Proposed classification for topographic patterns seen after penetrating keratoplasty. Issue 4 (1st April 1999)

• Record Type: Journal Article
• Authors: Karabatsas, Constantinos H; Cook, Stuart D; Sparrow, John M
• Is Part Of: British journal of ophthalmology. Volume 83:Issue 4(1999)
• Page Start: 403
• Page End: 409
• Publication Date: 1999-04-01
• Subjects: keratoplasty -- corneal topography -- astigmatism; Ophthalmology -- Periodicals; 617.7
• DOI: 10.1136/bjo.83.4.403
• Languages: English
• ISSNs: 0007-1161

Abstract

Abstract : AIMS: 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.