Large Association Study Finds Cataract Surgery Linked with Lower Risk of Dementia & Alzheimer's Disease

Article: Cataract surgery linked with lessened dementia risk
Source: University of Washington Medicine
Published: December 6, 2021
Article: Cataract Surgery Linked to Lower Risk of Developing Dementia, Even 10 Years Later
Source: ScienceAlert
Published: December 10, 2021 

Cataracts are an opacification or clouding of the eye's crystalline lens, most commonly as a result of aging and decades of filtering ultraviolet radiation. Although connections between poor vision and cognitive decline have been explored in many studies, ophthalmologists at University of Washington were interested in the effect of surgical intervention in the form of cataract extraction on dementia risk. Specifically, they looked at data from the Adult Changes in Thought (ACT) study, an ongoing longitudinal cohort study started in 1994 by Kaiser Permanente Washington and designed to study the development of dementia. Electronic medical records data was collected from 3,038 participants 65 years of age or older who had either cataract or glaucoma diagnosis before enrollment or during follow-up care. Among those included in the analysis, there were 853 cases of dementia (all cause) and 709 cases of Alzheimer's disease. Approximately half of the participants (1,382 individuals) had cataract surgery. Based on 23,554 person-years of follow-up, and after controlling for a variety of potentially confounding factors, participants who underwent cataract extraction in either eye had a 29% reduced risk of developing dementia compared to participants without surgery; moreover, the reduced risk applied for at least 10 years after surgery. Similar findings were seen in dementia specific to Alzheimer's disease. Importantly, no association was observed between glaucoma surgery and dementia risk. The authors point out that evaluation of glaucoma surgery, which, unlike cataract surgery, does not restore vision, was to address potential healthy patient bias. Although the mechanisms by which cataract extraction is associated with decreased dementia risk were not explored in this observational study, the researchers hypothesize that patients were getting higher quality sensory input after cataract extraction, highlighting neurological, circadian, and social improvements. Lead researcher of the study states, "This kind of evidence is as good as it gets in epidemiology. This is really exciting because no other medical intervention has shown such a strong association with lessening dementia risk in older individuals." Given the risk of cognitive decline in older age, interventions such as cataract surgery have major clinical relevance not only in enhancing quality of vision but also in improvement of mental health.

My rating of this study: ⭐⭐⭐⭐🌸

Lee CS, Gibbons LE, Lee AY, et al. "Association Between Cataract Extraction and Development of Dementia." JAMA Internal Medicine.  238:3391-3398. 6 December 2021. https://doi.org/10.1001/jamainternmed.2021.6990