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Transepithelial versus Epithelium-off Corneal Collagen Cross-linking for Corneal Ectasia: A Systematic Review and Meta-analysis.
Nath, S, Shen, C, Koziarz, A, Banfield, L, Nowrouzi-Kia, B, Fava, MA, Hodge, WG
Ophthalmology. 2021;(8):1150-1160
Abstract
TOPIC To evaluate the safety and efficacy of transepithelial corneal cross-linking in comparison with the established epithelium-off technique for corneal ectasia. CLINICAL RELEVANCE Considerable debate exists regarding whether transepithelial and epithelium-off cross-linking are comparable in their safety and efficacy. METHODS We searched 16 electronic databases, including Medline, Embase, Web of Science, and the grey literature, current to July 8, 2020, for randomized controlled trials comparing transepithelial and epithelium-off cross-linking for corneal ectasia. We excluded studies evaluating cross-linking for nonectatic indications, as well as non-randomized controlled trials. Our primary outcome was the change in maximal keratometry (Kmax) at 12 months after cross-linking, and we considered additional topographic, visual, and safety outcomes. We summarized our analyses by calculating weighted mean differences (MDs) with associated 95% confidence intervals (CIs) for continuous outcomes and relative risks (RRs) with corresponding 95% CIs for dichotomous outcomes. We conducted trial sequential analysis to determine whether the required information size was met for each outcome. The quality of individual trials was evaluated using the Cochrane Collaboration's risk of bias assessment tool, and the evidence was assessed at an outcome level using the Grading of Recommendations Assessment, Development, and Evaluation methodology. RESULTS Twelve studies totaling 966 eyes were eligible. A significant difference was found between transepithelial and epithelium-off cross-linking groups in the change in Kmax at 12 months (MD, 0.75; 95% CI, 0.23-1.28; P = 0.004; primary outcome) and at longest follow-up (MD, 1.20; 95% CI, 0.62-1.77; P < 0.001; secondary outcome) after treatment. No significant difference was found between the 2 groups when examining uncorrected distance visual acuity (MD, 0.04; 95% CI, -0.06 to 0.14; P = 0.386) or corrected distance visual acuity (MD, 0.01; 95% CI, -0.06 to 0.09; P = 0.732). Transepithelial cross-linking was associated with significantly fewer complications than the epithelium-off approach (RR, 0.22; 95% CI, 0.06-0.79; P = 0.020), although it was associated with an increased rate of disease progression at 12 months after treatment (RR, 4.49; 95% CI, 1.24-16.25; P = 0.022). The required information size was met for our primary outcome and trial sequential analysis supported the conventional meta-analysis. The quality of evidence was rated as moderate using the Grading of Recommendations Assessment, Development, and Evaluation methodology. DISCUSSION The efficacy of transepithelial cross-linking remains inferior to the epithelium-off approach, although it is significantly safer.
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Accelerated Versus Standard Corneal Cross-Linking for Progressive Keratoconus: A Meta-Analysis of Randomized Controlled Trials.
Kobashi, H, Tsubota, K
Cornea. 2020;(2):172-180
Abstract
PURPOSE To compare the clinical results of accelerated corneal collagen cross-linking (ACXL) to standard corneal collagen cross-linking (SCXL) in progressive keratoconus by summarizing randomized controlled trials using a meta-analysis. METHODS Trials meeting the selection criteria were quality appraised, and data were extracted by 2 independent authors. A comprehensive search was performed using the Cochrane methodology to evaluate the clinical outcomes of ACXL and SCXL for treating progressive keratoconus. Estimates were evaluated by weighted mean difference (WMD) and 95% confidence interval (CI) for absolute changes of the outcomes during 12-month observation periods. Postoperative demarcation line depth was also compared. RESULTS We identified 6 randomized controlled trials that met the eligibility criteria for this meta-analysis. SCXL resulted in a significantly better outcome in postoperative changes in best spectacle-corrected visual acuity (WMD = -0.02; 95% CI, -0.03 to -0.01; P < 0.0001); however, the small differences may not be clinically significant. ACXL provided a significantly better improvement of cylindrical refraction after the 1-year follow-up (WMD = 0.15; 95% CI, 0.05-0.26; P = 0.005). Demarcation line depth at 1 month after SCXL was deeper than that after ACXL (WMD = -102.25; 95% CI, -157.16 to -47.35; P = 0.0003). No differences in the changes in maximum keratometry, central corneal thickness, uncorrected visual acuity, spherical equivalent refraction, corneal biomechanical properties, and corneal endothelial cell density were found among both groups. CONCLUSIONS An ACXL shows a comparable efficacy and safety profile at the 1-year follow-up, but it has less impact on improving best spectacle-corrected visual acuity when compared with the Dresden protocol. Overall, both methods similarly stop the disease progression.
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Corneal collagen cross-linking for bacterial infectious keratitis.
