HEALTH NEWS

Study Title:

Thyroid and Glaucoma

Study Abstract

Aims: To evaluate the association between thyroid problems and glaucoma.

Methods: A population-based cross-sectional sample with 12,376 participants from the 2002 National Health Interview Survey (NHIS). Odds ratios (OR) and 95% confidence intervals (CI) were used to quantify the association between a self-reported diagnosis of glaucoma and a self-reported history of thyroid problems, controlling for demographic characteristics and smoking status.

Results: The overall prevalence of glaucoma was 4.6%; 11.9% reported a history of thyroid problems. The prevalence of glaucoma among those who did and did not report thyroid problems was 6.5% and 4.4%, respectively (p=0.0003). Following adjustment for differences in age, gender, race, and smoking status, the association between glaucoma and thyroid problems remained (OR 1.38, 95% CI 1.08-1.76).

Conclusions: The results of this study lend support to the hypothesis that thyroid disorders may increase the risk of glaucoma. Research should continue evaluating potential mechanisms underlying this relationship and whether the treatment of thyroid problems reduces subsequent glaucoma risk.

From press release:

People with a thyroid disorder run an increased risk of developing the eye disease glaucoma, a new study suggests.

In fact, those with glaucoma are 38 percent more likely to have had a thyroid condition at some point in their life, said the study authors, from the University of Alabama at Birmingham. Glaucoma is the leading cause of irreversible blindness worldwide.

"Studies like this are very useful in understanding what causes this disease," said lead researcher Gerald McGwin, vice chairman of the Department of Ophthalmology at the university's School of Medicine.

"If we can determine that thyroid problems are related to glaucoma, then we can make some hypotheses about what the mechanism behind that relationship might be and help us understand what might be the cause of glaucoma," McGwin said. "And that may lead to more effective treatments or preventive measures."

The findings were published online Oct. 16 in the British Journal of Ophthalmology.

For the study, McGwin's team collected data on 12,376 people who participated in the 2002 National Health Interview Survey. They were asked if they'd ever been diagnosed with a thyroid problem or glaucoma. Slightly more than 4.5 percent said they had glaucoma, and 12 percent said they had been diagnosed with a thyroid problem.

Among people who had glaucoma, 6.5 percent said they had a thyroid problem, while 4.4 percent said they'd never had a thyroid condition.

People with thyroid problems should see an ophthalmologist or make their ophthalmologist aware of their thyroid condition, McGwin advised. "Somebody who has a history of thyroid problems and has not seen an ophthalmologist may have a heightened level of concern about their eyesight," he said.

The thyroid produces hormones essential for the functioning of every cell in the body; these hormones help regulate growth and chemical reactions.

In glaucoma, the optic nerve becomes progressively damaged and, if not treated, leads to loss of vision and even blindness.

The study authors suggested that the link between glaucoma and thyroid disorders may owe to chemical deposits in the blood vessels that circulate blood to the eye, causing an increase in pressure within the eyeball. Increased pressure in the eyeball is the main feature of glaucoma.

Dr. Andrew Iwach, a spokesman for the American Academy of Ophthalmology and executive director of the Glaucoma Center of San Francisco, said the potential link between thyroid problems and glaucoma is interesting and should be taken into account, but it still needs to be proven. The best advice is to get your eyes checked, he said.

"If you haven't seen an ophthalmologist by age 40, that's a great time to get a baseline exam," Iwach said.

"People may not know they are at risk for glaucoma. You are functioning fine, and yet slowly, this disease can chip away at the optic nerve, and by the time you have symptoms from glaucoma, oftentimes there's not really much we can do," he said.

Study Information

Jennifer Moren Cross, Christopher A Girkin, Cynthia Owsley, and Gerald McGwin Jr.
The Association between Thyroid Problems and Glaucoma
BJO
2008 October
University of Alabama at Birmingham, United States