While Crohn’s disease is usually linked to gastrointestinal symptoms, it can affect people in other ways, including the eyes.

Crohn’s disease is a type of inflammatory bowel disease that causes:

  • diarrhea
  • rectal bleeding
  • abdominal cramps
  • constipation

Crohn’s is one of two conditions classified as inflammatory bowel disease (IBD). The other type is ulcerative colitis (UC).

Generally, IBD is associated with digestive symptoms. However, up to 10% of people with Crohn’s also experience irritation and inflammation in one or both eyes.

Crohn’s-related eye disorders can be painful. In rare cases, they can lead to vision loss.

There are four main conditions related to Crohn’s that can affect the eyes.

1. Episcleritis

Your episclera is the tissue between the clear, outermost layer of the eye and the white part of your eye. Episcleritis, or the inflammation of this tissue, is the most common eye-related disorder in people with IBD, affecting 2% to 5%. Symptoms include:

  • redness with or without mild pain
  • tenderness upon touching
  • watery eyes

Episcleritis is less painful than uveitis and doesn’t produce blurred vision or light sensitivity.

2. Uveitis

The uvea is a layer of tissue underneath the white layer of your eye. It includes the colored part of your eye known as the iris.

Inflammation of the uvea is less common than episcleritis, but uveitis is more serious. In rare cases, it can lead to glaucoma and vision loss. It affects about 0.5% to 3.5% of people with IBD.

The main symptoms of uveitis are:

  • pain
  • blurred vision
  • sensitivity to light, known as photophobia
  • eye redness

Uveitis, along with IBD, is more common in women than in men. It’s also strongly associated with arthritis and abnormalities of the sacroiliac joint.

3. Keratopathy

Keratopathy is an umbrella term for several types of disorders of your cornea, the clear front surface of your eye. Symptoms include:

  • eye irritation
  • sensation that a foreign body is caught in your eye
  • reduced vision
  • eye watering
  • pain
  • light sensitivity

4. Dry eye

Dry eye, also known as keratoconjunctivitis, occurs when your eyes don’t produce enough tears. It can have many causes, including Crohn’s disease. It may make you feel as if you have sand in your eyes. Other symptoms include:

  • itching or stinging
  • burning
  • pain
  • eye redness

Other problems

In rare cases, you may develop inflammation in other parts of the eye, including the retina and optic nerve.

When Crohn’s disease shows symptoms outside of your gastrointestinal tract, they’re called extraintestinal manifestations (EIMs). Aside from the eyes, EIMs often occur in the skin, joints, and liver. EIMs occur in up to 25% to 40% of people with IBD.

The exact cause of ocular symptoms in Crohn’s disease isn’t known. But there’s growing evidence of a genetic component. A family history of IBD might raise your risk of eye inflammation, even if you don’t have IBD.

Your risk of developing eye symptoms increases if you have at least one other EIM.

In some cases, the medications you take for Crohn’s disease could cause symptoms in your eyes. Oral steroids frequently used to treat Crohn’s can cause eye problems, including glaucoma.

An eye doctor will take your medical history and perform a visual examination of your eyes to make a diagnosis.

Uveitis and keratopathy are confirmed by examination with a slit lamp. This is a high intensity light and microscope also used in routine eye exams. It’s a painless procedure.

Your specialist may apply drops containing a yellow dye to make the surface of your cornea more visible.

Episcleritis is the most common eye-related symptom of Crohn’s disease. It’s often present when Crohn’s is diagnosed. It may clear up with treatment of Crohn’s.

Cold compresses and topical steroids are occasionally required if it doesn’t clear up.

Uveitis is a more serious condition that requires prompt treatment with topical or systemic steroids. Drugs that dilate the pupil, such as atropine (Atropen) or tropicamide (Mydriacyl), are sometimes used to provide short-term relief. If left untreated, uveitis can develop into glaucoma and possible vision loss.

Mild keratopathy is treated with gels and lubricating fluids. In more serious cases, your doctor will prescribe medicated eye drops.

Eye complications associated with Crohn’s are usually mild. But some types of uveitis can be serious enough to cause glaucoma and even blindness if they’re not treated early.

Be sure to have regular yearly eye examinations and tell your doctor if you notice any eye irritations or vision problems.