain Shams University
- Watany Eye Hospital
- Watany Research and Development Center
- Head of Ophthalmology Department, Faculty of Medicine, MTI University
| | - Eman Samir Edrees
- Lecturer of Ophthalmology, Faculty of Medicine, Ain Shams University; and
- Maadi Eye Subspecialty Center, Cairo, Egypt
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Malyugin BE, Belodedova A, Antonova O, Gelyastanov A, Tuuminen R, Levinger E, Achiron A, Knyazer B. Clinical comparison of manual and laser-cut corneal tunnel for intrastromal air injection in femtosecond laser-assisted deep anterior lamellar keratoplasty (DALK). Graefes Arch Clin Exp Ophthalmol 2023; 261:185-191. [PMID: 35896678 DOI: 10.1007/s00417-022-05765-9] [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: 03/15/2022] [Revised: 06/30/2022] [Accepted: 07/09/2022] [Indexed: 01/04/2023] Open
Abstract
PURPOSE The most crucial step in deep anterior lamellar keratoplasty (DALK) is to achieve a bare Descemet's membrane. We aimed to assess a new femtosecond laser software that allows for a precise intrastromal tunnel creation for big bubble (BB) air injection using a real-time microscope-integrated optical coherence tomography. MATERIALS AND METHODS A retrospective review of 61 eyes of 61 patients with keratoconus. Before introducing the new software update, DALK was performed using a partial-assisted femtosecond laser (partial-thickness circular cut followed by a lamellar cut) with manual intrastromal tunnel creation (partial FS-DALK group). After the software update, the femtosecond laser created the intrastromal tunnel (full FS-DALK group). RESULTS In the full FS-DALK group, the BB's formation was significantly higher (64.3% vs. 36.4%, p = 0.04), and surgery time was shorter (21.8 ± 5.1 vs. 25.6 ± 6.8 min, p = 0.025) than in the partial FS-DALK. Penetrating keratoplasty conversion rate (7.1% vs. 15.1%, p = 0.432) was similar between the groups. Both groups showed statistically significant improvement in uncorrected and corrected distance visual acuity, central corneal thickness, surface asymmetry, and regularity indices. Endothelial cell density loss at 12 and 18 months was lower in the full compared with the partial FS-DALK group (12 months:10.0% vs. 16; 18 months: 10.7 vs. 16.5%, p < 0.001 for both comparisons). CONCLUSIONS Creating the intrastromal guiding tunnel using FS laser for air injection resulted in a higher rate of BB formation, reduced long-term endothelial cell loss, and operating room time.
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Affiliation(s)
- Boris E Malyugin
- S. Fyodorov Eye Microsurgery Federal State Institution, Beskudnikovsky Blvd., 59a, 127486, Moscow, Russian Federation. .,A.I. Yevdokimov Moscow State University of Medicine and Dentistry, Moscow, Russian Federation. .,Department of Ophthalmology, Soroka University Medical Center and Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
| | - Alexandra Belodedova
- S. Fyodorov Eye Microsurgery Federal State Institution, Beskudnikovsky Blvd., 59a, 127486, Moscow, Russian Federation
| | - Olga Antonova
- S. Fyodorov Eye Microsurgery Federal State Institution, Beskudnikovsky Blvd., 59a, 127486, Moscow, Russian Federation
| | - Aslan Gelyastanov
- S. Fyodorov Eye Microsurgery Federal State Institution, Beskudnikovsky Blvd., 59a, 127486, Moscow, Russian Federation
| | - Raimo Tuuminen
- Helsinki Retina Research Group, University of Helsinki, Helsinki, Finland.,Department of Ophthalmology, Kymenlaakso Central Hospital, Kotka, Finland
| | - Eliya Levinger
- Tel-Aviv Sourasky Medical Center and Sackler School of Medicine, Sackler Faculty of Medicine, Tel Aviv University, Dafna St 5, Tel Aviv-Yafo, Israel
| | - Asaf Achiron
- Tel-Aviv Sourasky Medical Center and Sackler School of Medicine, Sackler Faculty of Medicine, Tel Aviv University, Dafna St 5, Tel Aviv-Yafo, Israel.
| | - Boris Knyazer
- Department of Ophthalmology, Soroka University Medical Center and Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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Muacevic A, Adler JR. A Comparison Between Cross-Linking Protocols in Patients With Progressive Keratoconus: A Review. Cureus 2022; 14:e31029. [PMID: 36475196 PMCID: PMC9718644 DOI: 10.7759/cureus.31029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/02/2022] [Indexed: 01/25/2023] Open
Abstract
Keratoconus (KC) is a noninflammatory cornea disease leading to progressive thinning, causing it to change from its normal dome shape to a cone shape. One of the novel treatments of KC is corneal collagen cross-linking (CXL). Due to its importance, many studies have been conducted to compare corneal cross-linking protocols; this review article aims to discuss corneal cross-linking and compare its different treatment options, including Dresden, accelerated, and customized protocols in patients with progressive KC and their respective long-term outcomes. A search was performed in PubMed and Google Scholar with no language, dates, or study type restriction. Most of the results showed almost no difference between protocols over traditional cross-linking. However, published data are limited, long-term outcomes of novel age groups remain unclear, and further studies are needed.
