Topographic Progression of Keratoconus in the Korean Population

PURPOSE To develop a criterion for determining the topographic progression of keratoconus and to analyze the prognostic factors of progression. METHODS Medical records of 211 eyes of 128 patients who had been followed up for more than 2 years on three or more occasions were retrospectively reviewed. Topographic parameters, including simulated K, corneal astigmatism, irregular astigmatism at 3 and 5 mm, thinnest-point pachymetry, anterior and posterior elevation, and inferior minus superior index, were used to determine topographic progression. Topographic progression was determined by the greatest kappa value associated with progression to corneal graft surgery. Eyes were separated into progressed and non-progressed groups on the basis of topographic progression. The association of clinical factors with topographic progression, including demographic factors, contact lens use, corneal erosion, and atopic history at the time of diagnosis, was assessed by logistic regression. RESULTS When topographic progression was defined as five or more progressed topographic parameters, the greatest kappa value (0.354) was obtained. Ninety-four of the 211 keratoconic eyes (44.5%) were identified as topographically progressed. Age at diagnosis was significantly different between the progressed and non-progressed groups (22.2 vs. 24.7 years, p = 0.014). Logistic regression revealed that younger age at diagnosis was a risk factor for topographic progression (odds ratio, 0.948; 95% confidence interval, 0.907 to 0.991; p = 0.010). CONCLUSIONS We developed a criterion for evaluating topographic progression of keratoconus using diverse topographic indices. Younger age at diagnosis was associated with topographic progression of keratoconus.