A recent study has raised eyebrows in the medical community by suggesting a potential link between high levels of high-density lipoprotein cholesterol (HDL-C), commonly known as "good" cholesterol, and an increased risk of developing glaucoma. Conducted with participants whose lipid levels were determined from a single non-fasting blood sample, the study found that those with elevated HDL-C levels were more likely to develop this eye condition. However, the findings have sparked debate among experts, with some cautioning against drawing firm conclusions without further investigation.
Alexander Solomon, MD, a neuro-ophthalmologist, expressed skepticism regarding the study's methodology. He emphasized the need for more rigorous research involving ophthalmologists to define glaucoma subtypes and severity accurately. Similarly, Yu-Ming Ni, MD, a cardiologist, was taken aback by the results, noting that the mechanism linking higher HDL-C to increased glaucoma risk remains unclear.
"As stated, this study poses an interesting possibility but leaves many concerns unanswered. I'd like to see a more stringent study done that actually used ophthalmologists to help define specific glaucoma subtypes and severity and followed fasting lipid levels over time as this would be a much stronger correlation." — Alexander Solomon, MD
Interestingly, the study also revealed that participants with the highest levels of low-density lipoprotein cholesterol (LDL-C) and triglycerides were less likely to develop glaucoma. Those with elevated LDL-C had an 8% reduced risk, while participants with higher triglyceride levels showed a 14% decreased likelihood of developing the disease. These findings contradict conventional expectations regarding cholesterol's impact on health.
"The definition of glaucoma here is somewhat suspect, as it must be when you're using a database rather than directly recruiting or interacting with patients," Solomon explained.
"At first glance, higher lipids should be associated with worse outcomes overall, including higher rates of glaucoma," Ni explained.
The study's results have prompted discussions about potential confounding factors that may have influenced the findings. Dr. Ni pointed out that both excessively high and low HDL-C levels are linked to increased heart disease rates. This suggests the possibility of other factors at play in the relationship between HDL-C and glaucoma.
"Given that the mechanism by which higher HDL may be associated with higher glaucoma risk is unknown, I suspect this finding may be confounded by other factors. It is also known that both too high and too low HDL-C are associated with higher rates of heart disease. In other words, there is such a thing as too much good cholesterol." — Yu-Ming Ni, MD
Despite the intriguing results, experts urge caution in interpreting the study's implications. Dr. Ni maintains his stance on healthy HDL-C levels for cardiovascular health and advises against altering medical advice based solely on this study.
"You can study a therapy that lowers HDL-C and assess if glaucoma rates are lower. I suspect this type of study will never be done because of the fear of higher rates of heart disease. But it would be wrong to assume that higher HDL would increase your risk of glaucoma without knowing the mechanism or understanding confounding risk factors. Therefore, I'm not making a big deal out of this study, and I will continue to counsel patients that the ideal HDL-C is about 50-60 for men and 60-70 for women," he said.
Glaucoma is recognized as the second leading cause of blindness, following cataracts. Unlike cataracts, however, glaucoma results in irreversible damage to vision, often affecting peripheral sight first. Patients may remain asymptomatic for years before noticing any visual impairment.
"Glaucoma is the second most common cause of blindness, and unlike cataracts, which are the most common, it is irreversible," Solomon explained.
"Knowing health concerns that could increase someone's risk may help direct us to screening patients sooner or more frequently to catch them before the disease really affects their vision. Similarly better understanding risk factors for glaucoma may help us elucidate some of the more mysterious mechanisms of glaucoma, which can occur and progress seemingly independent of elevated intraocular pressure, which is its most classically associated risk factor." — Alexander Solomon, MD
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