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Lenk J, Herber R, Oswald C, Spoerl E, Pillunat LE, Raiskup F. Risk Factors for Progression of Keratoconus and Failure Rate After Corneal Cross-linking. J Refract Surg 2021; 37:816-823. [PMID: 34914558 DOI: 10.3928/1081597x-20210830-01] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To assess the occurrence of risk factors for progression of keratoconus and failure rate after corneal cross-linking (CXL) in patients with progressive keratoconus. METHODS This retrospective study observed 230 eyes of 173 patients with a minimum follow-up of 36 months after CXL. A total of 185 eyes underwent CXL once (80%) (control) and 45 (20%) underwent this treatment more than once (Re-CXL-group). Subgroup analysis included standard CXL with the Dresden protocol (S-CXL group, n = 120) and accelerated CXL with a reduced radiation time of 10 minutes and a higher radiation power of 9 mW/cm2 (A-CXL group, n = 110). Risk factors of interest were age, maximum keratometry (Kmax), minimum corneal thickness (MCT), sex, and atopy (including allergic bronchial asthma, food allergy, allergic rhinitis, and neurodermatitis). RESULTS Follow-up for the control group was 76.0 ± 33.2 months. Re-CXL was performed after 46.2 ± 34.1 months overall and after 62.6 ± 41.9 months in the S-CXL subgroup and 29.2 ± 19.2 months in the A-CXL subgroup (P = .02). Kaplan-Meier analysis revealed a cumulative prediction rate of success after CXL of 92.5% (S-CXL) and 86.4% (A-CXL) after 36 months (P = .103). A high preoperative Kmax value (odds ratio = 1.056, P = .003 and odds ratio = 1.067, P = .028) in both subgroups and the presence of neurodermatitis combined with other atopic diseases in the A-CXL group (odds ratio = 11.662, P = .003) were significant risk factors for new progression of keratoconus after CXL. CONCLUSIONS Risk factors for progression of keratoconus after CXL are both high preoperative Kmax values and the presence of neurodermatitis combined with other atopic diseases. Patients with severe atopy should receive the S-CXL procedure. [J Refract Surg. 2021;37(12):816-823.].
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Nicula CA, Rednik AM, Nicula AP, Bulboaca AE, Nicula D, Horvath KU. Comparative Results Between "Epi-Off" Accelerated and "Epi-Off" Standard Corneal Collagen Crosslinking-UVA in Progressive Keratoconus - 7 Years of Follow-Up. Ther Clin Risk Manag 2021; 17:975-988. [PMID: 34522101 PMCID: PMC8434931 DOI: 10.2147/tcrm.s321410] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 08/14/2021] [Indexed: 11/23/2022] Open
Abstract
Purpose The purpose of the present study was to assess the long-term efficiency and safety of the “epi-off” accelerated CXL (9 mW/cm2 for 10 minutes) in comparison to the standard “epi-off” CXL (3 mW/cm2 for 30 minutes) in terms of topographical and keratometric parameters, refractive data and visual outcomes at 7 years of follow-up, in progressive keratoconus. Material and Method A retrospective and comparative study was performed. A total of 183 eyes from 183 patients with documented progressive keratoconus were included in the study. The patients were divided in two groups: 93 eyes from 93 patients underwent “epi-off” standard cross-linking technique (3 mW/cm2 for 30 minutes) (S-CXL group) and 90 eyes from 90 patients underwent accelerated “epi-off” corneal CXL technique (9 mW/cm2 for 10 minutes) (A-CXL group). Results Improvements in uncorrected distance visual acuity (UDVA) were statistically significant compared to baseline values in both groups at each time-point visit (p=0.0421 at 1 year, p=0.0411 at 7 years for A-CXL and p=0.0375 at 1 year, p=0.0389 at 7 years for S-CXL). At 7 years there was a statistically significant increase in CDVA (p=0.039 in the A-CXL group and p=0.0343 in the S-CXL group at 7 years). Statistically significant reduction was noticed in Ksteep (p=0.0411 in A-CXL group and p=0.0224 in S-CXL group), Kflat (p=0.0198 in A-CXL group and p=0.008 in S-CXL group), K mean (p=0.0106 in A-CXL group and p=0.0193 in S-CXL group) and Kmax (p=0.0413 in A-CXL group and p=0.054 in S-CXL group) at 7 years, compared to baseline values, in both groups, but without any statistically difference between the two procedures, at all time-point visits (p>0.05). Conclusion The long-term outcomes of “epi-off” accelerated corneal collagen crosslinking-UVA (9 mW/cm2 for 10 minutes) are similar to standard “epi-off” corneal collagen crosslinking procedure in the treatment of progressive keratoconus.
