A recent systematic review and meta-analysis published in Ophthalmology suggests that cataract surgery may be associated with a lower risk of dementia and long-term cognitive impairment.
Give me some background first.
Cataracts are a leading cause of vision loss worldwide, and global cases of dementia are expected to surpass 152 million by 2050.
Previous studies have linked cataracts with cognitive decline and dementia, potentially due to the decrease in neuronal input.
Now, talk about the review.
Recent research into the link between cataract surgery and cognitive function has ranged from suggesting that cataract surgery can improve short-term cognitive function or even reverse the long-term risk of dementia.
Since these studies do not all concur, the authors of the systematic review conducted a meta-analysis of 24 studies with 558,276 participants.
What was included in the analysis?
Out of 3,849 studies with populations of adults diagnosed with cataracts who underwent cataract surgery—and where cognitive tests were performed—24 articles met the full inclusion criteria. These included:
- 16 prospective cohorts
- One retrospective cohort
- Three cross-sectional cohorts
- One randomized control trial (RCT)
- One single-arm trial
- One prospective controlled clinical trial
- One prospective case series
This resulted in a total of 558,276 participants:
- 261,588 male
- 96,610 female
- Mean age of 66.4 years
Findings?
In the final analysis, the authors found that “cataract surgery was associated with a 25% lower risk of long-term cognitive impairment and dementia compared to participants with uncorrected cataracts.”
Additionally, this risk was comparable to that of the control groups—that is, those without cataracts.
Furthermore, the authors noted, “cataract surgery among participants with normal cognition was associated with a 4% improvement in short-term cognitive test scores assessing general cognition.”
What about for patients with pre-existing cognitive impairment?
No association was found between short-term cognitive test score improvements and cataract surgery for these patients.
Limitations?
The authors noted many limitations of the review, including that many of the studies did not control for many confounding variables, and a number were non-randomized observational studies with limited tools for cognitive assessment and non-comprehensive documentation.
Take home.
Ultimately, the authors argued, this meta-analysis demonstrates the need for RCTs to investigate the cognitive benefits of cataract surgery.
In the meantime, they suggested, “vision impairment from cataracts may be a modifiable risk factor for cognitive decline” that physicians should consider as one of the many potential benefits of cataract surgery.