The Association Between Keratoconus and Body Mass Index: A Population-Based Cross-Sectional Study Among Half a Million Adolescents.

PURPOSE: To analyze the association between keratoconus and body mass index (BMI) among adolescents.

DESIGN

Cross sectional study.

METHODS

This was a nationwide, population-based study of candidates for military service in Israel attending the draft board in 2006 to 2014 who underwent an ophthalmologic examination. The study population included 579,946 males and females between 16 and 19.9 years of age. Subjects were divided into 4 groups based on adjusted BMI percentiles: underweight (8.3%), normal weight (73.9%), overweight (10.7%), and obese (7.1%). The odds for having keratoconus were compared with the normal weight group. The primary outcome measure was the odds ratio (OR) for the association between BMI groups and keratoconus.

RESULTS

The prevalence of keratoconus in the general population was 164 cases per 100,000, increasing over time (P < .05). There was a greater prevalence of keratoconus among obese adolescents (270/100,000) than of overweight (179/100,000), normal weight (154/100,000), and underweight (141/100,000) adolescents. Compared with the normal weight group, the OR for obese adolescents was 1.50 (95% confidence interval [CI] 1.22-1.83; P < .05), the OR for overweight adolescents was 1.42 (95% CI 1.08-1.92; P < .05), and the OR for underweight adolescents was 0.84 (95% CI 0.65-1.09; P = .18) after adjustment for gender, age, height, country of origin, and socioeconomic status.

CONCLUSIONS

This study provides strong evidence regarding the independent association between BMI and keratoconus. Overweight and obese adolescents have higher odds of having keratoconus compared with normal weight adolescents. BMI should be considered a risk factor for keratoconus and further research should elucidate how obesity is involved in the progress of keratoconus.