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Affiliation(s)
- Cristina Ariadna Nicula
- Department of Ophthalmology, Medicine and Pharmacy University "Iuliu Hațieganu", Cluj-Napoca, Romania.,Oculens Clinic, Cluj-Napoca, Romania
| | - Anca Maria Rednik
- Eye County Hospital, Department of Ophthalmology, Cluj-Napoca, Romania
| | | | - Adriana Elena Bulboaca
- Department of Pathophysiology, Medicine and Pharmacy University "Iuliu Hațieganu", Cluj Napoca, Romania
| | | | - Karin Ursula Horvath
- Department of Ophthalmology, Medicine and Pharmacy Science and Technology University "George Emil Palade", Târgu Mureș, Romania
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Safety and Efficacy of Corneal Minimized-Volume Ablation With Accelerated Cross-Linking in Improving Visual Function for Keratoconus. Cornea 2021; 39:1485-1492. [PMID: 32826646 DOI: 10.1097/ico.0000000000002462] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
PURPOSE To evaluate the safety and efficacy of corneal minimized-volume ablation with accelerated cross-linking in improving visual function in keratoconus eyes. METHODS Through a pilot study, 25 eyes of 25 consecutive patients with keratoconus grade I-III were recruited that underwent corneal transepithelial photorefractive keratectomy with "minimized volume" ablation profile and accelerated corneal cross-linking in the same session. Corrected and uncorrected distance visual acuities, manifest refraction, corneal curvature and higher-order aberrations, endothelial cells, and the ocular modulation transfer function were assessed preoperatively and postoperatively, with a minimum follow-up of 6 months. A P value < 0.05 was the threshold of statistical significance. RESULTS At 8.2 ± 3.6 months postoperatively, the mean corrected and uncorrected distance visual acuities (LogMAR) were 0.07 ± 0.15 and 0.45 ± 0.39, significantly improving from the baseline of 0.24 ± 0.24 (P8m-before = 0.005) and 1.12 ± 0.33 (P8m-before < 0.001), respectively. Spherical equivalent was -2.80 ± 2.72 diopters (D), significantly decreasing from the baseline of -6.61 ± 3.06 D (P8m-before < 0.001), whereas the attempted corrected spherical equivalent was-2.30 ± 1.22 D. Meanwhile, a significant reduction was found in higher-order aberration, along with the postoperative improvement in ocular modulation transfer function. Corneal surface morphological parameters were found with significant decreases postoperatively (index of surface variance: P8m-before = 0.003; index of vertical asymmetry: P8m-before = 0.005; keratoconus index: P8m-before = 0.004; center keratoconus index: P8m-before = 0.003; and index of height decentration: P8m-before < 0.001). Nevertheless, no significant change was found in posterior corneal curvature or endothelial cell density between pre- and post-operative periods. CONCLUSIONS Corneal minimized-volume ablation with accelerated cross-linking was an effective and safe option for correction of mild refractive error, leading to significant improvement of visual function in patients with keratoconus.
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Zhang Y, Chen Y. Topography-guided corneal surface laser ablation combined with simultaneous accelerated corneal collagen cross-linking for treatment of keratoconus. BMC Ophthalmol 2021; 21:286. [PMID: 34301233 PMCID: PMC8305492 DOI: 10.1186/s12886-021-02042-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Accepted: 07/09/2021] [Indexed: 12/20/2022] Open
Abstract
Background to study the outcomes of topography-guided customized excimer laser subepithelial ablation combined with accelerated CXL for progressive keratoconus. Methods Thirty-one eyes of 30 patients with progressive keratoconus were included in this prospective study. Topography-guided excimer laser ablation without refractive correction was performed. Simultaneous accelerated collagen cross-linking with ultraviolet light of 30 mW/cm2 for 4 min was followed. Uncorrected distance visual acuity (UCVA), manifest refraction, corrected distance visual acuity (CDVA), tomograghy were examined at postoperative 1, 6, and 12 months. Results UDVA improved slightly after surgery (P > 0.05). BSCDVA improved significantly from 0.32 ± 0.20 logMAR to 0.15 ± 0.14 logMAR at postoperative 12 months (P < 0.05). During 12-month follow-ups, there were no significant differences in manifest refraction and corneal keratometry except for maximal keratometry value of the anterior surface (Kapex), which decreased significantly from 57.23 ± 5.09D to 53.13 ± 4.47D (P < 0.05). Even though the thinnest corneal thickness decreased from 465 ± 24 μm to 414 ± 35 μm (P < 0.05), curvature asymmetry index front (SIf), keratoconus vertex front (KVf) and Baiocchi Calossi Versaci index front (BCVf) decreased significantly till postoperative 12 months (P < 0.05). Corneal higher-order aberrations and coma also decreased significantly till 12 months after surgery (P < 0.05). Conclusions Topography-guided surface ablation without refractive correction combined with simultaneous accelerated collagen cross-linking provided good stability in refraction and corneal curvature, and also showed significant improvement in BSCDVA, corneal regularity and corneal optical quality.
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Affiliation(s)
- Yu Zhang
- Department of Ophthalmology, Beijing key laboratory of restoration of damaged ocular nerve, Peking University Third Hospital, 49 North Huayuan Road, Haidian District, 100191, Beijing, China
| | - Yueguo Chen
- Department of Ophthalmology, Beijing key laboratory of restoration of damaged ocular nerve, Peking University Third Hospital, 49 North Huayuan Road, Haidian District, 100191, Beijing, China.
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Han D, He MN, Zhu Y, Zhang Y, Wei RH. Protective effects of riboflavin-UVA-mediated posterior sclera collagen cross-linking in a guinea pig model of form-deprived myopia. Int J Ophthalmol 2021; 14:333-340. [PMID: 33747806 DOI: 10.18240/ijo.2021.03.01] [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: 03/10/2020] [Accepted: 12/21/2020] [Indexed: 01/17/2023] Open
Abstract
AIM To evaluate the effect of posterior sclera collagen cross-linking induced by riboflavin-ultraviolet A (UVA) on form-deprived myopia in guinea pigs. METHODES Twenty-five pigmented guinea pigs of 3-week-old were randomly assigned into 4 groups that included normal control (NOR, n=7), form-deprived (FDM, n=7), normal with riboflavin-UVA cross-linking (NOR+CL, n=5) and form-deprived with cross-linking (FDM+CL, n=6). The NOR+CL group and the FDM+CL group received the riboflavin-UVA induced cross-linking at day 0. FDM was induced by monocularly deprived with facemask in the right eyes. The refraction, axial length and corneal curvature were measured by retinoscopy, A-scan and keratometer respectively in scheduled time points (day 0 and 1, 2, 3, 4wk after form-deprivation). At the end of 4 weeks' experiment, stress-strain tests of sclera were measured and morphological changes of sclera and retina were examined. RESULTS After 4wk, the interocular difference of refractive error were -0.11±0.67, -2.93±0.56, 1.10±0.58, and -1.63±0.41 D in the NOR, FDM, NOR+CL, and FDM+CL groups respectively. Mixed-effect linear model revealed significant effect of FDM (P<0.01) and CL (P<0.001). Also, after 4wk, the interocular difference of axial length were 0.01±0.04, 0.29±0.07, -0.13±0.06, and 0.11±0.05 mm in the NOR, FDM, NOR+CL, and FDM+CL group. Mixed-effect linear model revealed significant effect of FDM (P<0.001) and CL (P<0.01). As for corneal curvature, significant interocular difference have not found between any of the two groups. At the end of this experiment, the ultimate stress and elastic modulus were found significantly increased in both CL groups. But no difference was found in the groups without cross-linked. There was no abnormality observed in the retina and RPE cells of the treated eyes. CONCLUSION The posterior sclera collagen cross-linking induced by riboflavin-UVA can slow down the progress of myopia and increase the sclera biomechanical strength in the guinea pig model of form-deprived myopia.
