Cataract, Cataract Surgery, and Risk of Incident Dementia: A Prospective Cohort Study of 300,823 Participants.

Background: Visual impairment and interventions to preserve vision may impact dementia risk. Thus, we aimed to explore the associations of cataract and cataract surgery with the risk of dementia.

Methods: Prospective data from 300,823 individuals in the UK Biobank were used. We used multivariate Cox proportional hazards regression models to estimate hazard ratios (HRs) and 95% confidence intervals for associations, with healthy control subjects as a reference. The same method was used to explore the effects of surgery on dementia outcomes of patients with cataract. One-way analysis of variance was performed to examine the associations between cataract and brain morphometric measures.

Results: After a mean follow-up of 8.4 years, 3226 individuals were diagnosed with dementia. The nonsurgical cataract group had increased risk of all-cause dementia (HR, 1.214; 95% CI, 1.012-1.456; p = .037) and Alzheimer's disease (HR, 1.479; 95% CI, 1.105-1.981; p = .009). However, there was no difference in dementia risk between the cataract surgery group and the healthy control group. Cataract surgery was associated with decreased risk of all-cause dementia (HR, 0.632; 95% CI, 0.421-0.947; p = .026) and Alzheimer's disease (HR, 0.399; 95% CI, 0.196-0.812; p = .011) compared with the nonsurgical group. Additionally, cataract was negatively associated with cortical volumes, aging-related subcortical volumes, and fractional anisotropy of white matter fibers.

Conclusions: Cataract patients who did not receive surgical treatment had an increased risk of dementia. However, cataract surgery could reverse the risk of dementia. Our findings on brain structures and pathways in patients with cataract also provided evidence for the mechanism. Reversible visual impairment, such as cataract, is a promising modifiable risk factor for dementia.