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

ABSTRACT 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. Objective 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 two 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 to unexposed patients. Subgroup analyses by age, sex, bariatric surgery type, and duration of follow-up 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 to unexposed patients (HR 0.71, 95% CI 0.66-0.76). We observed the lowest risk of cataracts among bariatric surgery patients aged 40-49 years (HR 0.52, 95% CI 0.44-0.75) 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 and relevance 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.