With all the steps you take to control the gastrointestinal effects of Crohn's disease, your eyes may be the last area you'd expect to be affected. Yet as many as 12 percent of people with Crohn’s disease experience eye complications, according to a research review published in March 2016 in the Journal of Crohn’s and Colitis.

“The tissues that [make up] the eye are very similar to tissues in other parts of the body, so inflammatory diseases that affect other organs, such as the bowel in Crohn’s disease, will affect the eye as well,” explains Calvin Roberts, MD, a clinical professor of ophthalmology at Weill Cornell Medicine and the chief medical officer at Bausch and Lomb.

The connection between Crohn’s and your eyes also comes down to the way your immune system behaves. “With Crohn’s, the body attacks the eye similarly to the way it attacks the tissue in the gastrointestinal tract,” says Paul J. Dougherty, MD, the medical director of Dougherty Laser Vision in Los Angeles and a clinical instructor of ophthalmology at UCLA’s Jules Stein Eye Institute.

Because the eyes are so sensitive — think of how much irritation a tiny eyelash can cause if it gets into your eye — eye problems in Crohn’s may show up before the gastrointestinal symptoms of inflammation set in. So if you have repeated episodes of eye inflammation, get screened for Crohn’s disease, suggests Dr. Roberts.

Complicating the situation further, some Crohn’s disease treatments can contribute to eye conditions as well. “Oral steroids are frequently used in the treatment of Crohn’s, and steroids can cause both glaucoma, high pressure in the eye, and cataract, which is a cloudy lens,” says Dr. Dougherty.

Different Eye Complications in Crohn’s Disease

Here’s what you need to know about specific eye problems associated with Crohn’s.

Uveitis One of the most common eye problems in Crohn’s, according to the Crohn's & Colitis Foundation, uveitis is inflammation of the uvea — “a blood-vessel-rich lining inside the eye that brings nutrition to the cornea, retina, iris, and lens,” Roberts says. “When inflamed, the uvea becomes swollen, the retina swells, and vision becomes blurred.” The blurry vision associated with uveitis may strike suddenly or come on gradually, he says.

An ophthalmologist can diagnose uveitis with a slit lamp, which is a microscope that examines the inside of your eye. This painless exam is important because if left untreated, uveitis can lead to glaucoma — an eye disease that causes pressure within the eyeball and can potentially lead to vision loss, explains Dougherty.

Episcleritis Another common eye complication in Crohn’s disease is episcleritis, or inflammation of the outer coating of the white area of your eye, according to the Crohn's & Colitis Foundation. “When people have active Crohn’s disease, episcleritis also seems to flare — there is a clear relationship,” Dougherty notes. Symptoms of episcleritis include generalized or local redness of the eyes and mild soreness or discomfort, according to Johns Hopkins Medicine.

Dry eyes Dry eye syndrome, also called keratoconjunctivitis sicca (KCS), is an eye complication associated with Crohn’s that’s caused by reduced tear production or increased tear film evaporation, according to the Crohn’s & Colitis Foundation. Dry eyes can lead to itching, burning, or infection. Dougherty says that a few mechanisms can lead to this eye complication in Crohn’s, including the same inflammation that irritates the GI tract. But also, “with Crohn’s disease, many people get malabsorption of nutrients, including vitamin A, and without enough vitamin A, you can get dry eye syndrome or, in severe cases, night blindness,” he says.

Keratopathy Another eye condition associated with Crohn’s disease is keratopathy, an abnormality of the cornea in which white deposits form, according to the Crohn's & Colitis Foundation. It may result from uveitis or dry eyes. An ophthalmologist can diagnose keratopathy with a slit lamp exam.

Uveitis and episcleritis are usually treated with steroid eye drops, used frequently during the day, Roberts says. “Most patients respond to eye drops, but those who do not may require corticosteroids taken by mouth or other anti-inflammatory medications,” he adds.

Treatments for dry eye syndrome may include artificial tears or eye drops containing cyclosporine, a drug to reduce inflammation caused by dryness.

If keratopathy is advanced or bothersome enough to require taking action, it may be treated with eye drops containing a calcium binding agent and a procedure that involves scraping the surface of the cornea, according to Columbia University’s Department of Ophthalmology.

Lowering Your Risk for Crohn’s Eye Problems

Because the inflammatory process in the eye is similar to the process in the bowel, episodes of eye inflammation tend to coincide with Crohn’s GI flare-ups, says Roberts. “So the same advice given to deter bowel relapses applies to eye flares. Avoid tobacco and caffeine, and decrease stress to the bowel by eating smaller, more balanced meals,” he suggests.

Roberts also stresses the importance of routine eye examinations, both to look for eye problems in Crohn’s and for your general wellness. “A comprehensive eye examination will not only detect problems in your eye like uveitis, it can also be an important indicator of overall health,” he says. “Changes that may be slowly evolving in the body often present themselves within the eye’s fragile structure first, and can be found during a routine eye exam.”

Eye checkups should be more frequent when you have Crohn’s, says Dougherty. “A person with Crohn’s disease who is taking steroids should have an eye exam every 6 to 12 months,” he recommends.

To protect your vision, see your eye care professional as soon as any unusual eye symptoms arise, and also discuss how often you’ll need different types of eye screening. “Risk factors that can elevate your need for an eye health exam include a family history of eye disease — especially macular degeneration or glaucoma — obesity, smoking, and diabetes,” Roberts notes.

Additional reporting by Quinn Phillips.