Table 1.

Characteristics of studies included in the systematic review (n = 15).

Study	Country	Design/study period	Data source/population	Study/analysis N (cataract cases/events)	Age	Follow-up	Cataract outcome ascertainment	Exposure assessment	Air-pollution exposure(s)	Effect measure	Main covariate adjustment
Choi et al. (2018) (26)	South Korea	Population-based cross-sectional; 2008–2012	KNHANES IV–V; Adults >40 years	19,910 (10,085)	58.9 ± 12.0 years	Not applicable	Ophthalmologist slit-lamp examination; LOCS III; prior cataract surgery counted as cataract-positive	Ambient monitoring data from Korea Ministry of Environment; 283 monitoring stations; exposure assigned at 16 administrative-division level	NO2, O3, PM10, SO2	OR	Age, sex, residence, education, income, sun exposure, smoking, alcohol, hypertension, diabetes, hypercholesterolemia, myopia, obesity
Shin et al. (2020)a (24)	South Korea	Nationwide population-based retrospective cohort study; Baseline/washout 2002–2003; incident outcome follow-up 1 Jan 2004–31 Dec 2015	Korean National Health Insurance Service–National Sample Cohort (NHIS–NSC); Adults aged ≥50 years in 2002, cataract-free during 2002–2003, with stable/matched residence and smoking data	115,728 (16,814)	Mean 60.0 ± 7.2 years	Up to 12 years (2004–2015)	New cataract required both physician diagnosis (ICD-10 H25/H26) and cataract surgery code S5119; participants with cataract diagnosis in 2002–2003 were excluded. Index date was first cataract diagnosis.	Residential-area exposure matched to 268 nationwide surveillance stations using five-digit residence codes. Hourly monitoring data were summarized as average concentrations and categorized into quartiles. PM10/NO2/CO/SO2/O3 were available from 2002 to 2015; PM2.5 was available only for 2015.	CO, NO2, O3, PM10, PM2.5, SO2	HR	Age, sex, smoking status, income/insurance level, urbanization, and comorbidity
Chua et al. (2021)a (23)	United Kingdom	Prospective observational cohort; Baseline 2006–2010; follow-up to 31 Mar 2017	UK Biobank participants aged 40–69 at enrollment; baseline cataract and early/pre-2011 surgery excluded	433,727 (16,307)	Not reported overall; cases 62.5 ± 5.6, controls 56.0 ± 8.1 years	Mean 94 ± 15 months (7.8 years)	Incident first-eye cataract surgery via NHS linkage; OPCS-4 C71.2 (phacoemulsification) or C75.1 (lens replacement). Excluded baseline cataract, surgery within 1 year of baseline, and surgery in 2010 or earlier.	ESCAPE land-use regression at baseline residential address using GIS predictors. NO2 averaged 2005/2006/2007/2010; PM10 averaged 2007/2010; PM2.5, PM2.5-10, PM2.5 absorbance and NOx based on 2010 estimates.	NO2, NOx, PM10, PM2.5, PM2.5 absorbance (black carbon proxy), PM2.5–10	HR	Age, sex, race, Townsend deprivation index, BMI, smoking status, diabetes
Grant et al. (2021) (20)	Canada	Cross-sectional analysis of baseline cohort data; Baseline assessments Dec 2011–Jul 2015	Canadian Longitudinal Study on Aging (CLSA) Comprehensive Cohort; Community-dwelling adults aged 45–85 years near 11 CLSA data collection sites in 7 Canadian provinces	29,147 (8,286)b	Not reported	Not applicable	Self-reported prior physician diagnosis of cataract at baseline	Annual mean ambient pollutants assigned to participant postal code through CANUE. PM2.5 was satellite-derived (AOD + GEOS-Chem) calibrated to ground observations; O3 from Environment and Climate Change Canada air-quality modelling; SO2 from OMI satellite/GEM profiles; NO2 from national monitoring plus land-use regression/local gradients.	O3, PM2.5	OR	Age, sex, ethnicity, education, household income, smoking, diabetes, hypertension, province
Wu et al. (2022)a (21)	United Kingdom	Prospective cohort study; UKB recruitment 2006–2010; follow-up through 30 Nov 2020	UK Biobank participants free of age-related cataract at baseline; exclusions also included congenital lens malformations, vision loss, eye loss, prior eye surgery, and missing exposure/covariate data	291,627 (12,826)	Mean 55.83 ± 8.1 years	Mean 11.3 ± 1.8 years	Incident hospital inpatient diagnosis of age-related cataract after enrolment: ICD-10 H25. Nuclear cataract: H25.1. Non-nuclear cataract: H25.0, H25.2, H25.8, H25.9. Follow-up ended at first cataract event, death, loss to follow-up, or 30 Nov 2020.	Annual mean residential PM2.5 concentration for 2010 estimated with ESCAPE land-use regression using GIS-derived traffic and land-use variables; participant baseline residential address was matched to the exposure surface. NO2 from ESCAPE LUR was included as a covariate.	PM2.5	HR	Age, sex, ethnicity, socioeconomic and lifestyle factors, BMI, ocular/systemic comorbidities, cataract polygenic risk score, NO₂, and physical activity.