Davis, SA, Bovelle, R, Han, G, Kwagyan, J
The Cochrane database of systematic reviews. 2020;(6):CD013001
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Abstract
BACKGROUND Infectious keratitis is an infection of the cornea that can be caused by bacteria, viruses, fungi, protozoa, or parasites. It may be associated with ocular surgery, trauma, contact lens wear, or conditions that cause deficiency or loss of corneal sensation, or suppression of the immune system, such as diabetes, chronic use of topical steroids, or immunomodulatory therapies. Photoactivated chromophore for collagen cross-linking (PACK-CXL) of the cornea is a therapy that has been successful in treating eye conditions such as keratoconus and corneal ectasia. More recently, PACK-CXL has been explored as a treatment option for infectious keratitis. OBJECTIVES To determine the comparative effectiveness and safety of PACK-CXL with standard therapy versus standard therapy alone for the treatment of bacterial keratitis. SEARCH METHODS We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2019, Issue 7); Ovid MEDLINE; Embase.com; PubMed; Latin American and Caribbean Health Science Information database (LILACS); ClinicalTrials.gov; and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP). We did not use any date or language restrictions in the electronic search for trials. We last searched the electronic databases on 8 July 2019. SELECTION CRITERIA We included randomized controlled trials (RCTs), quasi-RCTs, and controlled clinical trials (CCTs) of PACK-CXL for bacterial keratitis. We included quasi-RCTs and CCTs as we anticipated that there would not be many RCTs eligible for inclusion. DATA COLLECTION AND ANALYSIS Two review authors working independently selected studies for inclusion in the review, assessed trials for risk of bias, and extracted data. The primary outcome was proportion of participants with complete healing at four to eight weeks. Secondary outcomes included visual acuity, morphology, adverse events, and treatment failure at four to eight weeks. MAIN RESULTS We included three trials (two RCTs and one quasi-RCT) in this review for a total of 59 participants (59 eyes) with bacterial keratitis. Trials were all single-center and were conducted in Egypt, Iran, and Thailand between 2010 and 2014. It is very uncertain whether PACK-CXL with standard antibiotic therapy is more effective than standard antibiotic therapy alone for re-epithelialization and complete healing (risk ratio (RR) 1.53, 95% confidence interval (CI) 0.88 to 2.66; participants = 15). We judged the certainty of the evidence to be very low due to the small sample size and high risk of selection and performance bias. The high risk of selection bias reflects the overall review. Masking of participants was not possible for the surgical arm. No participant had a best-corrected visual acuity of 20/100 or better at eight weeks (very low certainty evidence). There is also no evidence that use of PACK-CXL with standard therapy results in fewer instances of treatment failure than standard therapy alone (RR 0.50, 95% CI 0.05 to 4.98; participants = 32). We judged the certainty of evidence to be low due to the small sample size and high risk of selection bias. There were no adverse events reported at 14 days (low certainty evidence). Data on other outcomes, such as visual acuity and morphological characteristics, could not be compared because of variable time points and specific metrics. AUTHORS' CONCLUSIONS The current evidence on the effectiveness of PACK-CXL for bacterial keratitis is of low certainty and clinically heterogenous in regard to outcomes. There are five ongoing RCTs enrolling 1136 participants that may provide better answers in the next update of this review. Any future research should include subgroup analyses based on etiology. A core outcomes set would benefit healthcare decision-makers in comparing and understanding study data.
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Effect of collagen supplementation on osteoarthritis symptoms: a meta-analysis of randomized placebo-controlled trials.
García-Coronado, JM, Martínez-Olvera, L, Elizondo-Omaña, RE, Acosta-Olivo, CA, Vilchez-Cavazos, F, Simental-Mendía, LE, Simental-Mendía, M
International orthopaedics. 2019;(3):531-538
Abstract
PURPOSE Osteoarthritis (OA) is one of the most common causes of disability and a prevalent chronic disease. The use of collagen is growing due to the satisfactory results in the treatment of OA. However, the possible beneficial effects of collagen for the treatment of OA are currently controversial. The aim of the present meta-analysis was to evaluate the effect of collagen-based supplements on OA symptoms. METHODS PubMed-Medline, Scopus, and Google Scholar databases were searched for randomized placebo-controlled trials evaluating the effect of orally administered collagen on OA symptoms using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scale and/or the Visual Analog Scale (VAS). Meta-analysis was conducted using a random-effects model and a generic inverse variance method. Heterogeneity was tested using the I2 statistic index. RESULTS Collagen treatment showed a significant reduction in the score of total WOMAC index (WMD - 8.00; 95% CI - 13.04, - 2.95; p = 0.002). After subgroup analysis of the WOMAC subscores, the collagen supplementation revealed a significant decrease in the stiffness subscore (WMD - 0.41; 95% CI - 0.74, - 0.08; p = 0.01), whereas the pain (WMD - 0.22; 95% CI - 1.58, 1.13; p = 0.75) and functional limitation (WMD - 0.62; 95% CI - 5.77, 4.52; p = 0.81) subscores did not have significant differences. Finally, a significant reduction was found in the VAS score after collagen administration (WMD - 16.57; 95% CI - 26.24, - 6.89; p < 0.001). CONCLUSION The results of this meta-analysis showed that collagen is effective in improving OA symptoms by the decrease of both total WOMAC index and VAS score.
