title: Corneal hysteresis is correlated with reduction in axial length after trabeculectomy.
abstract: BACKGROUND
  We sought to determine whether corneal biomechanical parameters are predictive of reduction in axial length after anti-metabolite trabeculectomy.
  
  
  METHODS
  Chinese subjects undergoing trabeculectomy with mitomycin C by a single experienced surgeon underwent the following measurements: Corneal hysteresis (CH, Ocular Response Analyzer, Reichert Ophthalmic Instruments), Goldmann intra-ocular pressure (IOP), central corneal thickness (CCT) and axial length (AL, IOLMaster, Carl Zeiss Meditec, Dublin, CA) were measured pre-operatively, and AL, CH and IOP were measured 1 day and 1 week post-operatively.
  
  
  RESULTS
  Mean age of 31 subjects was 52.0 ± 15.2 years, and 15 (48.4%) were female. The mean pre-operative IOP of 21.4 ± 9.3 mmHg was reduced to 8.2 ± 4.6 mmHg 1 day and 11.0 ± 4.4 mmHg 1 week post-operatively (p < 0.001). AL declined from 22.99 ± 0.90 to 22.76 ± 0.87 mm at 1 day and 22.74 ± 0.9 mm at 1 week; 30/31 (%) eyes had a decline in AL (p < 0.001, sign test). In multivariate linear regression models including post-operative data from 1 day and 1 week, greater decline in Goldmann IOP (p < 0.0001, greater pre-op axial length (p < 0.001) and lower pre-operative CH (p = 0.03), were all associated with greater decline in post-operative axial length.
  
  
  CONCLUSIONS
  Eyes with lesser ability of the ocular coat to absorb energy (lower CH) had significantly greater decrease in axial length after trabeculectomy-induced IOP-lowering.
authors.affiliation: Joint Shantou International Eye Center of Shantou University and The Chinese University of Hong Kong, Shantou, Guangdong Province, China.
authors.forename: Chukai
authors.initials: C
authors.lastname: Huang
authors.forename: Mingzhi
authors.initials: M
authors.lastname: Zhang
authors.forename: Yuqiang
authors.initials: Y
authors.lastname: Huang
authors.forename: Bin
authors.initials: B
authors.lastname: Chen
authors.forename: Dennis S C
authors.initials: DS
authors.lastname: Lam
authors.forename: Nathan
authors.initials: N
authors.lastname: Congdon
mesh_terms: D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D003315:Cornea / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D005500:Follow-Up Studies; D005901:Glaucoma / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D013499:Surface Properties; D014065:Tonometry, Ocular; D014130:Trabeculectomy; D014463:Ultrasonography; D055815:Young Adult