Li et al. (2023)a (7)	China	Longitudinal population-based cohort analysis of two national cohorts; CFPS baseline survey with follow-ups in 2012, 2014, 2016, 2018; CLHLS 1998–2018	China Family Panel Studies (CFPS) + Chinese Longitudinal Healthy Longevity Survey (CLHLS); Adults >50 years, cataract-free at baseline, with ≥1 follow-up; main analysis additionally required ≥3 years follow-up and complete key information	22,298 (1,897)	Mean not reported; 36.3% age 50–65 and 63.7% > 65 years	≥3 years required for main analysis; follow-up through 2018	Incident age-related cataract based on self-report of a physician diagnosis at follow-up: “Have you been diagnosed with cataracts by your doctor?” Disease status was reassessed at each follow-up.	Annual ambient PM2.5 assigned by baseline city address using a spatiotemporal land-use regression model (population density, road length, land-use variables and ambient visibility); annual predictions were used to construct long-term exposure windows.	PM2.5	HR	Age, sex, BMI, annual household income, education, smoking, drinking, marital status, ethnicity
Echevarría-Lucas et al. (2024) (35)	Spain	Ecological longitudinal/spatiotemporal observational study; Cataracts 2011–2021; pollution 2010–2020	Andalusian Health Service (Malaga–Axarquía) + INE + REDIAM; Residents of 23 municipalities; analyses for ages 15–59 and ≥60 years	134,223 (9,487)	Not reported	11-year ecological series; temporal analyses use 1-year lag	Andalusian Health Service surgical records; operable cataract (visual acuity <0.4) followed by cataract surgery; standardized incidence calculated.	REDIAM county/municipality-level annual emissions; ecological exposure assignment. Pollution series 2010–2020 linked to cataract outcomes 2011–2021.	CH4, CO, CO2, N2O, PM10, PM2.5, Total pollutants	Pearson r	No covariate adjustment in bivariate pollution–cataract correlations; study additionally examined climate, occupational and socioeconomic variables.
Hegelund et al. (2024)a (8)	Denmark	Prospective nationwide phenome-wide association cohort study; 1 Jan 2000–31 Dec 2017	Nationwide Danish population/ELAPSE-linked register cohort; All Danish residents aged ≥30 years on 1 Jan 2000 who had lived in Denmark ≥1 year	3,050,532 c (364,591)	Median 51.4 years (range 30.0–110.7)	Up to 18 years; H25 average follow-up 14.7 years	First registered diagnosis from the Danish National Patient Register and/or underlying cause of death; ICD-10 three-character outcomes. Cataract phenotypes extracted here: H25 senile cataract and H26 other cataract.	European-wide hybrid land-use regression at 100 × 100 m resolution using geocoded baseline residence; 2010 PM2.5 and NO2 surfaces were extrapolated back in time to represent long-term exposure at baseline.	NO2, PM2.5	HR	Age as underlying time axis; country of origin, cohabitation status, education, occupational status, household-size-equivalised disposable income; models stratified by sex and residential municipality.
