Correlation of Anterior Segment Parameters in Keratoconus Patients

Purpose: To evaluate the corneal asphericity, volume, thickness and keratometry and the correlation among these variables in keratoconus patients. Materials and methods: A total of 1,071 eyes of 810 patients diagnosed with keratoconus were evaluated with a Pentacam (Oculus Optikgerate GmbH). Five groups were established according to the mean keratometry readings: Very mild [K < 44.0 diopters (D)], mild (K = 44.0-47.0D), moderate (K = 47.0-52.0D), severe (K = 52.0-60.0D) and very severe (K = 60.0 or higher). The following parameters were obtained: Anterior corneal asphericity (Q), corneal volume (CV) and thinnest corneal thickness (TCT). Results: Sixty-six eyes had very mild keratoconus, 269 had mild keratoconus, 465 had moderate keratoconus, 233 had severe keratoconus and 38 had very severe keratoconus. As the severity of disease increases, there is an increment in K and CV values and reduction of Q and TCT. There was a statistically significant difference in values for all parameters, except the CV. The Pearson correlation index showed an inverse correlation between the degree of keratoconus and the asphericity (Q), i.e. the more severe the keratoconus the more negative the Q-value. Only in the very severe group there was no statistically significant correlation between K and Q. There was no correlation between severity of keratoconus and CV. There was an inverse correlation between keratoconus grade and TCT; the more advanced the disease the less the TCT value. Only in the very mild group there was no correlation between K and TCT. Conclusion: The corneal asphericity and pachymetry are inversely correlated to keratometry in keratoconus patients. There is no correlation between CV and severity of keratoconus.