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EW GLAUCOMA 98 October 2014 tion of extracellular fluid in dependent positions, causing choroidal vascular congestion." "Given that obese people have absolute and relative expansion of extracellular fluid compared to normal weight controls," she continued, "we hypothesize greater changes in postural IOP in obese patients compared to controls." To test this hypothesis, she and colleagues recruited 25 obese patients (BMI >30) scheduled for weight loss surgery, and 25 age- and gender-matched controls with BMI <30. All 50 subjects underwent IOP assessments using the Tono-Pen (Reichert Technologies, Depew, N.Y.) in 7 positions in random order: head straight, flexed, and extended in the sitting position; flat, right and left lateral decubitus; and head and torso elevated 30 degrees in the supine position. As expected, IOP was higher in the supine positions than in the sitting positions. However, there was no difference in the amount by which IOP increased with body position between the obese and control groups. Interestingly, the mean IOP in every single body position was 2 to 3 mmHg higher in the obese patients than in the controls. Clinical implications For now, these studies raise more questions than they answer, and recommending weight loss for glaucoma patients would be premature and not supported by the existing body of evidence. However, it is intriguing that IOP is higher in obese people. "This suggests that increased extracellular fluid and choroidal vascular congestion may not be the only mechanism for elevated IOP in obesity," said Dr. Lam. She and her colleagues are now planning to assess IOP changes in obese patients before and after weight loss surgery to see whether dramatic weight loss has a beneficial effect on IO . EW Editors' note: Drs. Lam and Sannohe have no financial interests related to their comments. Contact information Lam: cindy.ty.lam@gmail.com Sannohe: schikako@estate.ocn.ne.jp by Tony Realini, MD, MPH Can glaucoma be managed with lifestyle modification ponents of metabolic syndrome, including obesity (measured by body mass index [BMI]) and diabetes. Among POAG patients com- pared to the age-matched controls, they found statistically significant associations between glaucoma risk and gender (females being at higher risk), the presence of diabetes, and lower BMI. In the NTG group, younger age, systemic hypertension, and diabetes were risk factors, but BMI was not. This was not a population-based study, the investigators pointed out, but rather a hospital- and clinic-based study. Nevertheless, "other than diabetes, the systemic risk factors for NTG and POAG were different from one another," Dr. Sannohe said. Obesity and postural IOP changes The jury may still be out on wheth- er obesity can cause glaucoma. For people who already have glaucoma, can obesity make it worse? "Studies have shown that IOP increases in the supine position by as much as 6 mmHg," said Dr. Lam, "and that this difference is correlated with glaucomatous progression. The mechanism is thought to be related to redistribu- Metabolic syndrome Humans are getting heavier. "In the U.S., 1 in 3 adults is obese," said Cindy Lam, MD, University of Toronto. "In Canada, 1 in 4 adults are obese." Globally, the worldwide prevalence of obesity is expected to triple over the next 15 years. The epidemic of obesity has resulted in a higher than ever prev- alence of diabetes and metabolic syndrome, a combination of obesity, systemic hypertension, and dyslip- idemia that greatly increases the risk of diabetes, heart disease, and stroke. "It has yet to be fully elucidated whether or not an association exists between various components of metabolic syndrome and open-angle glaucoma," said Chikako Sannohe, MD, Japan. Various epidemiological studies have examined this issue with mixed results. Some find no relationship between obesity and glaucoma; others find obesity to be a risk factor; and still others have reported obesity as a protective fac- tor reducing the risk of glaucoma. To address this issue, Dr. Sannohe and colleagues conducted a study of 1,141 subjects including both POAG and NTG patients as well as age-matched normal con- trols, to evaluate the relationship between glaucoma and the com- L owering IOP remains the only established treat- ment for glaucoma, and all approved therapies for glaucoma—medical, laser, and surgical—work by lowering IOP. Also, IOP reduction is effective in reducing disease progression across the spectrum of IOP, from normal tension glaucoma (NTG) to primary open-angle glaucoma (POAG). Accordingly, we tend to be IOP-centric in our interactions with our patients. Despite this, our glaucoma patients frequently ask us this question: "Is there anything else I can be doing, besides taking my drops every day, to lower my risk of losing vision?" Unlike with age-related macu- lar degeneration (AMD), we cannot legitimately promote nutraceutical supplementation for glaucoma, as there has been no evidence to date of tangible effects from vitamin or mineral supplementation. Likewise, while smoking cessation may be of value in preventing progression of both AMD and cataract, benefit in glaucoma progression has not been observed. Body weight, however, may be a different story.