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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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Feld S, Flockerzi E, Daas L, Xanthopoulou K, Sideroudi H, Langenbucher A, Seitz B. [Corneal biomechanics before and after cross-linking in patients with keratoconus]. DIE OPHTHALMOLOGIE 2023; 120:940-946. [PMID: 37043004 DOI: 10.1007/s00347-023-01839-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 02/10/2023] [Accepted: 03/01/2023] [Indexed: 04/13/2023]
Abstract
OBJECTIVE The aim of this study was to analyze the effect of corneal cross-linking (CXL) on corneal biomechanics and visual acuity. PATIENTS AND METHODS The examination results before and after CXL in 56 eyes of 56 patients between 2017 and 2021 were evaluated retrospectively. The last preoperative examination was compared to the postoperative follow-up values after 6 and 12 months. The main outcome measures included various biomechanical parameters from the Corvis ST (CST), Pentacam and the visual acuity (logMAR, "logarithm of the Minimal Angle of Resolution"). For longitudinal evaluation, a general linear model for repeated measurements was used. A p-value of less than 0.05 was considered to show a statistically significant result. Bonferroni correction was applied for multiple comparisons. RESULTS The maximum corneal refractive power Kmax decreased slightly without statistical significance from 57.1 ± 6.1 diopters (dpt) to 56.6 ± 6.3 dpt after 6 months (p = 0.076) and 56.8 ± 6.6 dpt after 12 months (p = 0.443). The Pentacam parameter Belin/Ambrósio Enhanced Ectasia Total Deviation Display (BAD D) showed a statistically significant increase from the preoperative value of 8.4 ± 3.7 to the postoperative value of 9.1 ± 3.6 after 6 months (p < 0.001) and to 8.9 ± 3.5 after 12 months (p = 0.051). The CST parameter Ambrósio's relational thickness to horizontal profile (ARTh) decreased statistically significantly from 229.9 ± 109.6 to 204.8 ± 84.9 at 6 months (p = 0.017) and 205.3 ± 93.7 at 12 months (p = 0.022). The CST parameter stiffness parameter A1 (SP A1) increased slightly from the preoperative value 69.9 ± 17.2 to 70.4 ± 17.2 after 6 months (p = 1) and 71 ± 18.2 after 1 year (p = 1). Mean best-corrected visual acuity (logMAR) showed an improvement from 0.39 ± 0.3 to 0.34 ± 0.3 at 6 months (p = 0.286) and to 0.31 ± 0.3 at 12 months (p = 0.077). Regarding the ABCD classification, the parameters were determined preoperatively with an average of A2B3C1D2. They showed the same value of A2B3C1D2 after 6 and 12 months. CONCLUSION In progressive keratoconus, corneal cross-linking has the potential to positively influence the biomechanics of the cornea and visual acuity as a low complication treatment option.
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Affiliation(s)
- S Feld
- Klinik für Augenheilkunde, Universitätsklinikum des Saarlandes (UKS), Kirrberger Str. 100, 66424, Homburg/Saar, Deutschland.
| | - E Flockerzi
- Klinik für Augenheilkunde, Universitätsklinikum des Saarlandes (UKS), Kirrberger Str. 100, 66424, Homburg/Saar, Deutschland
| | - L Daas
- Klinik für Augenheilkunde, Universitätsklinikum des Saarlandes (UKS), Kirrberger Str. 100, 66424, Homburg/Saar, Deutschland
| | - K Xanthopoulou
- Klinik für Augenheilkunde, Universitätsklinikum des Saarlandes (UKS), Kirrberger Str. 100, 66424, Homburg/Saar, Deutschland
| | - H Sideroudi
- Klinik für Augenheilkunde, Universitätsklinikum des Saarlandes (UKS), Kirrberger Str. 100, 66424, Homburg/Saar, Deutschland
| | - A Langenbucher
- Institut für Experimentelle Ophthalmologie, Universität des Saarlandes, Homburg/Saar, Deutschland
| | - B Seitz
- Klinik für Augenheilkunde, Universitätsklinikum des Saarlandes (UKS), Kirrberger Str. 100, 66424, Homburg/Saar, Deutschland
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Seifert FK, Theuersbacher J, Schwabe D, Lamm O, Hillenkamp J, Kampik D. Long-Term Outcome of Corneal Collagen Crosslinking with Riboflavin and UV-A Irradiation for Keratoconus. Curr Eye Res 2022; 47:1472-1478. [PMID: 36173395 DOI: 10.1080/02713683.2022.2117383] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
PURPOSE To evaluate long-term outcomes of corneal collagen crosslinking (CXL) using riboflavin and UV-A irradiation and to determine when to repeat CXL. METHODS In this retrospective consecutive interventional case series 131 eyes of 131 patients (95 male, 36 female, mean age 29.7 ± 11.4 years) between 2006 and 2016 received standard CXL (Dresden protocol, epithelium-off) for progressive keratoconus. Corrected distance visual acuity (CDVA) and corneal tomography (K1, K2, Kmax) were repeatedly recorded 1 year (n = 103 eyes) to 10 years (n = 44) postoperatively. Only one eye per patient was included. Paired t-test or Wilcoxon matched-pairs signed rank test was used for parametric and nonparametric data, respectively. RESULTS 1-3 years preoperatively, median K2 significantly increased by 1.1 D (p < 0.001). Postoperatively, median K2 increased by 0.1 D after 1 year, then decreased over the remaining postoperative period by 0.85 D (p = 0.021). Kmax fluctuated without significant change. Median apical corneal thickness decreased by 16 µm (p = 0.012) after 5 years and then returned to preoperative values. Mean CDVA showed a significant improvement (decrease in logMAR 0.08 after 10 years, p = 0.010). CXL non-responders, defined by a postoperative increase in Kmax>2 D, increased from 16% after 5 to 33% after 10 years. Risk factors for non-response were young age, high astigmatism (>4.3 D), thin cornea (<480 µm), poor initial visual acuity (CDVA ≥0.3 D), and atopic dermatitis. 