Abstract

P 139

Pachymetry profile analysis for diagnosis of keratoconus and pellucid marginal degeneration

Jens Bühren, Daniela-Luise Ott, Oliver Klaproth, Thomas Kohnen
Klinik für Augenheilkunde, Klinikum der Johann Wolfgang Goethe-Universität, Frankfurt/Main

Objective
The goal of the study was the evaluation of corneal pachymetric profile analysis to discriminate between eyes with keratoconus (KC), pellucid marginal degeneration (PMD) and normal eyes.
Methods
In a retrospective study, 55 eyes (32 patients) with KC, 60 eyes (43 patients with PMD) and 64 normal eyes (32 patients) were included. Corneal pachymetric tomography was performed using Scheimpflug photography. From pachymetric data obtained along 15 meridians centered to the thinnest point (0,2 mm steps; maximum radius r 4,4 mm), the percentual thickness increase relative to the thinnest point and the slopes along the meridians were computed. Discriminative ability of different parameters was assessed using Receiver Operating Charakteristic (ROC) analysis.
Results
Comparing KC with normal eyes, the maxima of percentage thickness increase between 2.1 und 3.8 mm distance from the thinnest point showed highest discrimnative ability (standardised area under the ROC curve – AzROC=0.915 to 0.947). Differentiation between PMD und normal eyes was best with maxima of percentage increase measured at 1.05 mm distance from the thinnest point (AzROC=0.934). For discrimnation of KK from PMD, minima and medians of the slope between 2.1 und 3.8 mm distance from the thinnest point (AzROC=0.661 bis 0.706).
Conclusions
Corneal pachymetric profile analysis is useful to differentiate between KC, PMD and normal eyes. Percentage increase values relative to the thinnest point showed highest discriminative ability. However, discriminative ability of PMD from KC eyes could be improved.

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