For people with uveitis, keeping vitamin D levels in a healthy range could help prevent flare ups, new research suggests.
Painful, light-sensitive eyes and trouble seeing clearly can certainly make life difficult. Uveitis is inflammation of the eyeball, specifically the uvea - a layer of blood vessels that coats the inside of the eye.
The uvea includes the iris (the coloured circle of the eye, which helps control the amount of light entering the eye), the ciliary body (which helps the eye focus and provides nutrients to keep the eye healthy) and the choroid (which is full of blood vessels that nourish the retina).
When this part of the eye becomes inflamed, it can result in redness, pain, floaters, sensitivity to light and blurred vision. In serious cases, it can damage vital eye tissue, leading to permanent vision loss.
Uveitis is relatively uncommon - in Australia, it affects only around 20 people per 100,000 each year. However, it can affect people of all ages, from small children right through to the elderly. It can affect just one eye or both at once, and can be acute or chronic.
What causes uveitis?
There are a number of things that can cause uveitis, including infections and eye injuries. But in Australia and other developed countries, most cases are caused by an autoimmune response.
"Autoimmune diseases are when your immune system attacks a part of your body in a case of mistaken identity," explains Associate Professor Lyndell Lim, a uveitis and medical retina subspecialist and Head of Clinical Trials Research at CERA.
"In uveitis, the immune system decides to fight the eye. Like many autoimmune conditions, there's a lot we don't know about the causes of uveitis, and there is currently no cure. We only know how to manage and control it until it goes into remission."
Uveitis can be managed with anti-inflammatory or immunosuppressant medications, which can come in the form of eye drops, pills or injections. Treatment is aimed at reducing inflammation and pain, preventing further tissue damage and preserving vision.
Vitamin D deficiency and uveitis
Associate Professor Lyndell Lim
"When a patient with uveitis asks me what they can do to help their condition, the first thing I say is to stop smoking, if they smoke," says Associate Professor Lim.
"Next, I'd say let's check your vitamin D levels."
This is because new research from CERA and Monash University, published in Ophthalmology, suggests a link between vitamin D deficiency and relapses of uveitis.
Associate Professor Lim says the idea was based on previous studies that have linked vitamin D and multiple sclerosis.
"Vitamin D is so easily accessible, and easily measured. Studies have suggested that vitamin D deficiency might make you more prone to getting multiple sclerosis. As there's a link between multiple sclerosis and uveitis, we decided to study vitamin D in uveitis patients."
For the study, the researchers compared serum vitamin D levels, sunlight exposure and dietary intake in adult patients with active and inactive uveitis, as well as in population controls. 151 patients were involved in the study.
"We found that patients with uveitis were more likely to have low levels of vitamin D. More significantly, patients with active uveitis were more likely to have even lower levels of vitamin D," Associate Professor Lim says.
Vitamin D supplementation was found to be associated with decreased uveitis activity, as was sun exposure in those with vitamin D deficiency. These results suggest vitamin D supplementation should be studied as an option for the prevention of uveitis relapse in at-risk patients.
"More research is needed before we could recommend vitamin D supplements - there would need to be a randomised controlled trial," Associate Professor Lim says.
"But the message is, if you have uveitis, get your vitamin D levels checked, and if you're deficient it's worth trying to get your levels up into a healthy range."
