Long-term Chronological Changes in Very Asymmetric Keratoconus

Purpose: To investigate chronological changes in patients with very asymmetric keratoconus (KC) by Scheimpflug-based corneal tomographic evaluation. Methods: We retrospectively reviewed the clinical records of 382 patients with KC attending a university hospital. Patients who were diagnosed with KC in one eye and forme fruste keratoconus in the other eye at the last visit and followed up with Scheimpflug-based tomographic corneal imaging were included. The anterior radius of curvature (ARC) and posterior radius of curvature (PRC) obtained at a 3.0-mm optical zone and the thinnest pachymetry reading of corneal thickness (Tmin), were used to investigate the chronological changes in tomographic parameters. Results: Twenty-six patients aged 16 to 66 years met the inclusion criteria. The mean observation period was 6 years and 4 months. There was a significant increase in annual change in PRC with a longer follow-up period after initial examination (P = 0.011). Moreover, a greater increase in annual change in ARC was observed in patients in whom the initial examination was performed at a younger age than in those in whom it was performed at an older age (P < 0.001). Conclusions: On the basis of tomographic evaluation, even if the measured values are almost stable and within normal limits, a long-term clinical follow-up is warranted in forme fruste keratoconus eyes. Younger patients with very asymmetric keratoconus should be monitored carefully.