Thyroid disorders could boost the risk of developing the eye disease glaucoma, according to research out today.
The study, published in the 'British Journal of Ophthalmology', found that people with glaucoma were 38% more likely to have had a thyroid disorder at some point in their life, than those without.
The report was based on statistics gathered in a sample of more than 12,000 adults in the USA, taking part in the 2002 National Health Interview Survey.
Participants were asked if they had ever been diagnosed with a disorder of the thyroid gland and/or the eye disease glaucoma.
The proportion of those with glaucoma who said they had had a thyroid problem was 6.5%, compared to 4.4% who had not.
After taking account of risk factors, including gender, race and smoking habits, the association between glaucoma and thyroid problems remained significant.
The thyroid makes hormones essential for the function of every cell in the body. These hormones help regulate growth and the rate of chemical reactions.
Glaucoma is characterised by progressive damage to the optic nerve. If left untreated, it leads to loss of detailed vision, and blindness.
The report, written by Dr Gerald McGwin at the University of Birmingham, Alabama, US, found that a biological link between the two conditions was plausible. An underactive thyroid can promote chemical deposits in the mesh of vessels serving the eye, which can spark an increase in pressure within the eyeball. This is a common feature of glaucoma.
The study concludes: “Research based on a large clinical sample is warranted on the development of glaucoma and thyroid disorders to ascertain more definitively whether thyroid problems instigate and/or exacerbate glaucomatous damage.”