Epidemiology of keratoconus in an Iranian population.

PURPOSE

To determine the incidence of clinical keratoconus (KCN) in an Iranian population.

METHODS

This prospective surveillance study was conducted in Yazd province in central Iran (population 990,818). During 1 year (July 2008 to June 2009), all new patients with KCN were registered and referred. Diagnosis was based on the topographic pattern, and indices were measured and eye examination was done by anterior segment subspecialists.

RESULTS

Of the 564 eligible patients referred, 28 did not attend their topography session (95% response rate). Topographic figures showed suspect or definite patterns of KCN in 47.8% of participants (256/536 subjects). Based on topographic images and clinical examination, KCN was confirmed in 221 patients, and in addition, 26 patients were categorized as having suspected KCN and 9 had non-KCN corneal diseases; therefore, the annual incidence rate of KCN was estimated as 22.3 (95% confidence interval, 19.5-25.4) and 24.9 (95% confidence interval, 21.9-28.2) per 100,000 population, excluding and including suspected KCN cases, respectively.

CONCLUSION

The incidence of KCN in our context is apparent and comparable with rates in other studies on Asian ethnic populations. This is much higher than the incidence in European Caucasians and warrants further genetic and environmental studies.