| Part 1 Trends in research on corneal cross linking from 2001 to 2020: a bibliometric analysisBackgroundCorneal cross linking（CXL）is a treatment that can prevent or delay the progression of ectasia diseases such as keratoconus.A large number of articles on CXL research have been published in academic journals over the past few decades.Therefore,it is of utmost importance to explore the hotspots and trends in CXL research.PurposeThe purpose of this study was to map the publishing trend on CXL research and explore the research hotspots.MethodsA bibliometric analysis was used to analyze the CXL related literatures included in the Web of Science Core Collection.VOSviewer was used to build the knowledge map to visualize the number of annual publications,distribution of countries and institutions,international cooperation,author productivity,source journals and research hotspots in the field of CXL.ResultsA total of 2061 peer-reviewed articles on CXL research were collected from 2001 to2020,and the annual research production increased over time.The United States was the country with the largest number of published articles,and the University of Zurich was the most active institution.Hafezi F published the largest number of articles on CXL,while Cornea was the journal with the largest number of studies on CXL.The most frequently cited references mainly focus on CXL in the treatment of keratoconus.The keywords were divided in 5 categories: 1)CXL mechanism,2)ectasia diseases and refractive surgery,3)corneal biomechanics,4)efficacy evaluation,5)treatment of infectious keratitis.ConclusionThe quantity and quality of articles on CXL were evaluated using bibliometric techniques by extracting the data from the Web of Science Core Collection.The research hotspots could provide insights on CXL research,providing valuable information for clinicians to perform research in this field and find potential partners.Part 2 Accelerated epithelium-off corneal cross linking for pediatric keratoconusBackgroundAccelerated epithelium-off corneal cross linking（ACXL）has been used in the treatment of keratoconus in adults and children in recent years.Its efficacy in adults with keratoconus has been validated,but there are few studies on its application in children with keratoconus.PurposeThe purpose of this study was to evaluate the efficacy of ACXL in the treatment of keratoconus in children.MethodsFifty-seven eyes of 45 patients were included in this retrospective study.Patients who were diagnosed with keratoconus in our hospital from August 2018 to August 2021 and were younger than 18 years old at the time of ACXL were included.The postoperative follow-up period was from 0.5 to 2.4 years,and the results of preoperative and postoperative last follow-up examination were recorded,including corrected distance visual acuity（CDVA）,corneal endothelial cell density（ECD）,corneal morphological parameters and biomechanical parameters.Paired t-test or Wilcoxon rank test were used to analyze the related parameters before and after the last follow-up visit,and P <0.05 was considered statistically significant.ResultsThe mean age of patients at the time of ACXL was 15.8（14.4,17.3）（range: 10.8–17.9）years.Mean follow up was 1.1（0.9,1.4）years.There were no intraoperative or postoperative complications in ACXL.At the last postoperative examination of ACXL,the maximal keratometry（Kmax）decreased from 55.47（51.13,49.96）D to 55.20（51.05,59.06）D by significant difference（P=0.011）.The central corneal thickness（CCT）and thinnest corneal thickness（TCT）were 501.60±27.12μm and 484.98±26.52μm preoperatively,which decreased to 495.26±28.01μm and 476.32±29.91μm postoperatively by significant difference（P<0.05）.The applanation 1 time（A1T）was 6.83±0.28 ms preoperatively and increased to 7.11±0.24 ms postoperatively,the difference was statistically significant（P<0.001）.The maximum deflection amplitude（DAmax）was 1.03（0.97,1.13）mm preoperatively and decreased to 1.02（0.92,1.10）mm postoperatively,and the difference was statistically significant（P=0.015）.There were no significant changes in CDVA,ECD,flat keratometry（K1）,steep keratometry（K2）and stiffness parameter applanation 1（SPA1）（P > 0.05）.At the last follow-up visit,the incidence of pediatric keratoconus progression after ACXL was 14%（8 eyes）,and the effective rate of preventing keratoconus progression was 86%（49 eyes）.ConclusionACXL can effectively prevent the progression of keratoconus and increase corneal hardness in children,but its long-term effect needs further study and observation.Part 3 Accelerated transepithelial corneal cross linking for pediatric keratoconusBackgroundAccelerated transepithelial corneal cross linking（ATE-CXL）can maintain the integrity of the corneal epithelium and reduce the risk of postoperative infection,but there are few studies on its application in the treatment of pediatric keratoconus.PurposeThe purpose of this study was to evaluate the efficacy of ATE-CXL in the treatment of keratoconus in children.MethodsFifty-seven eyes of 45 patients were included in this retrospective study.Patients who were diagnosed with keratoconus in our hospital from August 2018 to August 2021 and were younger than 18 years old at the time of ATE-CXL were included.The postoperative follow-up period was from 0.5 to 3.0 years,and the results of preoperative and postoperative last follow-up examination were recorded,including CDVA,corneal ECD,corneal morphological parameters and biomechanical parameters.Paired t-test or Wilcoxon rank test were used to analyze the related parameters before and after the last follow-up visit,and P <0.05 was considered statistically significant.ResultsThe mean age of patients at the time of ATE-CXL was 15.8（13.8,17.3）（range: 8.9–17.9）years.Mean follow up was 1.1（0.8,1.5）years.There were no intraoperative or postoperative complications in ATE-CXL.At the last postoperative examination of ATECXL,the K1 increased from 49.70（46.25,52.85）D to 49.90（46.80,54.25）D by significant difference（P=0.012）.The CCT and TCT were 456.47±29.5μm and 428（410,443）μm preoperatively,which decreased to 453.00±29.64μm and 424（405.5,441）μm postoperatively by significant difference（P<0.05）.The A1 T was 6.70±0.24 ms preoperatively and increased to 6.91±0.24 ms postoperatively,the difference was statistically significant（P<0.001）.There were no significant changes in CDVA,ECD,K2,Kmax,SPA1 and DAmax（P > 0.05）.At the last follow-up visit,the incidence of pediatric keratoconus progression after ATE-CXL was 30%（17 eyes）,and the effective rate of preventing keratoconus progression was 70%（40 eyes）.ConclusionATE-CXL can effectively prevent the progression of keratoconus in children,but further studies with larger samples and longer follow-up are needed. |
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