What is the correlation between irritable bowel disease (IBD) and uveitis or eye symptoms?

Correlation Between Inflammatory Bowel Disease and Uveitis/Eye Symptoms

Ocular manifestations occur in 4-12% of patients with inflammatory bowel disease (IBD), with uveitis, episcleritis, and scleritis being the most clinically significant extra-intestinal manifestations that require prompt recognition and ophthalmologic referral to prevent vision loss. 1

Epidemiology and Prevalence

• The reported incidence of ocular manifestations ranges from 4-12% of IBD cases, though some tertiary center cohorts report rates as high as 29% (likely overestimates due to referral bias). 1
• Patients with IBD are significantly more likely to experience ocular symptoms compared to controls, even in community-based studies. 1
• Ocular involvement is more prevalent in Crohn's disease than ulcerative colitis, particularly for episcleritis. 2, 3
• In a recent cohort study, 3.7% of IBD patients had confirmed ocular extra-intestinal manifestations, with inflammatory surface pathologies (33.2%) and uveitis (14.9%) being most common. 4

Pathophysiology

Ocular manifestations represent diverse immune-mediated pathologies involving activation and infiltration of both innate and adaptive immune cells into ocular tissues. 1

• Genetic associations include NOD2 mutations and MICA on MHC class I, supporting innate immune activation in uveitis pathogenesis. 1
• In severe cases, scleritis may be associated with fibrinoid necrosis and vasculitis. 1

Specific Ocular Manifestations

Episcleritis

• Episcleritis is the most common ocular extra-intestinal manifestation of IBD and typically correlates with bowel disease activity. 5, 3
• Clinical presentation includes mild or no pain, hyperemia of superficial conjunctival and episcleral vessels, itching, and burning sensation without visual changes. 1, 5
• Episcleritis may self-resolve and often responds to management of the underlying bowel disease. 1

Uveitis

• Uveitis is less common but has potentially more severe consequences, including risk of permanent vision loss. 1
• When related to Crohn's disease, uveitis is frequently bilateral, insidious in onset, and long-lasting. 1, 6
• Classical symptoms include eye pain, blurred vision, photophobia, and headache. 1, 6
• Critical distinction: Unlike episcleritis, uveitis can occur independently of bowel disease activity and may even precede the onset of intestinal symptoms. 1, 7

Scleritis

• Scleritis presents with severe pain, deep vessel involvement, and potential vision loss, distinguishing it from the milder episcleritis. 5, 8
• Visual disturbance, photophobia, or moderate to severe pain should prompt urgent ophthalmologic referral. 1, 6

Clinical Approach and Red Flags

When to Suspect Ocular Involvement

• Any IBD patient complaining of eye symptoms warrants careful evaluation, as symptoms are often nonspecific. 6, 7
• Episcleritis often occurs during IBD flares, while uveitis presents independently of intestinal disease activity. 1, 5, 3

Urgent Referral Criteria

Immediate ophthalmologic referral is required for:

• Visual disturbance or blurred vision 1, 6
• Photophobia 1
• Moderate to severe eye pain (suggests scleritis or uveitis, not episcleritis) 1, 5
• Any concern for uveitis or scleritis, as progression to permanent vision loss can occur without prompt treatment. 6, 8

Diagnostic Evaluation

• Slit-lamp examination by an ophthalmologist is essential to confirm diagnosis and differentiate between anterior and posterior uveitis, episcleritis, and scleritis. 1
• For uveitis, both the SUN guidelines and International Uveitis Study Group (IUSG) criteria are useful for disease classification. 1

Treatment Approach

Episcleritis

• Topical or systemic NSAIDs or topical corticosteroids can be used for symptomatic treatment. 1
• Treatment of the underlying bowel disease is the primary approach, as episcleritis often resolves with IBD control. 1

Uveitis

• Anterior uveitis should be treated with topical corticosteroids and cycloplegics. 1
• Treatment must be guided by an ophthalmologist with expertise in ocular inflammation. 1
• For refractory uveitis, systemic corticosteroids, conventional immunosuppressants, or anti-TNF agents are indicated. 1

Scleritis

• Scleritis requires systemic treatment including topical or systemic corticosteroids, conventional immunosuppressants, and anti-TNF agents. 1
• For necrotizing scleritis or refractory cases, immediate high-dose systemic corticosteroids plus disease-modifying antirheumatic drugs (DMARDs) are required. 8
• Anti-TNF agents (infliximab or adalimumab) are recommended when conventional DMARDs fail or for severe necrotizing scleritis. 8

Common Pitfalls

• Do not dismiss mild eye symptoms as insignificant—even episcleritis warrants evaluation and may indicate IBD flare. 5, 3
• Do not confuse episcleritis with scleritis—the presence of severe pain immediately raises concern for scleritis, which requires urgent systemic treatment. 5, 8
• Do not delay ophthalmologic referral for suspected uveitis or scleritis—these conditions can progress rapidly to permanent vision loss. 6, 8
• Be aware of iatrogenic ocular complications: corticosteroids may cause cataracts and glaucoma, while methotrexate can cause conjunctivitis and blepharitis. 9
• Recognize that anti-TNF agents, while effective for both IBD and uveitis, may paradoxically increase the risk of acute uveitis flares in some patients. 9