The association between cataract and incidence of cognitive impairment in older adults: A systematic review and meta-analysis

Cataract has been shown to be associated with an increased risk of cognitive impairment. However, the results of previous studies have been inconsistent. This systematic review and meta-analysis aimed to investigate the association between cataract and the incidence of cognitive impairment in older adults. A comprehensive search of electronic databases from inception to January 2023 was performed to identify relevant studies. Data were extracted from eligible studies and a meta-analysis was performed to calculate the pooled hazard ratio (HR) and 95% confidence interval (CI). We included 13 studies with 25 study arms involving a total of 798,694 participants. Compared with participants without cataract, those with cataract had a higher risk of developing all-cause dementia (pooled HR: 1.22; 95 % CI: 1.08–1.38; I2 =86 %; 9 studies), Alzheimer's disease dementia (pooled HR: 1.18; 95 % CI: 1.07–1.30; I2 =0 %; 9 studies), vascular dementia (pooled HR: 1.21; 95 % CI: 1.02–1.43; I2 =77 %;3 studies) and mild cognitive impairment (pooled HR: 1.30; 95% CI: 1.13–1.50; I2 =0%;2 studies). There was no significant association between cataract and mixed dementia (pooled HR: 1.03; 95 % CI: 0.52–2.04; I2 =78 %;2 studies). We assessed the risk of bias of the included studies using the Newcastle-Ottawa Scale and found that most of them had a low or moderate risk of bias. The number of studies in each meta-analysis ranged from two to nine, with more studies available for all-cause dementia and Alzheimer's disease dementia than for vascular dementia and mixed dementia. The findings suggest that cataract may be associated with cognitive impairment in older adults. However, the causal relationship between cataract and cognition remains unclear and requires further investigation.