Why eye surgery reduces your risk of dementia
Close-up of the eye: In cataracts, the natural lens becomes cloudy, up to and including loss of vision
Quelle: Getty Images
For decades, researchers have been looking for remedies against dementia. Now, a study suggests that certain eye surgery can significantly reduce the risk. There is also an explanation for this.
She is the most frequently performed surgical procedure on the eye: cataracts. In Germany alone, ophthalmologists remove around 600,000 natural, cloudy lenses every year in order to replace them with clear lenses made of plastic. Worldwide there are even more than 100 million cataract operations per year.
Such an operation against cataracts not only helps patients to have a significantly better view and a better quality of life – it also helps older people to have a significantly reduced risk of dementia in the following years. This is the result of a new study that has now been published in the journal “JAMA Internal Medicine”.
In the long-term study, the neurodegenerative disease occurred almost 30 percent less often in those patients who had undergone the eye surgery than in the others. Several mechanisms could explain the phenomenon, writes the team led by Cecilia Lee from the University of Washington in Seattle. A German expert speaks of a “very interesting study”.
Risk of dementia after surgery reduced by 29 percent
Cataracts are mostly age-related eye diseases in which the lens becomes increasingly cloudy – up to and including loss of vision, which can, however, be prevented with cataract surgery. Dementia such as Alzheimer’s syndrome mainly affects older people, although there is no therapy for it.
The basis of the study is a long-term study that was started in the mid-1990s and observed around 5500 people aged 65 and over who initially showed no evidence of dementia. Lee’s team examined the 3,000 or more participants who were diagnosed with cataracts – with an average age of 74 years.
Almost half of them (45 percent) had cataract surgery. A total of 853 dementias had been diagnosed by 2018, most of them cases of Alzheimer’s. In those who had an operation, the risk of dementia was reduced by 29 percent.
When analyzing the data, the researchers not only took into account influencing factors such as age, weight, blood pressure, smoking, diet, exercise or education. They also checked whether those people who had undergone the procedure were generally healthier or more health-conscious.
Decreasing eyesight leads to withdrawal from social life
As a further control, they analyzed the development of 728 participants who were operated on for glaucoma – that is, glaucoma. This is damage to the optic nerve, usually caused by increased intraocular pressure. In contrast to cataract surgery, the procedure does not improve eyesight, but only prevents further deterioration. The team found no connection here with the risk of dementia.
The researchers emphasize that an observational study cannot prove a causal relationship. But: “This evidence is as good as it is possible in epidemiology,” the ophthalmologist Lee is quoted in a statement from her university. No other treatment has so far shown such a strong protective effect in relation to dementia.
To explain the phenomenon, the authors consider various mechanisms to be possible: For example, declining eyesight in people could lead to a withdrawal from social and sporting activities, which in the long term would increase the risk of dementia. In addition, the transmission of neural impulses to the brain generally decreases with cataracts.
Gerd Geerling, Director of the Clinic for Ophthalmology at the University Hospital Düsseldorf, considers the connection to be plausible. “The study confirms our thinking that reduced sensory perception is associated with a risk of dementia,” says the President of the German Ophthalmological Society (DOG), who was not involved in the study.
OP only makes sense if the eyesight is impaired
In addition, cataracts reduce contrast vision, which presumably increases the tendency towards depression – another risk factor for dementia. “After the procedure, people can participate better in social life again and have more intellectual input.”
The Düsseldorf expert emphasizes, however, that the operation only makes sense if you notice a reduction in vision. According to this, up to 800,000 cataract operations are performed in Germany each year.
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