Gayraud et al. (2025)a (22)	France	Prospective population-based cohort; Baseline 1999–2000; follow-up through 2017	3C Bordeaux/Alienor (3City-Alienor); Bordeaux residents aged ≥65 years at 3C recruitment; no cataract surgery at baseline	829 (507)	72.57 ± 4.19 years	Median 14.1 years; range 6.5–17.9 years	First cataract surgery during follow-up; self-reported year of surgery and surgery status checked by slit-lamp at repeated eye examinations.	100 × 100 m ELAPSE land-use regression at geocoded residential address; 2010 models temporally extrapolated to 1990–2016; 10-year pre-baseline average assigned.	BC, NO2, PM2.5	HR	Age, sex, deprivation index, diabetes, asthma, hypertension, lifetime ambient UVR exposure, BMI, smoking status.
Li et al. (2025) (9)	United Kingdom	Prospective population-based cohort study; Recruitment 2006–2010; follow-up to 1 Sep 2023	UK Biobank adults recruited from 22 centers in England, Scotland and Wales; participants with cataract, glaucoma or AMD at baseline and those lacking air-pollution exposure were excluded	441,567 (55,104)	Mean 56.32 ± 8.09 years	Median 14.41 years (IQR 13.64–15.07)	Incident cataract identified during follow-up through linked self-report/clinical diagnosis, primary care, inpatient hospital and death records; ICD-10 H25 (senile cataract), H26 (other cataract) and H28 (cataract/lens disorders in diseases classified elsewhere).	2010 annual mean residential air-pollution estimates from ESCAPE land-use regression models using GIS predictors (traffic intensity, population, topography, land use), assigned to home address as proxies of long-term exposure. NO was derived as NOx minus NO2.	Air pollution score, NO, NO2, PM10, PM2.5, PM ₂.₅–₁₀	HR	Age, sex, ethnicity, assessment center, Townsend Deprivation Index, education, BMI, smoking status, alcohol intake frequency, hypertension, diabetes mellitus, hyperlipidemia
Miao et al. (2025) (36)	China	Aggregate hospital time-series/ecological modeling study using Fuzzy Cognitive Maps (preprint); 1 Jan 2019–22 Jul 2024	The Central Hospital of Wuhan cataract surgery records; Patients undergoing phacoemulsification with intraocular lens implantation at The Central Hospital of Wuhan	14,086 (14,086)	Mean 70.25 ± 9.4 years	No individual longitudinal follow-up; daily hospital surgery-volume time series	Daily/aggregate volume of cataract surgeries among hospital patients undergoing phacoemulsification with intraocular lens implantation; the paper frames the outcome as senile cataract surgery volume/timing rather than incident cataract risk in individuals.	City-level Wuhan weather and air-quality data from rp5.ru and aqistudy.cn over the corresponding period. Daily environmental values were derived from >10 measurements/day when available and min-max normalized before FCM modeling.	CO, NO2, O3, PM10, PM2.5, SO2	FCM mean simple-path weight	FCM jointly modeled multiple environmental variables (air pollutants plus temperature, pressure, humidity, wind, visibility, dew point and precipitation); no individual-level clinical or sociodemographic confounder adjustment.
Wang et al. (2025) (37)	United Kingdom	Prospective cohort study; UKB recruitment 2006–2010; analysis baseline set to 1 Jan 2010; median follow-up 12.4 years	UK Biobank — participants with baseline refractometry; UK Biobank adults with refractometry at baseline; participants lost to follow-up, with pre-existing cataract/glaucoma/diabetic retinopathy/retinal detachment/macular degeneration, or missing air-pollution exposure were excluded	114,930 (13,939)	Mean 56.9 ± 7.98 years	Median 12.4 years (reported spread 1.93 years)	Incident cataract identified from linked hospital admission/diagnosis records (England, Wales, Scotland) using ICD-9/ICD-10 codes; exact cataract codes are listed in Supplementary Table 1, which was not included in the supplied main PDF.	Annual 2010 residential concentrations estimated by ESCAPE land-use regression using GIS predictors including traffic intensity, land use and topography. PM2.5/PM10 values were unavailable for addresses >400 km from Greater London and those participants were excluded.	NO2, NOx, PM10, PM2.5	HR	Age, sex, ethnicity, education, BMI, smoking, alcohol intake, hypertension, and diabetes; TDI additionally included in threshold models.
