title: The influence of He-Ne laser on scar formation after trabeculectomy in rabbits.
abstract: OBJECTIVE
  To investigate the influence of He-Ne lasers on scar formation in the filtration canal after trabeculectomy in a rabbit model, as well as to explore the mechanisms for preventing scar formation when using He-Ne lasers in vivo.
  
  
  METHODS
  Experiment 1: Four groups were established (four eyes in each group). In 12 eyes, the upper nasal limbus area next to the upper rectus muscle received 10 minutes of He-Ne laser irradiation (100, 150, 200mW/cm(2); 60, 90, 120J/cm(2)) every day for three days. Four eyes served as controls. Twenty-four hours after the final irradiation, the rabbits were sacrificed and the irradiated tissue was excised, fixed with paraformaldehyde and tested for proliferating cell nuclear antigen (PCNA), connective tissue growth factor (CTGF) and apoptosis (TUNEL). Experiment 2: Forty-two rabbits were randomly divided into two groups and standard trabeculectomy was performed in the right eyes either after 200mW/cm(2) He-Ne laser irradiation or not in the filtration area. The expression of PCNA and CTGF, apoptosis and collagen density in the filtration area were tested on the 7(th), 14(th) and 28(th) day after surgery.
  
  
  RESULTS
  Experiment 1: There were no more PCNA and CTGF positive cells in the He-Ne irradiation group than in the control group. No apoptotic cells were found in either group. Experiment 2: The expression of PCNA and CTGF was lower in the He-Ne irradiation group than in the control group on the 7(th) and 14(th) day after trabeculectomy surgery (P<0.05); no apoptotic cells were detected in either group. Collagen density was significantly lower in the He-Ne irradiation group than in the control group on the 14(th) and 28(th) day after surgery (P<0.05).
  
  
  CONCLUSIONS
  Pretreating the filtration area with 200mW/cm(2) (120J/cm(2)) of He-Ne laser irradiation may be helpful in preventing scar formation after trabeculectomy, possibly due to the downregulation of the expression of PCNA, CTGF and collagen synthesis in fibroblasts.
authors.affiliation: Department of Ophthalmology, Tongji Hospital Affiliated to Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, Hubei Province, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Hu
authors.forename: Gui-Gang
authors.initials: GG
authors.lastname: Li
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.forename: Nan
authors.initials: N
authors.lastname: Xiang
authors.forename: Zhi-Qi
authors.initials: ZQ
authors.lastname: Chen
authors.forename: Rui-Lin
authors.initials: RL
authors.lastname: Wang
authors.forename: Yan
authors.initials: Y
authors.lastname: Xiang
authors.forename: Bin
authors.initials: B
authors.lastname: Li
authors.forename: Zheng-Jia
authors.initials: ZJ
authors.lastname: Li
authors.forename: Yan-Yan
authors.initials: YY
authors.lastname: He
authors.forename: Li-Fang
authors.initials: LF
authors.lastname: Wang