Metabolic, Familial, and Environmental Factors Associated With Cataract in Young Bangladeshi Adults: A Hospital-Based Matched Case-Control Study.

Background Cataract is traditionally regarded as a disease of advanced age, but it is also encountered in young adults, in whom the metabolic and biochemical determinants of lens opacification remain poorly characterized. This study aimed to evaluate the sociodemographic, environmental, ocular, metabolic, and biochemical factors associated with cataracts in young Bangladeshi adults. Methods In this hospital-based matched case-control study, which was conducted at the National Institute of Ophthalmology and Hospital and the Department of Biochemistry, Dhaka Medical College, between July 2025 and June 2026, 40 adults with ophthalmologist-confirmed cataracts and 40 age- and sex-matched controls without lens opacity, drawn from patients attending the OPD of the same hospital for other eye complaints, were enrolled via purposive sampling. Exposures were recorded through structured face-to-face interviews, and fasting serum calcium (total calcium, not corrected for albumin), 25-hydroxyvitamin D, electrolytes, glucose, and lipid profiles were measured. Independent associations were estimated via multivariable logistic regression with Firth's penalized likelihood to reduce small-sample bias, followed by sensitivity analyses. Results Cases and controls had an identical mean age (37.4 ± 8.0 years) and sex distribution (23/40, 57.5% female in each group). Cataract was significantly associated with rural residence (16/40, 40.0% vs 4/40, 10.0%), biomass fuel use (28/40, 70.0% vs 14/40, 35.0%), diabetes mellitus (13/40, 32.5% vs 1/40, 2.5%), and family history of cataracts (21/40, 52.5% vs 5/40, 12.5%; all p < 0.01). Mean serum calcium, sodium, and potassium levels were lower, and fasting glucose levels were higher among cases (all p < 0.05). Hypocalcemia based on total serum calcium (13/40, 32.5% vs 3/40, 7.5%) and hypertriglyceridemia (21/40, 52.5% vs 8/40, 20.0%) were more common among cases, whereas vitamin D status and cholesterol fractions did not differ. After adjustment, hypocalcemia (adjusted OR (aOR) 17.64, 95% CI 3.08-147.60), diabetes mellitus (aOR 15.71, 95% CI 1.93-276.31), family history (aOR 11.76, 95% CI 2.77-69.20), hypertriglyceridemia (aOR 8.51, 95% CI 1.99-52.69), and rural residence (aOR 6.55, 95% CI 1.04-59.96) remained independently associated with cataracts, although CIs were wide, particularly for diabetes mellitus, reflecting the small sample size. The metabolic and familial associations persisted in all sensitivity analyses, including one restricted to urban participants, whereas the association with rural residence was of borderline significance in the main model and did not remain significant in any of the three sensitivity analyses in which it could be assessed; therefore, it should be interpreted cautiously. Conclusions Low total serum calcium (hypocalcemia), diabetes mellitus, family history of cataracts, and hypertriglyceridemia were independently associated with early-onset cataracts in young Bangladeshi adults. Without albumin correction or ionized calcium measurement, the hypocalcemia finding is preliminary. The association with rural residence was not robust in sensitivity analyses, possibly reflecting control selection. If confirmed, fasting glucose, serum calcium, and triglyceride levels may help identify young adults for closer eye examination. These case-control findings indicate associations, not causation, and require prospective confirmation.