Cataract surgery may prevent cognitive decline, dementia in older adults

A recent study has observed a possible link between cataract surgery and a reduced risk of cognitive impairment and dementia, indicating cataract-related vision impairment as a potentially modifiable risk factor for cognitive decline. 

Investigators searched the databases of PubMed, Embase, and Cochrane Library from inception through 11 October 2022 for studies reporting the effect of cataract surgery on cognitive impairment and dementia. They pooled adjusted hazard ratios (HRs) for dichotomous outcomes and ratio of means (RoM) for continuous outcomes using a random-effects model. 

Sensitivity and subgroup analyses were also conducted to examine heterogeneity. Finally, the investigators assessed the quality of evidence using the Newcastle–Ottawa scale, Cochrane risk-of-bias tool for randomized trials, and Grading of Recommendations, Assessment, Development and Evaluations (GRADE) guidelines. 

Twenty-four articles consisting of 558,276 participants met the eligibility criteria. Of these, 19 were analysed qualitatively. Study bias ranged from low to moderate, while GRADE was very low to low. 

Cataract surgery contributed to a 25-percent lower risk of long-term cognitive decline relative to those with uncorrected cataracts (HR, 0.75, 95 percent confidence interval [CI], 0.72–0.78). This benefit persisted across various cognitive outcomes and remained robust to sensitivity analyses. 

Participants who underwent cataract surgery were comparable to healthy controls without cataracts as regards their risk of long-term cognitive decline (HR, 0.84, 95 percent CI, 0.66–1.06).  

Cataract surgery also contributed to a 4-percent improvement in short-term cognitive test scores among participants with normal cognition (RoM, 0.96, 95 percent CI, 0.94–0.99). However, no significant association was seen among those with pre-existing cognitive impairment. 

“Physicians should be aware of the cognitive sequelae of cataracts and the possible benefits of surgery,” the authors said. “The cognitive benefits of cataract surgery should be investigated further in randomized trials.”