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Affiliation(s)
- Ding Han
- Tianjin Key Laboratory of Retinal Functions and Diseases, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin 300384, China
| | - Mei-Nan He
- Tianjin Key Laboratory of Retinal Functions and Diseases, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin 300384, China
| | - Ying Zhu
- Tianjin Key Laboratory of Retinal Functions and Diseases, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin 300384, China
| | - Yan Zhang
- Tianjin Key Laboratory of Retinal Functions and Diseases, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin 300384, China
| | - Rui-Hua Wei
- Tianjin Key Laboratory of Retinal Functions and Diseases, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin 300384, China
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Cunha AM, Sardinha T, Torrão L, Moreira R, Falcão-Reis F, Pinheiro-Costa J. Transepithelial Accelerated Corneal Collagen Cross-Linking: Two-Year Results. Clin Ophthalmol 2020; 14:2329-2337. [PMID: 32884233 PMCID: PMC7434572 DOI: 10.2147/opth.s252940] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Accepted: 06/30/2020] [Indexed: 11/23/2022] Open
Abstract
PURPOSE To report 2-year outcomes of trans-epithelial accelerated corneal collagen crosslinking (TE-ACXL) procedure in the treatment of progressive keratoconus patients. PATIENTS AND METHODS Twenty-four eyes from 24 patients who underwent TE-ACXL (6mW/cm2 for 15 minutes) were included in this retrospective interventional study. Best-corrected visual acuity (BCVA), keratometry values, thinnest corneal thickness (PachyMin) and topometric indexes were analysed preoperatively and at 6-month, 12-month, 18-month and 24-month postoperative. Progression was assessed by increase ≥1.00D in maximum keratometry (Kmax); increase ≥1.00D in corneal astigmatism; decrease ≥2% in PachyMin; increase ≥0.42 in D-index. RESULTS There were no complications during or after TE-ACXL. No significant differences (Δ) were observed between baseline and 12-month or 24-month postoperative: ∆BCVA (-0.08 ± 0.25, p=0.190; -0.04 ± 0.17, p=0.588), ∆Kmax (-0.08 ± 1.32, p=0.792; -1.04 ± 1.89, p=0.135), ∆Astigmatism (-0.15 ± 0.89, p=0.485; -0.24 ± 1.38, p=0.609), ∆PachyMin (-0.56 ± 15.70, p=0.882; 0.56 ± 18.74, p=0.931), ∆Index Surface Variation (∆ISV) (-2.11 ± 10.27, p=0.395; -4.67 ± 17.32, p=0.442), ∆Index Vertical Asymmetry (∆IVA) (-0.05 ± 0.17, p=0.208; -0.08 ± 0.26, p=0.397), ∆Index Height Decentration (∆IHD) (0.00 ± 0.02, p=0.368; -0.01 ± 0.04, p=0.484), ∆KI (0.00 ± 0.05, p=0.851; 0.01 ± 0.06, p=0.877) and ∆D-index (0.15 ± 1.14, p=0.572; 0.06 ± 1.36, p=0.892). Eleven to 33% of patients had disease progression at 24-month postoperative according to the parameters used to determine progression. CONCLUSION Although some patients maintain disease progression, TE-ACXL seems to be a safe and effective treatment for keratoconus over the 2-year follow-up period. Studies with longer follow-up periods and larger patient cohorts are recommended.
