‘Good’ cholesterol can be linked to increased glaucoma risk in more than 55s

“Good” (HDL) cholesterol, usually considered favorable for health, can be linked to an increased risk of serious eye condition, glaucoma – at least under the more than 55s – suggest the results of a large observational study, published online in the British Journal of Ophthalmology.

Paradoxically, “bad” (LDL) cholesterol, usually considered harmful to health, can be associated with a lower risk of glaucoma, a condition that damages the optic nerve, which may lead to irreversible face loss or total blindness.

The findings -challenging got wisdom about what can help and hinders the health of the eye, and suggests that a reconsideration may be needed of how patients with high blood fats are treated and the risk of glaucoma is treated, the researchers say.

Glaucoma is expected to meet around 112 million people by 2040. Risk factors include age, ethnicity, the structure of pressure in the eye (IOP) and family history, explaining the researchers.

Abnormally high levels of circulating fats (lipids) in the bloodstream are linked to eye conditions, such as macular degeneration and diabetic retinopathy. Recently published research has also implicated a link with glaucoma, but the findings have been inconsistent and it is not clear which type of lipid is the most influential, she adds.

To strengthen the basis of evidence, the researchers used 400,229 participants from 40 to 69 in the UK Biobank Study. They had all completed a questionnaire, interviewed and had undergone a standard panel of blood tests, including those to measure blood fats.

Their health was followed on average 14 years, during which time 6,868 (almost 2%) of them developed glaucoma.

Compared to participants who did not develop glaucoma, those who did, were the tendency to be older and of non-white ethnicity. They had higher HDL, but lower LDL, cholesterol and a higher waist hip ratio (indicative of central obesity).

They were also more likely to be ex-smokers and to take 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 good HDL cholesterol were associated with an increased risk of glaucoma, while higher levels of poor 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 with the lowest level, with any (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 chance of developing glaucoma than with the lowest levels.

And any (standard deviation) increase in LDL cholesterol, total cholesterol and triglycerides reduced the risks by 4%, 3%and 4%respectively.

But these observed associations only remained with those who are older than 55, without seeing a significant association in those aged 40-55; The findings were also influenced by sex and type of glaucoma.

The researchers have drawn up a polygene risk score – a number that offers a personalized measure of genetic sensitivity to diseases by combining genetic risk information from the entire genome.

This showed that every extra genetic risk was associated with 5% higher opportunities on the development of glaucoma. But there were no significant individual associations between LDL cholesterol, total cholesterol or triglycerides and glaucoma.

This is an observational study and as such, no strong conclusions can be drawn about cause and effect. And the researchers recognize various restrictions on their findings, including that blood samples were not taken after fasting and only at a single time.

The findings may also not apply to other ethnic groups, because the British biobank participants are predominantly of European descent.

But they suggest: “These findings are challenging existing paradigms over ‘good’ and ‘bad’ cholesterol in relation to eye health. This can lead to a re -evaluation of strategies for lipid management in patients who are at risk of glaucoma.”

And they conclude: “HDL cholesterol has been considered the ‘good cholesterol’ for seven decades. [it] are not consistently associated with a favorable prognostic outcome. Further studies are needed to investigate the mechanisms behind these associations. “