Yuan et al. (2025) (25)	United Kingdom	Prospective population-based cohort with multi-state transition analysis; UKB recruitment 2006–2010; follow-up through 30 Sep 2023	UK Biobank adults free of cataract and dementia at baseline; exclusions for baseline cataract/dementia, missing air-pollution information, missing covariates, or cataract and dementia diagnosed on the same date	409,608 (51,786)	Mean 56.4 ± 8.1 years	Median 14.5 years (IQR 13.8–15.1)	Incident cataract ascertained using UK Biobank first-occurrence fields for ICD-10 H25, H26 and H28, linking self-reported medical conditions, hospital inpatient data and death-register records. Primary cataract transition was baseline to first incident cataract.	Annual 2010 residential concentrations estimated with ESCAPE land-use regression on 100 × 100 m grids using GIS predictors (population density, traffic intensity and land use), assigned to participants’ geocoded residential coordinates. 2010 annual averages were used as proxies for long-term exposure.	Air pollution score, NO2, NOx, PM10, PM2.5, PM2.5–10	HR	Age, sex, ethnicity, Townsend deprivation index, BMI, smoking, drinking, education, physical activity, diet, hypertension, diabetes and coronary heart disease.
Zhou et al. (2025) (27)	China	Longitudinal population-based cohort analysis (retrospective analysis of CLHLS cohort data); CLHLS surveys 1998–2018	Chinese Longitudinal Healthy Longevity Survey (CLHLS); CLHLS participants across 23 Chinese provincial-level regions with repeated follow-up; final analysis required at least 3 follow-up visits and complete key covariate data	11,449 (1,714)	Mean 81.07 ± 11.76 years; 94.31% aged ≥65 years	Repeated CLHLS follow-up from enrollment to cataract self-report, death, withdrawal, or end of follow-up through 2018	Age-related cataract based on repeated self-report of a doctor diagnosis. At baseline and follow-up surveys, participants were asked whether they had received a doctor diagnosis of cataract; follow-up responses were used to track onset.	Annual maximum daily 8-hour mean ozone (MDA8 O3) derived from GBD 2019 using TOAR and CNEMC data, chemical-transport modeling with Bayesian maximum entropy, and NASA G5NR-Chem downscaling. Because individual addresses were unavailable, participants were assigned provincial-average MDA8 O3 as a surrogate exposure.	O3 (MDA8)	HR	age, sex, BMI, annual household income, education, smoking status, drinking status, marital status, ethnicity, and type 2 diabetes.
Gayraud et al. (2026)a (10)	France	Pooled analysis of two prospective cohorts; Gazel 2007–2017; Constances 2012–2021	Constances + Gazel (pooled within report); Two nationwide French prospective cohorts; participants age >53 years; baseline cataract surgery excluded	36,140 (5,543)	60.16 ± 4.59 years	10 years	Incident cataract surgery from French SNDS procedure records; first surgery date used (phacoemulsification procedure codes).	ELAPSE 100 × 100 m land-use regression at geocoded residential histories; 2010 surfaces annually rescaled; individual 10-year pre-baseline average exposure.	BC, NO2, PM2.5	HR	Age, sex, education level, and study cohort (Constances vs. Gazel)

BC, black carbon; CLHLS, Chinese Longitudinal Healthy Longevity Survey; FCM, fuzzy cognitive map; HR, hazard ratio; LUR, land-use regression; MDA8, maximum daily 8-hour mean; NO, nitric oxide; NO₂, nitrogen dioxide; NOx, nitrogen oxides; O₃, ozone; OR, odds ratio; PM₂.₅, particulate matter ≤2.5 μm; PM₂.₅–₁₀, coarse particulate matter 2.5–10 μm; PM₁₀, particulate matter ≤10 μm; SO₂, sulfur dioxide.

^aStudies contributing to at least one quantitative meta-analysis (n = 7) are marked with an alphabet (^a).

^b28,550 participants had non-missing cataract status; regression N varied according to covariate completeness.

^cMaximum cohort size varied by phenotype; N shown corresponds to the H25 senile-cataract analysis.