Prevalence and risk factors for keratoconus in a university-based population in Turkey

PURPOSE This study aimed to determine the prevalence of keratoconus (KC) in the students and faculty members (aged ≥18 and ≤30 years) studying/working at the Medical and Health Sciences faculties of Eskisehir Osmangazi University. SETTING Eskisehir Osmangazi University. DESIGN Prevalence study. METHODS Subjects were randomly selected to undergo KC screening using a proportional stratified sampling method. Out of the 648 invited subjects, 585 (90.3%) responded to the invitation. The demographic data, medical/family history and habits of the subjects were collected using a standardized questionnaire. Subjects were classified as KC, ectasia susceptibility, and normal based on the corneal tomography. The chi-square and Kruskal-Wallis tests were used for the analysis of categorical variables and parametric values, respectively. Risk factors for KC were determined using logistic regression analysis. RESULTS The prevalence of KC was 2,393/100,000 (2.4%, 95% CI: 1.3%-4%), whereas that of ectasia susceptibility was 1,538/100,000 (1.5%, 95% CI: 0.7%-2.9%). Although the prevalence was much higher in male (4%, 95% CI: 1.7%-7.7%) than in female (1.6%, 95% CI: 1.1%-4.4%) the difference was not statistically significant (p=0.09). The majority (78.6%, n=11) of KC patients were unaware of their disease. Eye rubbing (OR:3.53, p=0.024) and consanguineous marriage (OR:12.87, p=0.032) were independent risk factors for KC. CONCLUSION This is the first population-based KC prevalence study in a randomized sample conducted in Turkey. The prevalence of KC in Turkey was much higher than in European countries but similar to neighboring countries in the Middle East. Eye rubbing and history of consanguineous marriage were significant risk factors.