Three studies reported on the outcome of cataracts.
4,21,24 First, results from Choi et al.
21 found that there was no statistically significant association between PM
10, NO
2, or SO
2 exposure and any cataract in single- or multipollutant models. However, the results for NO
2 differed by cataract subtype. NO
2 (per 0.003-ppm increase) showed a protective association with anterior subcapsular cataracts (OR = 0.69; 95% CI, 0.52–0.93) in the multipollutant model only and a protective association with nuclear cataracts in the single-pollutant (OR = 0.89; 95% CI, 0.83–0.94) and multipollutant models (OR = 0.88; 95% CI, 0.79–0.97). Choi et al.
21 also found a statistically significant protective relationship between O
3 exposure (per 0.003-ppm increase) and any cataract that was consistent across single-pollutant (OR = 0.87; 95% CI, 0.78–0.96) and multipollutant (OR = 0.80; 95% CI, 0.69–0.93) models. When assessing by cataract subtype, there was a statistically significant relationship between O
3 exposure with nuclear cataract in both single-pollutant (OR = 0.89; 95% CI, 0.83–0.94) and multipollutant (OR = 0.73; 95% CI, 0.61–0.86) models but not for anterior subcapsular, posterior subcapsular, or cortical cataracts.
21 Second, in contrast to Choi et al.,
21 Shin et al.
4 found that higher exposure to NO
2 (HR = 1.08 for the highest quartile; 95% CI, 1.03–1.13) was associated with an increased risk of cataract. They also found that PM
10 was associated with an increased risk of cataract (HR = 1.07 for the highest quartile; 95% CI, 1.03–1.12). Also in contrast to Choi et al.,
21 those in the second and third quartiles of SO
2 exposure had a higher cataract incidence, with HRs of 1.07 (95% CI, 1.02–1.11) for the second quartile and 1.05 (95% CI, 1.00–1.09) for the third quartile. The fourth quartile did not have a higher incidence (HR = 1.03; 95% CI, 0.98–1.07). Shin et al.
4 found a protective association between O
3 and cataract (
P value for linear trend = 0.013). There was no increased risk of cataract reported for those with greater exposure to PM
2.5. Finally, Grant et al.
24 reported a borderline association between PM
2.5 and cataract (OR = 1.06 per IQR; 95% CI, 0.99–1.14) in a single-pollutant model. However, they did not find an increased odds of cataract among those with greater exposure levels to PM
2.5 (OR = 0.98 per IQR; 95% CI, 0.90–1.07) in the multipollutant model. Further, higher O
3 levels were reported to be inversely associated with cataract in a multipollutant model (OR = 0.92 per IQR; 95% CI, 0.85–0.99).
24 No association was found for NO
2 or SO
2 with cataract in a multipollutant model.