title: A comparison study of corneal topographic changes following 20-, 23-, and 25-G pars plana vitrectomy.
abstract: OBJECTIVE
  To evaluate and compare corneal topographic changes following pars plana vitrectomy with the 23-gauge (G) and 25-G transconjuntival sutureless vitrectomy system as well as the standard 20-G vitrectomy system.
  
  
  METHODS
  We prospectively evaluated corneal topographic changes in 45 eyes of 45 patients divided into three groups according to vitrectomy system used (20-, 23-, and 25-G). All patients underwent computer-assisted videokeratography using an EyeSys System 3000 topographer preoperatively and at one week, one month, and three months postoperatively.
  
  
  RESULTS
  In the 20-G vitrectomy group, we found statistically significant postoperative changes in corneal curvature parameters with an average steepening of 0.98 ± 0.18 D (P<0.001) and 0.93 ± 0.21 D (P<0.001) at one week and one month, respectively. No statistically significant difference was observed at the three-month follow-up visit. In the 23- and 25-G groups, no statistically significant changes in corneal curvature parameters were observed at any postoperative follow-up visit.
  
  
  CONCLUSIONS
  Twenty-three-gauge and 25-gauge transconjunctival sutureless vitrectomy did not induce topographic corneal changes following surgery, whereas 20-G vitrectomy was found to induce transient topographic corneal changes that had returned to preoperative levels at three months postoperatively.
authors.affiliation: Departamento de Oftalmo-Otorrinolaringologia, Universidade Federal do Paraná, Curitiba, PR, BR.
authors.forename: Alexandre Achille
authors.initials: AA
authors.lastname: Grandinetti
authors.affiliation: Departamento de Oftalmo-Otorrinolaringologia, Universidade Federal do Paraná, Curitiba, PR, BR.
authors.forename: Vinicius
authors.initials: V
authors.lastname: Kniggendorf
authors.affiliation: Departamento de Oftalmo-Otorrinolaringologia, Universidade Federal do Paraná, Curitiba, PR, BR.
authors.forename: Luciane Bugmann
authors.initials: LB
authors.lastname: Moreira
authors.affiliation: Departamento de Oftalmo-Otorrinolaringologia, Universidade Federal do Paraná, Curitiba, PR, BR.
authors.forename: Carlos Augusto
authors.initials: CA
authors.lastname: Moreira Junior
authors.affiliation: Departamento de Oftalmo-Otorrinolaringologia, Universidade Federal do Paraná, Curitiba, PR, BR.
authors.forename: Ana Tereza Ramos
authors.initials: AT
authors.lastname: Moreira
mesh_terms: D000328:Adult; D000368:Aged; D001251:Astigmatism / Q000209:etiology; D003315:Cornea / Q000473:pathology / Q000601:surgery*; D019781:Corneal Topography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D011184:Postoperative Period; D057234:Preoperative Period; D011446:Prospective Studies; D012016:Reference Values; D012164:Retinal Diseases / Q000209:etiology; D013536:Suture Techniques; D013997:Time Factors; D016896:Treatment Outcome; D014792:Visual Acuity; D014821:Vitrectomy / Q000009:adverse effects / Q000379:methods*