By: ROCIO C. PASION, O.D.
The New York Times (January 24, 2022, cataract surgery may reduce dementia risk).
“Older adults who had cataract removal to restore their vision had a lower risk of Alzheimer’s disease and other forms of dementia.”
Cataract surgery is considered a modern-day miracle. At present, approximately 4 million cataract surgeries are performed every year in the United States and 60,000 cataract procedures are performed every day globally. Due to increases in the population’s life expectancy, it is expected that the number of cataract surgeries will grow 3-4% per year over the next 30 years with a projection of 100 million cataract procedures being performed annually by the year 2050. (Ocular surgery News 2/10/2021).
50 million people worldwide are affected by dementia. Several studies suggest sensory loss may be a potentially modifiable risk factor for dementia later in life. “The prevalence of hearing (1 out of 3) and vision impairment (1 out of 5) in adults ages 70 or older in the U.S. is high.” Sensory impairment and dementia are both strongly associated with aging, interventions to improve sensory function to reduce dementia risks are being studied.
Previous research show that vision loss-as well as hearing loss-are important risk factors for cognitive decline. With vision loss, the visual cortex undergoes physiological changes to include brain shrinkage, which is also a risk factor for dementia.
A new study found that the overall risk for dementia was nearly 30% lower in those who had cataract surgery.
According to the National Institute in Aging (NIA) study, researchers analyzed data from a subset of participants from the Adult Changes in Thought (ACT) Study, an ongoing, population-based cohort of randomly selected, members of Kaiser Permanente Washington. Participants were 65 years or older, dementia-free at the start of the study, and were diagnosed with cataracts before the onset of dementia. All of the subjects were followed as part of a decades-long study.
One of the major strengths of the study is that the observational cohort allowed for years of follow up starting before participants developed dementia. The research suggests that quality of life improvement for those who have cataract surgery is considerable given its lasting effect beyond 10 years.
The study, in JAMA Internal Medicine, “adjusted for age at first diagnosis of cataracts as well as various risk factors for dementia, including few years of education, smoking, a high body mass index and hypertension.”
If validated in future studies, cataract surgery may be a clinically relevant mean of protecting cognition.
(Lee CS, et al. Association between cataract extraction and development of dementia. JAMA Internal Medicine, 2022; 182 (2): 134-141. doi;10.1001/jamainternmed.2021.6990)