In yet another example of too much of a good thing being bad for you, researchers in China have discovered that ‘good’ cholesterol may mean a heightened risk of glaucoma.
And the large observational study, published in the British Journal of Ophthalmology, says ‘bad’ (LDL) cholesterol, usually regarded as harmful to health, may be associated with a lower risk of the eye disease.
A release associated with the research said the findings “challenge received wisdom about what may help and hinder eye health, and suggest that a rethink may be needed of how patients with high blood fats and who are at risk of glaucoma, are treated”.
Glaucoma is projected to affect around 112 million people by 2040. Risk factors include age, ethnicity, the build-up of pressure within the eye (IOP), and family history, explain the researchers, from the Zhongshan Ophthalmic Center at Sun Yat-sen University in Guangdon, China.
Abnormally high levels of circulating fats (lipids) in the bloodstream have been linked to eye conditions, such as macular degeneration and diabetic retinopathy. Recently published research has also implied a link with glaucoma, but the findings have been inconsistent, and it’s not clear which type of lipid might be most influential, they add.
The researchers drew on 400,229 participants aged 40 to 69 in the UK Biobank Study.
Their health was tracked for an average of 14 years, during which time 6868 (nearly 2%) of them developed glaucoma.
Compared with participants who didn’t develop glaucoma, those who did, tended to be older, and of non-white ethnicity. They had higher HDL, the ‘good’ cholesterol, but lower LDL and a higher waist-to-hip ratio (indicative of central obesity).
They were also more likely to be ex-smokers, and to be taking statins, and they had a higher prevalence of diabetes, high blood pressure, and cardiovascular disease.
But analysis of the blood test results showed that higher levels of HDL cholesterol were associated with a heightened risk of glaucoma while higher levels of LDL cholesterol, total cholesterol, and triglycerides were associated with a lower risk.
Those with the highest level of HDL cholesterol in their bloodstream were 10% more likely to develop glaucoma than those with the lowest level, with every (standard deviation) increase associated with a 5% higher risk.
Similarly, participants with the highest levels of LDL cholesterol and triglycerides were 8% and 14%, respectively, less likely to develop glaucoma than those with the lowest levels.
And each (standard deviation) increase in LDL cholesterol, total cholesterol, and triglycerides lowered the risks by 4%, 3%, and 4%, respectively.
But these observed associations only persisted among those older than 55, with no significant association seen in those aged 40–55; the findings were also influenced by sex and type of glaucoma.
The researchers said: “These findings challenge existing paradigms about ‘good’ and ‘bad’ cholesterol in relation to eye health. This could prompt a re-evaluation of lipid management strategies in patients at risk for glaucoma.
“HDL cholesterol has been regarded as the ‘good cholesterol’ for seven decades. However, this study demonstrates that high levels of [it] are not consistently associated with a favourable prognostic outcome.
“Further studies are needed to investigate the mechanisms behind these associations.”
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