Population study: Keratoconus prevalent in adolescents with overweight, obesity
Keratoconus is more likely in adolescents with overweight or obesity than in their normal and underweight counterparts, according to an Israeli population study published in the American Journal of Ophthalmology.
“Israeli adolescents recruited for mandatory military service undergo a medical and cognitive assessment at mean age of 17 years,” Adiel Barak, MD, of the department of ophthalmology at Tel Aviv Sourasky Medical Center and Sackler Faculty of Medicine at Tel Aviv University in Israel, told Healio/OSN. “We have already published results of long-term changes in myopia, association of cognitive function and myopia and effect of education on myopia. During our analysis, we have found that the subgroup of recruits with keratoconus deserve our analysis, thus we turn our attention to this group and analyzed our data set for recruits with keratoconus.”
Barak and colleagues conducted a nationwide, population-based, cross-sectional study of the 579,946 candidates for military service in Israel who had an ophthalmological exam. Candidates were aged 16 to 19.9 years. They divided candidates into BMI-based quartiles, which included underweight (8.3%), normal weight (73.9%), overweight (10.7%) and obese (7.1%). The main outcome measure was the odds ratio for the association between BMI and keratoconus.
The general prevalence of keratoconus was 164 cases per 100,000 candidates and increased over time (P < .05) in all quartiles. From 2006 to 2014, overall prevalence of keratoconus increased 177%.
“The marked increase in prevalence over a relatively short period” was surprising, Barak said. “One can attribute the results to better detection, but in our study group the same tests were done over time and still there was big increase in prevalence in all groups examined. We have no clear answer why such increase is happening.”
Another unexpected finding was the strong association between BMI and keratoconus, Barak said.
There was greatest prevalence and odds for keratoconus among adolescents with obesity (prevalence, 270 per 100,000; OR = 1.50; 95% CI, 1.22-1.83), followed by adolescents with overweight (prevalence, 179 per 100,000; OR = 1.42; 95% CI, 1.08-1.92) and adolescents with underweight (prevalence, 141 per 100,000; OR = 0.84; 95% CI, 0.65-1.09) compared with adolescents with normal weight (prevalence, 154 per 100,000).
The analysis was adjusted for gender, age, height, country of origin and socioeconomic status.
“We did speculate that higher BMI may be connected to keratoconus, but not such striking evidence,” Barak said. “Our findings of the strong independent association of obesity and keratoconus have never been reported and was certainly a surprise we did not anticipate.”