4 eyes were re-treated 3-4 years after first CXL without complications and keratoconus stabilized thereafter. CONCLUSIONS CXL can slow or stop keratoconus progression. However, as the number of responders declines after 5 years, especially patients with risk factors may require re-treatment.
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Affiliation(s)
- Franziska K Seifert
- Department of Ophthalmology, University Hospital Wuerzburg, Wuerzburg, Germany
| | | | - Dorothee Schwabe
- Department of Ophthalmology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Olga Lamm
- Department of Ophthalmology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Jost Hillenkamp
- Department of Ophthalmology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Daniel Kampik
- Department of Ophthalmology, University Hospital Wuerzburg, Wuerzburg, Germany
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Gassel CJ, Röck D, Konrad EM, Blumenstock G, Bartz-Schmidt KU, Röck T. Impact of keratoconus stage on outcome after corneal crosslinking. BMC Ophthalmol 2022; 22:207. [PMID: 35524196 PMCID: PMC9077944 DOI: 10.1186/s12886-022-02425-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 04/22/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND This study aimed to analyze if the outcome after corneal crosslinking (CXL) in progressive keratoconus patients depends on the stage at which the procedure is performed. This knowledge would help to improve success of CXL and to define surgery indications in those patients. METHODS In this retrospective study, 124 consecutive eyes of 100 patients with progressive keratoconus undergoing corneal CXL at the University Eye Hospital Tübingen were included. The eyes were graded according to modified Krumeich stages depending on induced myopia or astigmatism, corneal radii, minimum corneal thickness, and morphological changes. The observation period covered November 2008 to September 2018. Preoperatively, 12 and 24 months after CXL, the best corrected visual acuity (BCVA) was determined and astigmatism as well as tomographic parameters (Kmax, Kmin, central corneal thickness (CCT), minimum corneal thickness (MCT)) were measured by means of a Scheimpflug camera system. RESULTS BCVA results showed significant differences between the modified Krumeich stages at 12 months (p = 0.014) and at 24 months postoperatively (p = 0.032). Also, astigmatism differed significantly among the stages at 24 months after CXL (p = 0.023). However, no significant differences regarding astigmatism were detectable after 12 months. In terms of Kmax, Kmin, CCT, and MCT, no significant differences between the Krumeich stages were observed. CONCLUSIONS BCVA showed a significantly higher improvement after CXL in the early stage of keratoconus compared to a higher stage. However, the postinterventional tomographic values did not differ significantly between the different modified Krumeich stages. The significantly higher improvement in BCVA after CXL in the early stage might indicate that earlier intervention provides a higher subjective benefit to the individual. Further studies with larger sample sizes are needed to confirm these findings.
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Affiliation(s)
- Caroline Julia Gassel
- Centre for Ophthalmology, University Eye Hospital, Eberhard Karls University Tübingen, Elfriede-Aulhorn-Str. 7, 72076, Tübingen, Germany
| | - Daniel Röck
- Centre for Ophthalmology, University Eye Hospital, Eberhard Karls University Tübingen, Elfriede-Aulhorn-Str. 7, 72076, Tübingen, Germany
| | - Eva-Maria Konrad
- Centre for Ophthalmology, University Eye Hospital, Eberhard Karls University Tübingen, Elfriede-Aulhorn-Str. 7, 72076, Tübingen, Germany
| | - Gunnar Blumenstock
- Institute for Clinical Epidemiology and Applied Biometry, Eberhard Karls University Tübingen, Silcherstr. 5, 72076, Tübingen, Germany
| | - Karl Ulrich Bartz-Schmidt
- Centre for Ophthalmology, University Eye Hospital, Eberhard Karls University Tübingen, Elfriede-Aulhorn-Str. 7, 72076, Tübingen, Germany
| | - Tobias Röck
- Centre for Ophthalmology, University Eye Hospital, Eberhard Karls University Tübingen, Elfriede-Aulhorn-Str. 7, 72076, Tübingen, Germany.
