When managing glaucoma, high intraocular (internal eye) pressure, or IOP, is the most important—as well as the sole modifiable—risk factor. Identifying and addressing contributors to elevated IOP has been the focus of many glaucoma studies. Scientists have explored the question of whether or not obesity is linked to increased IOP and, while associations have been drawn, actual research results have been mixed. Now, findings from a large Korean study suggest that metabolic health may be a more significant factor in managing IOP.*

Obesity, metabolic health, and IOP

Obesity is defined as a body mass index of 30 or higher. In the Journal of Clinical Medicine, researchers in Seoul, Korea explain that many studies have shown obesity to be an independent risk factor for, and positively associated with, elevated IOP; yet, other studies have shown only a weak association or no association. Still, they say, a growing body of evidence supports interactions between obesity and metabolic health subgroups as culprits,

• One subgroup is metabolically healthy but obese (MHO), showing good insulin sensitivity, healthy blood fats (triglycerides, cholesterol), and no high blood pressure.
• Another subgroup is metabolically unhealthy but shows normal weight (MUNW), marked by excessive deep body fat and tied to a higher risk of death, heart disease, metabolic diseases, cancer, and greater body-wide inflammation.

The researchers say they’ve previously shown a link between obesity, metabolic health, and IOP, and have tied the interaction of these factors to glaucoma. In the current study, they wanted to determine how this interaction of factors might affect IOP.

What the researchers did

The researchers compared the IOP of 20,385 participants, aged 19-35, after dividing them into four groups based on their level of obesity starting at 25 (25-29.9 indicates “overweight”) and metabolic health status. These groups were identified as:

• Metabolically unhealthy and obese (MUO)
• Metabolically unhealthy but with normal weight (MUNW)
• Metabolically healthy but obese (MHO)
• Metabolically healthy and with normal weight (MHNW)

Unhealthy metabolic status was defined by several factors, including:

• Abdominal obesity,
• Unhealthy blood fat levels,
• Low HDL (“good”) cholesterol,
• High blood pressure, and/or
• Elevated fasting blood glucose levels.

What they found

With normal IOP ranging from 12-21 mm Hg (millimeters of mercury), the researchers found that:

• The MUO group had the highest average IOP, at 14.38.
• The MUNW group had the second-highest average IOP (14.22).

The metabolically healthy groups had the lowest average IOPs, with the MHO group at 13.5 and the MHNW group at 13.06. 

What it means

The findings showed that people who were metabolically healthy at all BMIs had lower eye pressure than metabolically unhealthy people, and IOP increased as metabolic disease factors increased, regardless of weight status. 

“While obesity, metabolic health status, and each component of metabolic disease were associated with higher IOP,” the authors wrote, “those in the metabolically unhealthy normal-weight group showed higher IOPs than those who were metabolically healthy but obese, which indicates that the metabolic status has a greater impact than obesity on IOP.”

These results have public health implications, the authors concluded, and illustrate that improving metabolic health should play a major role in managing eye pressure.

*Charters, L. (2023, March 14). Study examines links between metabolic health, obesity and IOP. Ophthalmology Times. https://www.ophthalmologytimes.com/view/study-examines-links-between-metabolic-health-obesity-and-iop