The association between bariatric surgery and cataract: a propensity score-matched cohort study

Background: Obesity is considered a risk factor for cataracts. The association between weight loss and a cataract among patients with obesity has not been assessed to date. Objectives: To assess the association between weight loss following bariatric surgery and cataracts. Setting: Nationwide Swedish healthcare registries between 2006 and 2019. Methods: We performed a population-based cohort study. Patients aged 40-79 years who underwent bariatric surgery were matched on their propensity score (PS) to up to 2 patients with obesity ("unexposed patients"). Cox proportional hazard regression analyses calculated hazard ratios (HRs) and 95% confidence intervals (CIs) of developing cataracts following bariatric surgery, compared with unexposed patients. Subgroup analyses by age, sex, bariatric surgery type, and duration of followup were conducted. Results: In total, 22,560 bariatric surgery patients were PS-matched to 35,523 unexposed patients. The risk of cataracts was decreased in bariatric surgery patients compared with unexposed patients (HR .71, 95% CI .66-.76). We observed the lowest risk of cataracts among bariatric surgery patients aged 40-49 years (HR .52, 95% CI .44-.75) but a null result for patients aged >60 years. Gastric bypass or duodenal switch were associated with decreased risks of cataracts, whereas sleeve gastrectomy yielded a null result. Subgroups of sex and duration of follow-up showed no evidence of effect modification (hazards were proportional throughout follow-up). Conclusion: Our results suggest that substantial weight loss following bariatric surgery is associated with a decreased risk of cataracts, especially if bariatric surgery was performed before age 60. (Surg Obes Relat Dis 2022;18:217-224.) (c) 2021 American Society for Bariatric Surgery. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).