Estimated prevalence of keratoconus in the largest metropolitan area of Italy

Purpose: To estimate the prevalence of keratoconus in a population of subjects undergoing first eye examination in an eye clinic in Italy. Methods: A single-center, cross-sectional, study was conducted involving patients who underwent first eye examination at an eye clinic in Rome between September 2021 and June 2022. The prevalence of keratoconus was determined by Placido-disk corneal topography using the maximum keratometry (Kmax) value and the Cone Magnitude and Location Index (CLMI) for keratoconus screening. Subjective analysis was performed by two experienced corneal specialists, who classified the outcome into two groups: normal and keratoconus. Risk factors, including family history of keratoconus, allergy or atopy, thyroid disease, eye rubbing habit and gender were also examined. Results: A total of 512 subjects between 7 and 81 years old were evaluated. The inter-observer agreement to classify subjects in normal or keratoconus group was excellent (k = 1.0); the estimated prevalence in the specific population was 2.1%. Presence of positive family history (9% of keratoconus vs 5% normal), concomitant allergy or atopy (27% vs 9%) and eye rubbing habit (18% vs 4%) were associated with a higher risk of disease. Conclusion: This study reported a high estimated prevalence of keratoconus in a metropolitan area of Italy, as found in recent studies in the Mediterranean and Middle East countries. Screening for keratoconus is highly recommendable and easily feasible with corneal topography under expert supervision and may be indicated primarily in young population to improve early detection and prompt therapeutic management for halting disease progression.