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Affiliation(s)
- Ana Maria Cunha
- Department of Ophthalmology, Centro Hospitalar De São João, Porto, Portugal
| | - Tiago Sardinha
- Faculty of Medicine, University of Porto, Porto, Portugal
| | - Luís Torrão
- Department of Ophthalmology, Centro Hospitalar De São João, Porto, Portugal
| | - Raúl Moreira
- Department of Ophthalmology, Centro Hospitalar De São João, Porto, Portugal
| | - Fernando Falcão-Reis
- Department of Ophthalmology, Centro Hospitalar De São João, Porto, Portugal
- Department of Surgery and Physiology, Faculty of Medicine, University of Porto, Porto, Portugal
| | - João Pinheiro-Costa
- Department of Ophthalmology, Centro Hospitalar De São João, Porto, Portugal
- Department of Biomedicine, Faculty of Medicine, University of Porto, Porto, Portugal
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Hatch W, El-Defrawy S, Ong Tone S, Stein R, Slomovic AR, Rootman DS, Rabinovitch T, Kranemann C, Chew HF, Chan CC, Bujak MC, Cohen A, Lebovic G, Jin Y, Singal N. Accelerated Corneal Cross-Linking: Efficacy, Risk of Progression, and Characteristics Affecting Outcomes. A Large, Single-Center Prospective Study. Am J Ophthalmol 2020; 213:76-87. [PMID: 31945333 DOI: 10.1016/j.ajo.2020.01.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 01/02/2020] [Accepted: 01/03/2020] [Indexed: 10/25/2022]
Abstract
PURPOSE We examined the efficacy and preoperative characteristics that affect outcomes of accelerated (9 mW/cm2 for 10 minutes) corneal cross-linking (CXL). DESIGN Prospective single-center observational cohort study. METHODS We enrolled 612 eyes of 391 subjects with progressive keratoconus (n = 589), pellucid marginal degeneration (n = 11), and laser in situ keratomileusis-induced ectasia (n = 12). We evaluated best spectacle-corrected visual acuity (BSCVA), topography, refraction, endothelial cell density, corneal thickness, haze, intraocular pressure, and visual function before and 12 months after the CXL procedure. We tabulated the proportion of those with progression of maximum keratometry (Kmax). We included participant's race, age, sex, and the presence of preoperative apical scarring and environmental allergies in a multivariable linear regression model to determine the effect of these characteristics on outcomes. RESULTS At 1 year there was no significant change in mean Kmax (n = 569). Progression of Kmax was higher in subgroups with a baseline Kmax >58 diopters (n = 191) and those 14-18 years of age (n = 53). Preoperative BSCVA, Kmax, refraction, corneal cylinder, coma, central corneal thickness, and vision function were statistically and clinically significant predictors of outcomes (P < .001). Preoperative apical scarring led to worsening haze (P = .0001), more astigmatism (P = .002), more central corneal thinning (P = .002), and was protective to the endothelium (P = .008). Race, age, and sex affected some outcomes. CONCLUSION Mean Kmax was stable at 1 year after accelerated CXL. Younger patients and those with a higher preoperative Kmax need to be monitored closely for progression. Preoperative BSCVA, topography, refraction, CCT, and apical scarring were significant predictors of outcomes.
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Kasai K, Kato N, Den S, Konomi K, Shinzawa M, Shimazaki J. A prospective, randomized clinical study comparing accelerated corneal collagen crosslinking with 5% NaCl hypertonic saline for bullous keratopathy in Asian eyes. Medicine (Baltimore) 2019; 98:e18256. [PMID: 31860972 PMCID: PMC6940161 DOI: 10.1097/md.0000000000018256] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND We compared the clinical outcomes of accelerated corneal collagen crosslinking (CXL) and 5% NaCl hypertonic saline (HS) for the treatment of symptomatic bullous keratopathy (BK). METHODS A randomized controlled trial was held at Department of Ophthalmology, Tokyo Dental College Ichikawa General Hospital, Chiba, Japan. Twenty-three eyes of 23 consecutive patients with symptomatic BK were enrolled. The etiology of BK included pseudophakic BK, previous keratoplasty, previous endotheliitis, previous glaucoma surgery, trauma, herpes infection, as well as unknown causes. Eleven eyes received epi-off accelerated CXL (with epithelial abrasion and 18 mW/cm ultraviolet A irradiation for 5 minutes) and 12 eyes received HS instillation. In addition to the usual ophthalmic examination, the best-corrected visual acuity (BCVA) and central corneal thickness (CCT) were determined. The CCT was measured using anterior segment optical coherence tomography before and up to 6 months after treatments. Subjective symptoms of pain, blurred vision, photophobia, and irritation were also recorded. RESULTS The follow-up was completed for all patients in the CXL group. However, 6 patients in the HS group requested CXL treatments after 3 months. The BCVA was not significantly changed during the study periods in both groups. The CCT was significantly thinner in the CXL group compared to the HS group at 1 and 6 months (P = .015 and 0.144, respectively). Among the subjective symptoms recorded, irritation was significantly lower in the CXL group at 1 month (P = .013). CONCLUSIONS Accelerated CXL may produce transient improvement in pain and corneal edema in patients with BK.
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Affiliation(s)
- Kozue Kasai
- Departments of Ophthalmology, Jikei University School of Medicine, Tokyo,
- Departments of Ophthalmology, Tokyo Dental College Ichikawa General Hospital, Chiba, Japan
| | - Naoko Kato
- Departments of Ophthalmology, Tokyo Dental College Ichikawa General Hospital, Chiba, Japan
| | - Seika Den
- Departments of Ophthalmology, Jikei University School of Medicine, Tokyo,
- Departments of Ophthalmology, Tokyo Dental College Ichikawa General Hospital, Chiba, Japan
| | - Kenji Konomi
- Departments of Ophthalmology, Tokyo Dental College Ichikawa General Hospital, Chiba, Japan
| | - Megumi Shinzawa
- Departments of Ophthalmology, Tokyo Dental College Ichikawa General Hospital, Chiba, Japan
| | - Jun Shimazaki
- Departments of Ophthalmology, Tokyo Dental College Ichikawa General Hospital, Chiba, Japan
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Whether Keratectasia Area Shown in Corneal Topography Is Appropriate for Evaluating the Effect of Corneal Cross-Linking for Keratoconus: A 12-Month Follow-Up Study. BIOMED RESEARCH INTERNATIONAL 2019; 2019:1762537. [PMID: 31073520 PMCID: PMC6470445 DOI: 10.1155/2019/1762537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 02/03/2019] [Accepted: 03/20/2019] [Indexed: 11/24/2022]
Abstract
Purpose To analyze the keratectasia area (KEA) shown in corneal topography before and after corneal cross-linking (CXL) in patients with progressive keratoconus (KC) and figure out whether KEA is appropriate for evaluating the effect of CXL. Methods A retrospective analysis was conducted in 34 eyes from 24 progressive KC patients who have underwent CXL from 2015 to 2017. Area with K-value more than 47D shown in the corneal topography was marked and identified as KEA. Keratometry (K1, K2, and Kmax), KEA, thinnest corneal thickness (TCT), and endothelial cell density (ECD) were evaluated preoperatively or at months 3, 6, and 12 postoperatively. The changes of KEA before and after operation were evaluated. The relation of KEA and other parameters, including Kmax and TCT, was analyzed. Results Linear regression model revealed the KEA, Kmax, K1, and K2 decreased after CXL in model y = 0.9622 -0.02408 x (P<0.05), y = 0.9982 -0.003469 x(P<0.05), y = 0.9977 + -0.001347 x(P<0.05), y = 0.9992 + -0.001779 x(P<0.05) (y represents KEA, Kmax, K1, or K2; x represents time (month)). The KEA is significantly decreased in early stage (before month 3) (P<0.05); however, the Kmax, K1, and K2 have no significant decrease in early stage (P= 0.09, 0.19, 0.32). Conclusions The KEA is more sensitive than K-value in describing the morphological changes of cornea after CXL, especially in early stage after treatment.
