Impact of Metabolic Syndrome on Cataracts: A Systematic Review and Meta-Analysis

Cataracts are the leading cause of blindness worldwide. Obesity, a key component of metabolic syndrome (MetS), may represent a modifiable risk factor for cataracts. However, the evidence regarding the association between MetS or its components and cataracts remains controversial. Therefore, our meta-analysis aims to clarify the relationship between MetS or its components and cataracts. A search was conducted until February 2024 via the MEDLINE, EMBASE, and Cochrane databases. The primary endpoint included the association between MetS or its components, including body mass index (BMI), diabetes mellitus (DM), hypertension (HT), and dyslipidemia (DLP), and cataracts. Secondary endpoints included the association between levels of blood pressure, blood sugar, and lipid profiles and cataracts. A total of 27 studies were included with a total of 1,010,014 patients (134,498 with cataracts and 875,516 without cataracts). Of these, there were 2 prospective cohort studies, 6 case-control studies, and 19 cross-sectional studies. The prevalence of cataracts was 13.3%. MetS was significantly associated with cataracts with an odds ratio (OR) of 1.60 (95% confidence interval [CI]: 1.44-1.77, I² = 93%). Among MetS components, high BMI and being diagnosed with DM, HT, and DLP were associated with cataracts with ORs of 1.45 (95% CI: 1.33-1.58, I² = 80%), 1.77 (95% CI: 1.69-1.85, I² = 51%), 1.23 (95% CI: 1.19-1.28, I² = 62%), and 1.38 (95% CI: 1.30-1.46, I² = 0%). Among the metabolic parameters, high total cholesterol, high triglycerides, low high-density lipoprotein cholesterol, and high low-density lipoprotein cholesterol were associated with cataracts with ORs of 1.25 (95% CI: 1.04-1.49, I² = 48%), 1.05 (95% CI: 1.04-1.06, I² = 68%), 1.07 (95% CI: 1.01-1.13, I² = 0%), and 1.30 (95% CI: 1.10-1.53, I² = 71%), respectively. MetS, obesity, DM, HT, and DLP are associated with cataracts. Prevention or treatment of MetS or its components likely represent a modifiable risk factor in cataract development.