Cataract linked to increased risk of strokes, heart attacks

Clinically significant cataract is associated with an increased risk of death from vascular causes, such as stroke and heart attack, according to research published online in the British Journal of Ophthalmology.

Researchers from The University of Melbourne, Centre for Eye Research Australia (CERA) and Guangdong Eye Institute, China, studied 14,918 people aged 40 years or older who had participated in the 1999–2008 cycles of the National Health and Nutrition Examination Survey in the United States. This included 2009 people (9.61%) who reported that they had undergone cataract surgery. They tracked deaths over a period of 10.8 years, during which 3966 (19.1%) of the participants died.

They found that people who had surgery for cataracts had a 36% higher risk of dying from vascular diseases. The risk of death from any cause was 13% higher in people who self-reported cataract surgery compared to participants who had not undergone the surgery, and the risk of death from vascular causes was 36% higher.

Stress or depression may be the common factor linking cataracts and greater risk of vascular death, suggested the authors. No significant association was observed specifically between self-reported cataract surgery and cancer, respiratory disease, renal disease, Alzheimer’s disease or accidents.

Oxidative stress, crystallins or depression may be the common factor linking cataract and greater risk of vascular death. Studies have shown that oxidative stress-induced DNA damage contributes to cataract formation and promotes atherogenesis, according to the authors.

Crystallins are major components of the lens and are also involved in regulating responses to stressors such as inflammation and ischaemia; the degeneration of crystallins which occurs in cataract may represent a more widespread disorder which contributes to the higher vascular mortality.

Patients with cataract have been shown to be more likely to develop depression than those without the condition, even after they had undergone cataract surgery, and people with depression are at higher risks of developing CVD.

This is an observational study, and as such, can’t establish cause, and the authors also highlight several potential limitations. Self-reported cataract surgery was used as a surrogate for clinically significant cataract, which meant that some cataract cases could have been missed, and it was not possible to determine the type of cataract affecting patients and whether specific types of cataracts were associated with deaths from specific causes.

Nevertheless, the authors concluded: “This study found significant associations of self-reported cataract surgery with all-cause and vascular mortalities. More studies are needed to confirm these associations and to further investigate the mechanisms behind these associations.”

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