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Comparative Functional Outcomes After Corneal Crosslinking Using Standard, Accelerated, and Accelerated With Higher Total Fluence Protocols. Cornea 2019; 38:433-441. [PMID: 30681515 DOI: 10.1097/ico.0000000000001878] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE To compare the relative 12-month corneal crosslinking (CXL) functional outcomes using standard protocol and accelerated protocols in patients with progressive keratoconus. METHODS CXL was performed using 3 epithelium-off protocols: standard [3 mW/cm for 30 minutes, 5.4 J/cm (S3/30-CXL)], accelerated with equivalent total irradiance [9 mW/cm for 10 minutes, 5.4 J/cm (A9/10-CXL)], and accelerated with increased total irradiance [30 mW/cm for 4 minutes, 7.2 J/cm (A30/4-CXL)]. Efficacy measurements were evaluated 12 months after treatment with Scheimpflug imaging (Pentacam HR) and included change in maximum keratometry (K Max), corrected distance visual acuity (CDVA), other keratometric variables, pachymetry, keratoconus indices, astigmatism, asphericity, manifest refraction, and higher order aberrations. RESULTS Ninety-three eyes (67 patients) were evaluated: 35 eyes (26 patients) with S3/30-CXL, 29 eyes (19 patients) with A9/10-CXL, and 29 eyes (22 patients) with A30/4-CXL. Mean [INCREMENT]K Max was -1.53 ± 2.1 diopter (D) for S3/30-CXL, -0.71 ± 1.3 D for A9/10-CXL, and -0.70 ± 2.3 D for A30/4-CXL (P = 0.37). Mean [INCREMENT]CDVA(logMAR) was -0.18 ± 0.2 for S3/30-CXL, -0.13 ± 0.2 for A9/10-CXL, and -0.18 ± 0.2 for A30/4-CXL (P = 0.79). [INCREMENT]K Mean (r = -0.29 to -0.46), anterior asphericity (r = -0.34 to -0.40), and central keratoconus index (r = -0.18 to -0.38) best correlated with [INCREMENT]CDVA. S3/30-CXL had greater changes in index of surface variance, index of vertical asymmetry, keratoconus index, and regularization index compared to A9/10-CXL and A30/4-CXL. There were no other differences between protocols. CONCLUSIONS All 3 protocols showed improvements in K Max, CDVA, and other variables, with similar functional outcomes for each despite greater change in keratoconus indices after S3/30-CXL. Correlations between change in measured variables and CDVA were poor overall; however, K Mean, central keratoconus index, and anterior asphericity were better correlated with CDVA than K Max.
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Kim CY, Kim MK. Effect of the retention ring-assisted continuous application of riboflavin in pulsed-light accelerated corneal collagen cross-linking on the progression of keratoconus. BMC Ophthalmol 2019; 19:72. [PMID: 30866862 PMCID: PMC6417158 DOI: 10.1186/s12886-019-1085-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 03/06/2019] [Indexed: 01/10/2023] Open
Abstract
Background To investigate the efficacy and safety of the retention ring-assisted continuous application of 0.1% riboflavin in pulsed-light accelerated corneal collagen cross-linking on the progression of keratoconus. Methods The medical records of 20 eyes of 18 patients with progressive keratoconus who received collagen cross-linking at Seoul National University Hospital were retrospectively reviewed. Isotonic 0.1% riboflavin was continuously applied for 10 min using an 8.0-mm retention ring before the irradiation and accelerated cross-linking was applied with 30-mW pulsed-ultraviolet light at a wavelength 365 nm for eight minutes (1 s on/1 s off; 30 mW/cm2, cumulative dose of 7 .2J/cm2) without further intermittent application of riboflavin. Visual acuity, refractive error, topographic index, corneal thickness, and endothelial cell density were evaluated before the operation and at 1, 3, 6, and 12 months. Results The best corrected visual acuity in logMAR improved from preoperative 0.43 to 0.17 in 12 months (p = 0.050). Maximum keratometry decreased from 51.8 D to 50.4 D at 6 months (p = 0.015) and 50.1 D at 12 months (p = 0.0003). Astigmatism decreased from preoperative 5.5 D to 4.1 D at 12 months (p < 0.0001). Thinnest corneal thickness decreased at three and 6 months but recovered in 12 months (p > 0.05). Endothelial cell density decreased at postoperative 1 month (p = 0.02) but gradually recovered in 12 months (p > 0.05). Conclusions Retention ring-assisted continuous application of riboflavin for 10 minutes in pulsed-light accelerated cross-linking is a comparably safe and effective treatment for halting the progression of keratoconus in 12 months when compared to outcomes of the standard Dresden protocol shown in previous reports. Electronic supplementary material The online version of this article (10.1186/s12886-019-1085-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Chung Young Kim
- Department of Ophthalmology, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul, 110-744, South Korea
| | - Mee Kum Kim
- Department of Ophthalmology, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul, 110-744, South Korea. .,Laboratory of Ocular Regenerative Medicine and Immunology, Biomedical Research Institute, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul, 110-744, South Korea.
