Thyroid problems appear to increase the likelihood of developing of glaucoma by nearly 40 per cent, according to a brief report in the British Journal of Ophthalmology.

Glaucoma is a leading cause of visual impairment worldwide. In open-angle glaucoma, the most common type, fluid cannot drain properly from the eyeball, leading to increased pressure within the eye and damage to the optic nerve. It may be treated with medication to lower pressure in the eye, and surgery may be performed to restore normal drainage.

The study findings come from an analysis of data for more than 12,000 US adults who took part in the 2002 National Health Interview Survey.

Overall, 4.6 per cent of subjects reported having glaucoma and 11.9 per cent reported a history of thyroid problems, lead author J. M. Cross, from the University of Alabama, Birmingham, and colleagues note.

Glaucoma was present in 6.5 per cent of subjects with thyroid problems and in 4.4 per cent of subjects without them. After accounting for age, gender, race, and smoking status, thyroid problems were associated with a 38-per cent increased risk of glaucoma, the report indicates.

"The association between thyroid disorders and the development of glaucoma is important to establish, given the high prevalence of both conditions in the general population," the authors conclude. Thus, data from larger, forward-looking studies is needed to determine whether thyroid problems instigate or worsen glaucoma, they add.

SOURCE: British Journal of Ophthalmology, October 16th online, 2008.