title: Comparison of central corneal thickness using ultrasound pachymetry during corneal collagen cross-linking.
abstract: OBJECTIVE
  To study variation in central corneal thickness (CCT) during corneal collagen cross-linking(CXL) using ultrasound pachymetry.
  
  
  METHODS
  Twenty patients (26 eyes) with progressing keratoconus undergoing riboflavin-UVA-induced CXL were involved in this study. Intraoperative CCT measurement using ultrasonic pachymetry was performed during the procedure. Measurements were obtained before operation, after epithelial removal, after riboflavin drop instillation, and after UVA irradiation.
  
  
  RESULTS
  Mean CCT was 495 +/- 56 and 450 +/- 52 microm before and after epithelial removal, respectively. Mean CCT was 443 +/- 42 and 411 +/- 39 microm after riboflavin drop instillation and after UVA irradiation, respectively. Statistically significant decreases in CCT occurred between the preoperative period and after epithelial removal, after riboflavin drop instillation and after UVA irradiation. Twenty-six eyes from 20 patients undergoing CXL were divided into 2 groups (I with CCT > or = 400 microm after UVA irradiation and II with CCT < 400 microm after UVA irradiation). No statistically significant difference was noted between I and II in preoperative endothelial cell count, but a statistically greater postoperative endothelial cell count was noted in I compared to II. A statistically significant difference was evident between preoperative and postoperative endothelial cell counts in Group II (P < 0.05).
  
  
  CONCLUSIONS
  Performing CXL with the use of riboflavin and UVA irradiation resulted in a statistically significant decrease in CCT, to a level where the corneal endothelium may be damaged.
authors.affiliation: Cadet Corps, Postgraduate Medical School, PLA General Hospital, Beijing 100853, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Pang
authors.affiliation: Department of Ophthalmology, Navy General Hospital, Beijing 100048, China.
authors.forename: Xiujun
authors.initials: X
authors.lastname: Peng
authors.affiliation: Department of Ophthalmology, Navy General Hospital, Beijing 100048, China.
authors.forename: Zhengjun
authors.initials: Z
authors.lastname: Fan
authors.affiliation: Department of Ophthalmology, Navy General Hospital, Beijing 100048, China.
authors.forename: Hongzhen
authors.initials: H
authors.lastname: Jia
authors.affiliation: Department of Ophthalmology, Navy General Hospital, Beijing 100048, China.
authors.forename: Tengfei
authors.initials: T
authors.lastname: Wu
mesh_terms: D003094:Collagen / Q000187:drug effects / Q000528:radiation effects; D003315:Cornea / Q000000981:diagnostic imaging / Q000187:drug effects / Q000528:radiation effects; D063171:Corneal Pachymetry / Q000379:methods*; D003319:Corneal Stroma / Q000000981:diagnostic imaging* / Q000187:drug effects / Q000528:radiation effects; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D004728:Endothelium, Corneal / Q000187:drug effects / Q000528:radiation effects; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000000981:diagnostic imaging / Q000188:drug therapy*; D008297:Male; D011446:Prospective Studies; D012256:Riboflavin / Q000627:therapeutic use*; D014463:Ultrasonography; D014466:Ultraviolet Rays / Q000009:adverse effects
chemical_list: D003432:Cross-Linking Reagents; D003094:Collagen; D012256:Riboflavin