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Randomized Study of Collagen Cross-Linking With Conventional Versus Accelerated UVA Irradiation Using Riboflavin With Hydroxypropyl Methylcellulose: Two-Year Results. Cornea 2019; 38:203-209. [PMID: 30365412 DOI: 10.1097/ico.0000000000001791] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To compare the clinical outcome 2 years after corneal collagen cross-linking (CXL) with conventional and accelerated ultraviolet A (UVA) irradiation using riboflavin with hydroxypropyl methylcellulose. METHODS Prospective randomized controlled study. Forty patients with keratoconus (40 eyes) were randomized to either CXL using conventional 3 mW/cm UVA irradiation for 30 minutes (CXL30 group) or accelerated 9 mW/cm UVA irradiation for 10 minutes (CXL10 group). In both groups, a solution of 0.1% riboflavin with 1.1% hydroxypropyl methylcellulose (methylcellulose-riboflavin) was used. Uncorrected distance visual acuity, corrected distance visual acuity (CDVA), and Scheimpflug tomography were performed at baseline and after 24 months. RESULTS Both groups had statistically significant improvement in CDVA and maximum keratometric reading compared with baseline; however, with no statistically significant difference in the change between the 2 groups. No significant changes in flattest, steepest and mean keratometry (K1, K2 and K mean) were found in either of the groups. There were no statistically significant changes in ECD in either group after 2 years or in the difference in the change between the 2 groups. A literature review showed comparative clinical outcome after accelerated CXL compared with conventional CXL; however, in several studies, there was a tendency for less pronounced corneal flattening after accelerated CXL. CONCLUSIONS Improvement in visual acuity and maximum keratometric reading 2 years after CXL was found after both conventional and accelerated UVA irradiation using methylcellulose-riboflavin. This suggests that when using riboflavin with methylcellulose, the less time-consuming accelerated protocol is a valuable and effective option in CXL treatment.
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Effectiveness and safety of accelerated (9 mW/cm 2) corneal collagen cross-linking for progressive keratoconus: a 24-month follow-up. Eye (Lond) 2019; 33:812-818. [PMID: 30610230 DOI: 10.1038/s41433-018-0323-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Revised: 11/21/2018] [Accepted: 12/07/2018] [Indexed: 11/09/2022] Open
Abstract
OBJECTIVES To examine the effectiveness and safety of accelerated corneal collagen cross-linking (CXL) for keratoconus over a 24-month period and to explore potential prognostic factors for post-treatment visual outcome and progression. METHODS A retrospective, non-comparative, interventional case series. All patients who underwent accelerated epithelium-off CXL, using 9 mW/cm2 ultraviolet-A irradiation for 10 min, for progressive keratoconus in Sunderland Eye Infirmary, UK, between May 2014 and July 2016 were included. All patients completed 24 months' post-CXL follow-up. Significant post-CXL progression of keratoconus was defined as >1 D increase in Kmax from preoperative to 24-month visit. RESULTS Fifty-two eyes of 48 patients were included. At 24-month post-CXL, there was a significant improvement in corrected-distance visual acuity (CDVA; -0.05 LogMAR; p = 0.026), Kmax (-1.68 D; p < 0.001), K1 (-0.64 D; p = 0.002) and Kmean (-0.50 D; p = 0.009). The proportion of eyes with CDVA ≥ 0.3 LogMAR significantly improved from 43 (82.7%) eyes preoperatively to 50 (96.2%) eyes at 24 months (p = 0.026). Corneal haze (12, 23.1%) was the only postoperative complication and no adverse event was noted. Final CDVA was associated with lower CDVA (p = 0.002) and greater Kmax (p = 0.018) at baseline. Post-CXL progression of keratoconus was associated with greater preoperative Kmax (p = 0.12) and Kmean (p = 0.11), though statistical significances were not achieved. CONCLUSIONS Accelerated CXL (9 mW/cm2) serves as an effective and safe treatment for halting the progression of keratoconus and stabilising the vision over a 24-month period. Our observation suggests that accelerated CXL might be more effective in stabilising keratoconus of milder severity; however further larger studies are required to elucidate this finding.
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Gu L, Shan T, Ma YX, Tay FR, Niu L. Novel Biomedical Applications of Crosslinked Collagen. Trends Biotechnol 2018; 37:464-491. [PMID: 30447877 DOI: 10.1016/j.tibtech.2018.10.007] [Citation(s) in RCA: 148] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2018] [Revised: 10/19/2018] [Accepted: 10/19/2018] [Indexed: 02/08/2023]
Abstract
Collagen is one of the most useful biopolymers because of its low immunogenicity and biocompatibility. The biomedical potential of natural collagen is limited by its poor mechanical strength, thermal stability, and enzyme resistance, but exogenous chemical, physical, or biological crosslinks have been used to modify the molecular structure of collagen to minimize degradation and enhance mechanical stability. Although crosslinked collagen-based materials have been widely used in biomedicine, there is no standard crosslinking protocol that can achieve a perfect balance between stability and functional remodeling of collagen. Understanding the role of crosslinking agents in the modification of collagen performance and their potential biomedical applications are crucial for developing novel collagen-based biopolymers for therapeutic gain.
