People of Arabic ethnicity have a high rate of keratoconus (KC), according to a new study in the British Journal of Ophthalmology, which showed the highest rate of KC prevalence in this population compared to previous investigations.

The purpose of the study was to determine the prevalence of KC in Saudi children and adolescents between the ages of six and 21 in the region of Riyadh, Saudi Arabia (KSA) based on Scheimpflug corneal tomographic imaging.

Researchers enrolled 522 pediatric patients in this prospective, cross-sectional, observational, multicenter study. Two masked examiners established the diagnosis of KC using both objective and subjective screening criteria.

The first examiner found a KC prevalence rate of 5.56% (approximately one in 18 patients), and the second examiner reported a slightly lower rate of 3.83%  (approximately one in 26 patients). The study found only nine cases where the doctors disagreed on the diagnosis, but after further evaluation between the doctors, a consensus was obtained. Researchers noted the final KC prevalence was 4.79% or a ratio of 1:21 patients.

This study was unique in that it determined the diagnosis of KC based solely on masked examiners’ analysis of corneal imaging from modern screening technology, as opposed to previous studies that evaluated medical records or diagnostic codes from databases. Additionally, this study evaluated a young population that underwent medical consultation without any ophthalmological complaint or previous diagnosis.

With a prevalence of 4.79%, the results showed a drastic difference (a 95-fold increase) in the prevalence of KC when compared with earlier studies. This represents the highest rate reported to date, researchers noted.

Previous studies have shown the prevalence rate of KC in the Middle East is considerably higher than in other areas of the world, investigators said. Prior to this latest study, the highest rate reported was 3.30% (approximately one in 30 patients) from a population of medical students from Lebanon using Placido-based imaging. Another study, conducted in Israel, found a KC prevalence of 3.18% when analyzing 314 students with a mean age of 25 years.

“In conclusion, the prevalence of KC among children and adolescents of Saudi origin in the KSA is considerably higher than numbers reported from similar studies. This discrepancy might be due to geographical variations in disease prevalence and also to the use of modern large-scale corneal imaging in a pediatric population. Moreover, it raises the imminent question of a KC screening program in schools to improve the early detection and early adequate intervention,” researchers said.

Torres Netto EA, Al-Otaibi WM, Hafezi NL, et al. Prevalence of keratoconus in pediatric patients in Riyadh, Saudi Arabia. Br J Opthalmol. 2018 Oct;102(10):1436-41.