Crohn's Disease Eyes

Introduction

Crohn’s disease is one of the two types of inflammatory bowel diseases (IBD) which, apart from affecting the digestive tract, have an impact outside the gut as well.¹ These are called extra intestinal manifestations, and include effects on the eyes, joints, and skin. This article will further focus on the effects of Crohn’s disease on the eyes.

About Crohn’s Disease

What is Crohn’s Disease?

Crohn’s disease is a lifelong condition characterised by inflammation of the digestive tract. Any site from the mouth to the anus is at risk of being affected. It often involves periods of active inflammation called “flare-ups” in-between periods of no symptoms, yet it is not caused by an infection. In the UK, Crohn’s disease occurs in 157 people in every 100,000¹ and got its name in 1932 by Dr. Burrill Crohn who first described it.²

Causes and Risk Factors?

The cause of the disease is unknown, but relatives of people with Crohn’s disease as well as smokers are more likely to develop the condition. Additionally, it has been said that an imbalance in the good versus bad flora in the intestine may play a big part in IBD susceptibility.³  People of Jewish origin are also believed to have a higher risk of developing the disease than the general population.

Symptoms

Crohn’s disease has various manifestations. While symptoms mainly occur within the digestive tract, others are also present. These include, but are not limited to: 

• Diarrhoea;
• Abdominal pain;
• Weight loss; 
• Nausea and vomiting.⁴

Up to half of the people with IBD experience at least one symptom outside the gut. Sometimes these even occur before the diagnosis of IBD.⁵ One such symptom is found in the eyes.

Eye conditions and Crohn’s Disease

Not every red eye is caused by conjunctivitis. Inflammation of any part of the eye can produce an eye that looks red. These following conditions can occur due to Crohn’s disease affecting the eyes, but they can also occur in the absence of Crohn’s disease.

Episcleritis

This is an inflammation of the episclera. The episclera is a thin layer between the conjunctiva (the surface of the eyeball) and the sclera (the white of the eye). It presents as a red, irritated eye. Whilst It does not affect vision, there may be mild pain.⁵

Scleritis

The sclera is the white part of the eye. Inflammation of the sclera is a rare but serious eye complication. Pain is more severe than that experienced during episcleritis. It can result in blurred vision or sensitivity to light.⁵

Uveitis

The uvea or uveal tract is made up of the iris, ciliary body, and choroid. The iris is the part of the eye that gives your eyes their distinctive colour. The ciliary body is found between the iris and choroid, and produces the liquid of the eye called aqueous humour. The choroid is located between the sclera and the retina. Uveitis comprises an inflammation of any of these components. It is a rare but serious eye complication and, like scleritis, presents with pain, blurred vision, and sensitivity to light.

Keratopathy

This is a broad term describing diseases of the cornea. This could include corneal ulcers or abrasions or inflammation. The cornea is the transparent part of the eye lying over the iris and pupil. Inflammation of the cornea is called keratitis. It can cause a red eye, gritty sensation during eye movement, and sensitivity to light.

Dry eye

This occurs when the tears produced by the tear glands are not enough to moisturise the eyes. It is characterised by redness, stinging, and teariness of the eyes.

Diagnosis

A suspicion of Crohn’s disease can be determined from the history of recurrent bloody diarrhoea, abdominal pain, and examination for features of extra-intestinal manifestations. A definitive diagnosis is made through a procedure called a colonoscopy.⁷ This involves passing a camera-fitted tube through the anus to visualise the gut. The inflamed gut will be visible and some tissue could be taken for examination under the microscope. This procedure is called a biopsy.⁸

The other type of inflammatory bowel disease is called ulcerative colitis.⁹ Its features are similar to Crohn’s disease. The main difference is in the parts of the gut it commonly affects; unlike ulcerative colitis, the inflammation in Crohn’s disease usually affects the full thickness of the gut wall. However, these can overlap, and therefore a biopsy may be necessary to differentiate between the two and diagnose effectively. 

Diagnosis of eye presentations would be based on history and severity of red eye pain, presence of disturbance of vision, and an examination of the eye.

Treatments

Treatment of Crohn’s disease involves drugs such as steroids and immunosuppressants. It has been estimated that 50-80% of Crohn’s sufferers will be in need of surgery at some point.¹

Episcleritis may resolve without treatment. The doctor might recommend eye drops or tablets containing anti-inflammatory agents or steroids. Scleritis and uveitis are treated by ophthalmologists (eye doctors). Steroid eye drops may be used or those that suppress the immune system.⁵

Tips for risk reduction

Lifestyle factors, such as drinking and smoking, may be significant factors in the treatment and management of IBD and Chrohn’s disease. Quitting smoking and reducing alcohol consumption have been shown to reduce the frequency of flare-ups in Crohn’s disease. Furthermore, eating a healthy and balanced diet that avoids foods that you know to be triggers will help you live with the disease more comfortably.

Summary

The eyes are commonly affected by Crohn’s disease. The exact causes and risk factors are not yet known, but there is an understanding that those who smoke or have a relative with Crohn's disease are more likely to go on to develop the condition. When the eyes are affected, it can lead to conditions rising, such as episcleritis, scleritis, uveitis, keratopathy, and dry eye. Seek urgent medical help if you have been diagnosed with Crohn’s disease and develop a red, painful eye. Treatment options include prescription of steroids and immunosuppressants, as well as eventual surgery.