According to a new study published in the “British Journal of Ophthalmology”, a cataract increases the risk of death by stroke or heart attack by more than a third.
- People who have had cataract surgery have a 13% higher risk of death from all causes. This risk rises to 36% in the event of death from vascular causes.
- Several avenues explaining this increased risk of death are being studied, in particular oxidative stress, depression and degeneration of the lenses.
A frequent pathology, affecting one person in five from the age of 65 and more than two out of three at the age of 85, cataract is a partial or total opacification of the lens, which threatens long-term sight. This slow and inevitable process, linked to age but which can also be of congenital origin or linked to an ocular trauma, a progressive loss of sight, associated with glare in bright light.
Currently, cataract surgery is the only effective treatment for cataracts and is therefore the most commonly performed ophthalmic procedure.
Several studies have already investigated the association between cataract surgery and mortality from any cause, but have produced conflicting results. In this new study, published online in the British Journal of Ophthalmologythe authors therefore set out to investigate the association between cataract surgery and mortality by examining deaths from specific causes.
A 36% higher risk of death from vascular causes
To do this, they studied data from 14,918 people aged 40 or older who participated in the 1999-2008 cycles of the National Health and Nutrition Examination Survey in the United States. Of these, 2,009 underwent cataract surgery.
Deaths were tracked over a median follow-up period of 10.8 years during which 3,966 (19.1%) of participants died. Deaths from all causes were more likely among people who reported having had cataract surgery, as were deaths from some specific causes, including vascular disease, cancer, accidents, Alzheimer’s disease, respiratory diseases and kidney diseases.
After controlling for a range of socioeconomic and health factors, only the association between self-reported cataract surgery and vascular disease mortality remained significant. Thus, the risk of death from all causes was 13% higher in people who had undergone cataract surgery, and the risk of death from vascular causes was 36% higher.
Several triggers under study
While this is an observational study, which therefore cannot establish a cause, the researchers suggest, however, that oxidative stress, crystalline lenses or depression could be the common factor explaining why cataracts increase the risk of vascular death.
The authors suggest that oxidative stress, lens or depression may be the common factor linking cataract and increased risk of vascular death. Studies have shown that DNA damage induced by oxidative stress contributes to the formation of cataracts and promotes atherogenesis, the process of forming deposits of lipoproteins on the walls of arteries.
The lens degeneration that occurs in cataracts may also represent a more prevalent disorder that contributes to higher vascular mortality. Finally, it has been shown that patients with cataracts are more likely to develop depression than others, and that people with depression have a higher risk of developing cardiovascular disease.
“Further studies are needed to confirm these associations and to elucidate the mechanisms underlying these associations”conclude the authors.
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