Longitudinal Evaluation of the Progression of Keratoconus Using a Novel Progression Display

Objectives: To evaluate the longitudinal tomographic changes and to compare the discriminatory potential of a novel progression display between progressive and nonprogressive keratoconic eyes. Methods: Retrospective evaluation was made of 81 eyes of 81 patients with keratoconus who had undergone Scheimpflug measurements at least twice with an interval of 12 months or longer between each measurement. The progressive group was defined as 36 eyes, which showed progression according to the definition of the global consensus on keratoconus and ectatic diseases when 2 of the 3 criteria were met, and the other 45 eyes were considered the nonprogressive group. The main outcome measures from progression display were A for anterior radius of curvature, B for posterior radius of curvature, C for thinnest pachymetry, D for distance visual acuity; K-max; Q-value front and back; index of surface variance (ISV), vertical asymmetry, height asymmetry, and height decentration; overall deviation of normality (final D); average pachymetric progression index; and maximum Ambrosio relational thickness. Results: The rate of change per year of A, B, C, thinnest pachymetry, K-max, final D, and ISV was significantly different between groups (P <= 0.01 for all values). It was determined that yearly change rates greater than 0.12 for A, 0.14 for B, 10.04 mm for thinnest pachymetry, 0.68 D for K-max, 0.15 for final D, and 2.11 for ISV might indicate progression in keratoconus management. Conclusions: Belin progression display parameters may be useful in discriminating progressive from nonprogressive keratoconic eyes.