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Petrovic T, Stanojlovic S. Tomographic changes after corneal collagen cross-linking for progressive keratoconus - one-year follow-up study. SRP ARK CELOK LEK 2022. [DOI: 10.2298/sarh200731062p] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Introduction/Objective. The aim of this study was to evaluate the outcome of corneal collagen crosslinking (CXL) in patients with progressive keratoconus. Methods. This retrospective single-centered interventional study included 52 eyes of 41 patients who underwent epithelium-off CXL procedure at the age > 18 years. Corneal tomography data, uncorrected, and best spectacle-corrected distant visual acuity (UDVA and CDVA, respectively) were analyzed at baseline and postoperatively over the initial 12-month period. In addition, the natural course of corneal tomographic changes was demonstrated at one, three, six, nine, and 12 months after the CXL procedure. Results. At one year, mean UDVA improved significantly from 0.15 ? 0.22 (0.3 min ? logMAR ? 0 max logMAR) at baseline to 0.06 ? 0.09 logarithm of minimum angle resolution (logMAR) (0.1 min logMAR ? 0 max logMAR) (p = 0.024). Mean CDVA was 0.45 ? 0.39 0.45 ? 0.39 logMAR (0.8 min logMAR ? 0 max logMAR) at baseline and 0.06 ? 0.13 logMAR (1 min logMAR ? 0 max logMAR) at one year (p = 0.039). Maximum keratometry showed a significant flattening of 1.36 D ? 1.53 D (p = 0.0032) at one year after CXL. Minimum keratometry significantly decreased with a mean change of 1.15 ? 1.20 (p = 0.011). Mean anterior and posterior best fit sphere (ABFS and PBFS, respectively) remained stable during the entire follow-up period. Mean reduction of corneal thickness after CXL was 47 ? 61 ?m (p = 0.003). At one year, 29 (56%) eyes showed K max regression, 22 (53%) showed stabilization, and one (2%) showed progression. Spearman correlation coefficients were calculated to assess the correlation between difference in preoperative corneal thickness (CT), in posterior elevation corneal thickness (PECT), and minimum corneal thickness, ?CT (PECT ? minCT) and radius difference ?r (r1-r2). Spearman rs > 0.3 proved statistical significance and correlation. Conclusion. In our study, CXL effectively prevented progression of keratoconus in 98% of eyes at one year, while improving visual acuity. The effect of CXL can be evaluated at the earliest after six months; at that time, the stability of the corneal shape was provided by following the CXL procedure. The main limitation of this study is the small number of patients included.
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Affiliation(s)
- Tiana Petrovic
- University Clinical Center of Serbia, Clinic for Eye Diseases, Belgrade, Serbia
| | - Svetlana Stanojlovic
- University Clinical Center of Serbia, Clinic for Eye Diseases, Belgrade, Serbia + University of Belgrade, Faculty of Medicine, Belgrade, Serbia
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[Histological changes in keratoconus and wound healing after corneal cross-linking]. Ophthalmologe 2021; 119:342-349. [PMID: 34874483 DOI: 10.1007/s00347-021-01537-8] [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: 11/08/2021] [Indexed: 10/19/2022]
Abstract
BACKGROUND Keratoconus is classified as a corneal ectasia and is a multifactorial disease. In those affected, mostly adolescent patients visual deterioration occurs due to the development of irregular astigmatism. Treatment by corneal cross-linking (CXL) has been indicated in progressive disease for several years. OBJECTIVE To present the pathophysiology and histological changes in keratoconus as well as wound healing processes after CXL and their potential complications. MATERIAL AND METHODS Histological changes in keratoconus as well as wound healing processes after CXL and their potential complications are presented based on histological examination of corneal specimens with keratoconus with and without a condition after CXL. Relevant literature and own data are analyzed and discussed. RESULTS Besides inflammatory processes, atopic and genetic dispositions play a role in the development of keratoconus. The histological characteristics of keratoconus include changes in the epithelium, Bowman's layer and stroma. Wound healing processes after CXL include healing of the surface epithelium and transient loss of keratocytes and nerve fibers. CONCLUSION Keratoconus shows characteristic histopathological changes, such as epithelial irregularities, stromal thinning and breaks of Bowman's layer, whereas the endothelium and Descemet's membrane remain unchanged (apart from cases of corneal hydrops). After CXL wound healing processes can be followed primarily in vivo by confocal microscopy. Complications after CXL are rare. Persistent loss of keratocytes can be clinically manifested as a visually relevant scar.
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