title: Evaluation of corneal topographic changes and surgically induced astigmatism after transconjunctival 27-gauge microincision vitrectomy surgery.
abstract: OBJECTIVE
  To evaluate the corneal topographic changes and postvitrectomy astigmatism after 27-gauge (g) microincision vitrectomy surgery (MIVS) by using Pentacam HR-Scheimpflug imaging system.
  
  
  METHODS
  This prospective descriptive study included 30 eyes of 30 patients who underwent 27-g MIVS. All eyes underwent a Pentacam HR examination preoperatively and on the first week, first month and third month postoperatively. The power of the corneal astigmatism, mean keratometry (Km), K1and K2values and corneal asphericity (Q value) values for the both front and back surfaces of the cornea, index of surface variance (ISV), index of vertical asymmetry (IVA), index of height asymmetry (IHA), index of height decentration (IHD) and higher-order aberrations including coma, trefoil, spherical aberration, higher-order root-mean-square and total RMS were recorded. Additionally, the mean induced astigmatism was estimated by vector analysis.
  
  
  RESULTS
  No statistically significant changes were observed in the mean power of corneal astigmatism, mean keratometry, K1and K2values, corneal asphericity values, ISV, IVA, IHA, IHD and higher-order aberrations on the first week, first month and third month after the operation. The mean surgically induced astigmatism was calculated as 0.23 ± 0.11 D on the first week, 0.19 ± 0.10 D on the first month and 0.19 ± 0.08 D on the third month postoperatively.
  
  
  CONCLUSIONS
  Minor corneal surface and induced astigmatic changes are expected to result in rapid visual rehabilitation after pars plana vitrectomy with the 27-g MIVS system.
authors.affiliation: Ankara Ulucanlar Eye Training and Research Hospital, 06240, Ankara, Turkey. kemal_htepe@hotmail.com.
authors.forename: Kemal
authors.initials: K
authors.lastname: Tekin
authors.affiliation: Ankara Ulucanlar Eye Training and Research Hospital, 06240, Ankara, Turkey.
authors.forename: Kenan
authors.initials: K
authors.lastname: Sonmez
authors.affiliation: Ankara Ulucanlar Eye Training and Research Hospital, 06240, Ankara, Turkey.
authors.forename: Merve
authors.initials: M
authors.lastname: Inanc
authors.affiliation: Ankara Ulucanlar Eye Training and Research Hospital, 06240, Ankara, Turkey.
authors.forename: Kubra
authors.initials: K
authors.lastname: Ozdemir
authors.affiliation: Ankara Ulucanlar Eye Training and Research Hospital, 06240, Ankara, Turkey.
authors.forename: Yasin Sakir
authors.initials: YS
authors.lastname: Goker
authors.affiliation: Ankara Ulucanlar Eye Training and Research Hospital, 06240, Ankara, Turkey.
authors.forename: Pelin
authors.initials: P
authors.lastname: Yilmazbas
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001251:Astigmatism / Q000209:etiology / Q000473:pathology*; D019781:Corneal Topography; D057108:Corneal Wavefront Aberration / Q000209:etiology / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D011446:Prospective Studies; D013536:Suture Techniques; D014821:Vitrectomy / Q000009:adverse effects* / Q000379:methods*
keywords: Corneal topography; Induced astigmatism; Microincision vitrectomy surgery; Pars plana vitrectomy