Abstract
Purpose:
Keratoconus is a congenital, progressive, ecstatic disease of the cornea. However, the mechanism of exacerbation is unclear. We retrospectively analyzed the characteristics of keratoconus patients to identify predictors of disease progression.
Methods:
This study retrospectively analyzed 55 eyes of 35 patients (10 females and 25 males; age, 25.3±8.0 years) with keratoconus, who were followed for at least 6 months at our institute. In addition to standard ophthalmic examinations, we investigated the change in manifest refraction (spherical equivalents [SE] and cylinder power [Cyl]), steepest keratometric value (Ks), and thinnest corneal thickness (TCT). We also asked the age at which the patients were diagnosed with keratoconus. We defined progression as a decrease of more than 0.5 diopters per year (D/Y) for SE and increases of 0.5 D/Y for Cyl and Ks. We assigned progression scores from 0 to 3 as follows: 0, no progression observed for SE, Cyl, and Ks; 1, one of the factors progressed; 2, two factors progressed; and 3, all three factors progressed.
Results:
The age at diagnosis ranged from 14 to 41 years. At the first visit, SE, Cyl, Ks, and TCT were -4.41±4.24 D, -3.05±2.01 D, 50.42±7.25 D, and 451.7 ± 62.1 µm, respectively. SE progressed - 0.95 ± 5.93 D/Y, Cyl increased 0.44 ± 3.07 D/Y, the steepest K-value increased 0.44 ± 3.07 D/Y, and the TCT decreased 4.45 ± 18.08 µm per year. Spearman’s rank correlation test showed that the rates of change of SE, Cyl, and the progression score were correlated with the change in TCT (ρ = 0.3375, 0.3816, and -0.331; p = 0.0165, -0.0063, and 0.0189, respectively). Ks was correlated with the rate of change of Cyl (ρ = 0.3012, p = 0.0269). The rate of change of Ks was correlated with patient age at the first visit (ρ = -0.2845, p = 0.039).
Conclusions:
A thin, steep cornea may help to predict the progression of keratoconus. Particularly, the decrease in corneal thickness is an important indicator of progression; however, patient age could be a secondary factor.
Keywords: 574 keratoconus •
464 clinical (human) or epidemiologic studies: risk factor assessment •
479 cornea: clinical science