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Comparison of Standard Versus Accelerated Corneal Collagen Cross-Linking for Keratoconus: A Meta-Analysis.
Wen, D, Li, Q, Song, B, Tu, R, Wang, Q, O'Brart, DPS, McAlinden, C, Huang, J
Investigative ophthalmology & visual science. 2018;(10):3920-3931
Abstract
PURPOSE To systematically compare epithelial-off standard (SCXL) to accelerated corneal collagen cross-linking (ACXL) for the treatment of keratoconus. METHODS PubMed, Embase, the Cochrane Library, and the US trial registry were searched for trials comparing SCXL and ACXL for keratoconus up to October 2017. Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated. Primary outcomes were changes in uncorrected distance visual acuity, maximum keratometry (Kmax), and mean keratometry (mean K). Secondary outcomes were changes in corrected distance visual acuity, mean refractive spherical equivalent, central corneal thickness (CCT), and endothelial cell density (ECD). RESULTS Eleven trials were included. For primary outcomes, SCXL showed a greater reduction in Kmax (SMD 0.32; 95% CI 0.16, 0.48) than ACXL. For secondary outcomes, the decrease in CCT (SMD 0.32; 95% CI 0.03, 0.61) and ECD (SMD 0.26; 95% CI 0.06, 0.46) was less with ACXL than with SCXL. For the other outcomes, there were no statistically significant differences. CONCLUSIONS SCXL has a greater effect in terms of reduction in Kmax than ACXL, while ACXL induces less reduction in CCT and ECD than SCXL. Further well-designed randomized controlled trials comparing ACXL and SCXL are indicated.
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Efficacy of Corneal Collagen Cross-Linking for the Treatment of Keratoconus: A Systematic Review and Meta-Analysis.
Meiri, Z, Keren, S, Rosenblatt, A, Sarig, T, Shenhav, L, Varssano, D
Cornea. 2016;(3):417-28
Abstract
PURPOSE To examine the efficacy of corneal collagen cross-linking (CXL) for the treatment of keratoconus (KCN). METHODS A systemic literature review and meta-analysis of ocular functional and structural parameters of patients with KCN undergoing cross-linking procedures were performed using PubMed and the web of science. A literature search was performed for relevant peer-reviewed publications on population-based studies. Data were analyzed with R software (Meta library), and heterogeneity was assessed with the Cochran Q and I. A random-effects model was used for high heterogeneity; otherwise a fixed model was used. Sensitivity analysis of particular tested groups was used to explain high heterogeneity. The main outcome measures extracted from the articles were corrected distance visual acuity, uncorrected distance visual acuity, and maximum K. RESULTS An improvement in visual acuity of 1 to 2 Snellen lines was found 3 months or more after undergoing CXL. Changes were more pronounced in uncorrected visual acuity. Some topography parameters were found to be improved (0.6-1 diopters) 12 to 24 months after CXL. The refractive cylinder improved by 0.4 to 0.7 diopters. Endothelial cell density decreased by 225 cells per square millimeter in the first 3 months and thereafter returned to normal. Corneal thickness was reduced by 10 to 20 μm in the year following CXL but not after 24 months. No changes in intraocular pressure were noted. CONCLUSIONS CXL is a safe and effective method for halting the deterioration of KCN, while slightly improving visual function.
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Corneal Collagen Cross-Linking for Infectious Keratitis: A Systematic Review and Meta-Analysis.
Papaioannou, L, Miligkos, M, Papathanassiou, M
Cornea. 2016;(1):62-71
Abstract
PURPOSE To assess the efficacy of corneal collagen cross-linking (CXL) in the management of infectious keratitis. METHODS Comprehensive literature search was performed in MEDLINE/PubMed and Cochrane Central Register of Controlled Trials using combinations of the following search terms: "corneal collagen cross linking" or "photoactivated riboflavin" or "UVA light and riboflavin" and "infectious keratitis" or "corneal ulcer." Last search was on March 19, 2015. Extracted data from individual studies were summarized and summary proportions of eyes healed and complications for different subgroups were estimated. RESULTS Twenty-five studies were included (2 randomized controlled trials, 13 case series, and 10 case reports) with a total of 210 eyes of 209 patients, of which 175 eyes underwent CXL. Causative microorganisms were bacteria, fungi, acanthamoeba, and Herpes simplex virus in 96, 32, 11, and 2 cases, respectively. Coinfections were present in 13 and cause was inconclusive in 21 cases. Sixteen of 175 eyes received no additional antibiotics, whereas 159 underwent CXL as an adjunct to antimicrobial treatment. Proportion of eyes healed with CXL was 87.2% (95% confidence interval (CI), 81.9%, 91.8%). For bacterial keratitis, the proportion of eyes healed was 85.7% (95% CI, 78.5%, 91.7%), whereas 10/11 and 25/32 eyes with acanthamoeba and fungal keratitis, respectively, were healed (available data not sufficient to provide a valid proportion analysis). Treatment resulted in corneal melting and tectonic keratoplasty in both Herpes simplex virus cases. CONCLUSIONS CXL seems promising in the management of infectious keratitis, excluding viral infections. However, more randomized controlled trials are required to assess its efficacy.