title: Proposed classification for topographic patterns seen after penetrating keratoplasty.
abstract: OBJECTIVE
  To create a clinically useful classification for post-keratoplasty corneas based on corneal topography.
  
  
  METHODS
  A total of 360 topographic maps obtained with the TMS-1, from 95 eyes that had undergone penetrating keratoplasty (PKP), were reviewed independently by two examiners in a masked fashion, and were categorised according to a proposed classification scheme.
  
  
  RESULTS
  A high interobserver agreement (88% in the first categorisation) was achieved. At 12 months post-PKP, a regular astigmatic pattern was observed in 20/85 cases (24%). This was subclassified as oval in three cases (4%), oblate symmetric bow tie in six cases (7%), prolate asymmetric bow tie in six cases (7%), and oblate asymmetric bow tie in five cases (6%). An irregular astigmatic pattern was observed in 61/85 cases (72%), subclassified as prolate irregular in five cases (6%), oblate irregular in four cases (5%), mixed in seven cases (8%), steep/flat in 11 cases (13%), localised steepness in 16 cases (19%), and triple pattern in three cases (4%). Regular astigmatic patterns were associated with significantly higher astigmatism measurements. The surface asymmetry index was significantly lower in the regular astigmatic patterns.
  
  
  CONCLUSIONS
  In post-PKP corneas, the prevalence of irregular astigmatism is about double that of regular astigmatism, with a trend for increase of the irregular patterns over time.
authors.affiliation: Department of Ophthalmology, Bristol Eye Hospital.
authors.forename: C H
authors.initials: CH
authors.lastname: Karabatsas
authors.forename: S D
authors.initials: SD
authors.lastname: Cook
authors.forename: J M
authors.initials: JM
authors.lastname: Sparrow
mesh_terms: D001251:Astigmatism / Q000473:pathology; D003116:Color; D003316:Corneal Diseases / Q000473:pathology; D019781:Corneal Topography / Q000145:classification* / Q000379:methods; D006801:Humans; D015948:Keratoplasty, Penetrating / Q000379:methods*; D015588:Observer Variation; D011183:Postoperative Complications / Q000473:pathology*