Deciphering the Astigmatic Code in Libyan Keratoconus: From Epidemiological Trends to Clinical Precision

Abstract

Keratoconus is a progressive corneal ectasia that typically begins in adolescence, causing irregular astigmatism and visual impairment; in Libya, high consanguinity rates and intense ultraviolet exposure amplify its prevalence and severity, yet local epidemiological data have been lacking. This retrospective cross-sectional study mapped tomographic astigmatism in 1,824 eyes from 955 consecutive patients presenting to ophthalmic centers in Az-Zawiyah between August 2024 and August 2025, using the Sirius+ Scheimpflug-Placido topographer after excluding 86 eyes for incomplete data or other corneal abnormalities. Astigmatism correlated positively with keratoconus severity (rₛ = 0.278, p < 0.001), with each additional diopter increasing diagnostic odds by 83% (OR 1.83, 95% CI 1.68–1.99) and compounding to approximately 11-fold at +4.00 D above baseline; ROC analysis yielded AUC 0.736 (95% CI 0.705–0.768, p < 0.001), identifying -3.15 D as the threshold where manifest keratoconus probability becomes clinically dominant. These findings establish astigmatism as a practical triage tool in resource-limited settings, though its low sensitivity for subclinical disease underscores the need for combined other tomographic issues.