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Affiliation(s)
- Lisha Gu
- Department of Operative Dentistry and Endodontics, Guanghua School of Stomatology and Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, PR China
| | - Tiantian Shan
- Department of Operative Dentistry and Endodontics, Guanghua School of Stomatology and Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, PR China
| | - Yu-Xuan Ma
- State Key Laboratory of Military Stomatology, National Clinical Research Center for Oral Diseases and Shaanxi Key Laboratory of Stomatology, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi'an, Shaanxi, PR China
| | - Franklin R Tay
- State Key Laboratory of Military Stomatology, National Clinical Research Center for Oral Diseases and Shaanxi Key Laboratory of Stomatology, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi'an, Shaanxi, PR China; The Dental College of Georgia, Augusta University, Augusta, GA, USA.
| | - Lina Niu
- State Key Laboratory of Military Stomatology, National Clinical Research Center for Oral Diseases and Shaanxi Key Laboratory of Stomatology, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi'an, Shaanxi, PR China; The Dental College of Georgia, Augusta University, Augusta, GA, USA.
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Correlation of Demarcation Line Depth With Medium-Term Efficacy of Different Corneal Collagen Cross-Linking Protocols in Keratoconus. Cornea 2018; 37:1511-1516. [PMID: 30157054 DOI: 10.1097/ico.0000000000001733] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To compare demarcation line depth (DD) and topographic changes among different corneal collagen cross-linking (CXL) protocols and to evaluate the relation of DD with medium-term efficacy of CXL in halting progression of keratoconus. METHODS The study included 124 patients (mean age 19 ± 4.8 years) with progressive keratoconus who underwent conventional (3 mW/cm/30 min), accelerated (18 mW/cm/5 min), or transepithelial (TE) CXL (3 mW/cm/30 min) and followed up for at least 2 years. Baseline and final corneal topographic parameters and DD determined with anterior segment optical coherence tomography 1 month after CXL were compared among the protocols and the correlation between DD and topographic changes at the end of 24 months was analyzed. P < 0.05 was considered as statistically significant. RESULTS Mean DD was significantly higher in the conventional and accelerated groups (335.19 ± 71.13 μm and 304.97 ± 94.45 μm, respectively) compared with the TE group (239.92 ± 71.37 μm) (P < 0.001). After conventional and TE CXL, keratometric parameters improved remarkably, whereas accelerated CXL only lowered K1 and Kmax (P < 0.05). No correlation was found between DD and topographic changes (P > 0.05). Progression was detected in 3 eyes in the conventional group (4.1%), 3 in the accelerated group (7.7%), and none in the TE group. The use of either riboflavin D or M made no differences in terms of DD and topographic parameters (P > 0.05). CONCLUSIONS In conventional and accelerated protocols, corneal stromal demarcation line is deeper compared with TE CXL; however, the DD has no correlation with topographic changes, which means that DD is not a direct measure for the efficacy of CXL.
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Böhm M, Shajari M, Remy M, Kohnen T. Corneal densitometry after accelerated corneal collagen cross-linking in progressive keratoconus. Int Ophthalmol 2018; 39:765-775. [PMID: 29582259 DOI: 10.1007/s10792-018-0876-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 02/21/2018] [Indexed: 11/25/2022]
Abstract
PURPOSE To analyze changes in corneal densitometry 3 months after accelerated corneal collagen cross-linking (CXL) measured with Scheimpflug tomography. METHODS In this study we reviewed charts and anterior segment data of patients who had undergone accelerated pulsed epithelium-off CXL (30 mW/cm2 for 4 min, 8 min total radiation time) for treatment of progressive keratoconus in the Department of Ophthalmology, Goethe University, Frankfurt, Germany. Visual, topographic, pachymetric and densitometric data were extracted before surgery and at the 3-month follow-up. Corneal densitometry measurements from different corneal layers and zones obtained using Scheimpflug tomography (Pentacam HR, Oculus). RESULTS The study investigated 12 eyes of 12 patients. The anterior (120 μm) stromal layer within the 0.0 to 2.0 mm and 2.0 to 6.0 mm concentric zones showed a significant elevation of mean densitometry 3 months post-surgery (P = 0.045; P = 0.015) compared to baseline. A mean stromal demarcation line was apparent at a depth of 203.00 μm ± 13.53 (SD). After accelerated CXL, no change in mean corrected distance visual acuity (LogMAR) was observed but a thinning of the cornea measured by a significant reduction in central pachymetry (μm). CONCLUSION Accelerated CXL results in an increase in corneal densitometry, particularly in the anterior stromal layer within the two central concentric zones (0.0 to 2.0 mm and 2.0 to 6.0 mm) of the cornea at 3 months postoperatively. The changes in corneal densitometry of the anterior stromal layer did not correlate with postoperative visual acuity or central pachymetry.
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Affiliation(s)
- Myriam Böhm
- Department of Ophthalmology, Goethe University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany
| | - Mehdi Shajari
- Department of Ophthalmology, Goethe University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany
| | - Matthias Remy
- Department of Ophthalmology, Goethe University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany
| | - Thomas Kohnen
- Department of Ophthalmology, Goethe University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.
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