Prevalence of Keratoconus in Egyptian Subjects With High Corneal Astigmatism

Abstract Purpose: to determine the prevalence of keratoconus in subjects with astigmatism of two dioptres (2D) or greater using data from the Pentacam Scheimpflug images.Materials and Methods: This prospective cross-sectional study included 600 eyes of 600 patients with refractive errors aged ≥ 18 years who had no Present or past ocular pathology other than refractive error. Patients were equally divided into Group I (Patients with 2 diopters or greater of corneal astigmatism) and Group II (Patients with less than 2 corneal astigmatism).Results: the cylindrical refractive error among normal individuals in group I (high astigmatism) was -2.93 ± 0.89 ranging from -5.00 to -7.0, while that among keratoconus patients was -3.22 ± 1.17 ranging from to -2.00 to -8.00. No significant difference was found (P= 0.107). In group II (low astigmatism) the cylindrical refractive error among normal individuals was -0.7 ± 0.49 ranging from 0.0 to -2.0, while that among keratoconus patients was -0.75 ± 0.43 ranging from to 0.0 to 1.0. No significant difference was found (P= 0.65). It was found that among group I population (high astigmatism) 12.3% diagnosed as keratoconus patients, while 1.7% of group II (low astigmatism) were keratoconus patients. There was a highly significant difference between the two groups (P < 0.00001).Conclusions: The current study showed that subjects with 2D or more of astigmatism who present to outpatient clinics had higher prevalence of keratoconus than subjects with less than 2 D astigmatism. Therefore, it can be concluded that magnitude of astigmatism can be a risk factor for development of keratoconus.