What is the diagnosis and management of a patient with ankylosing spondylitis (AS) presenting with redness, photophobia, and blurred vision in one eye?

Diagnosis and Management of Acute Anterior Uveitis in Ankylosing Spondylitis

a. Likely Diagnosis and Definition

This patient has acute anterior uveitis (AAU), an inflammatory disorder of the iris and ciliary body that presents with sudden-onset, typically unilateral inflammation of the anterior structures of the eye. 1, 2

• AAU is the most common extra-articular manifestation of ankylosing spondylitis, occurring in approximately 40% of AS patients during their disease course 1
• The condition is characterized by inflammation of the iris and ciliary body (iritis and iridocyclitis) 3
• The recurrent nature (previous episode 1 year ago) and unilateral presentation are typical features of HLA-B27-associated AAU 2, 4

b. Clinical Features and Complications

Clinical Features

• Sudden onset of unilateral eye pain, redness (circumcorneal congestion), photophobia, and blurred vision 1, 3
• Anterior chamber cells visible on slit-lamp examination (as seen in this patient) 4
• Episodes are typically short-lived if treated appropriately with corticosteroids 2
• Attacks tend to alternate between eyes in bilateral cases, though unilateral involvement (55.2%) is more common than bilateral (45.3%) 4
• Hypopyon may develop in severe cases (approximately 10% of cases) 4

Complications

• Posterior synechiae (iris adhesions to the lens) - occurs in approximately 14% of cases 4
• Secondary cataract formation - develops in approximately 7% of cases 4
• Secondary glaucoma - occurs in approximately 4% of cases 4
• Cystoid macular edema - seen in approximately 3% of cases 4
• Anterior vitreous cells indicating spillover inflammation - occurs in approximately 8% of cases 4
• Permanent vision loss if untreated or inadequately managed 3
• Band keratopathy and corneal degeneration in chronic cases 4

c. Differential Diagnosis

Primary Differential Considerations

HLA-B27-associated conditions:

• Other spondyloarthropathies (reactive arthritis/Reiter's syndrome, psoriatic arthritis, inflammatory bowel disease-associated arthritis) 2, 3
• Idiopathic HLA-B27-positive AAU without systemic disease 2

Infectious causes:

• Herpetic uveitis (herpes simplex or varicella-zoster virus)
• Syphilitic uveitis
• Tuberculosis-associated uveitis
• Lyme disease-associated uveitis

Other inflammatory conditions:

• Behçet's disease (typically bilateral with hypopyon) 5
• Sarcoidosis (usually presents with granulomatous inflammation)
• Juvenile idiopathic arthritis-associated uveitis (chronic, insidious onset, typically in children) 6
• Fuchs heterochromic iridocyclitis (chronic, painless)

Key distinguishing features: The sudden onset, unilateral presentation, recurrent nature, and known AS diagnosis make HLA-B27-associated AAU the most likely diagnosis, distinguishing it from chronic granulomatous uveitis or bilateral conditions like Behçet's disease 1, 2

d. Management Approach

Immediate Ophthalmologic Management

Initiate topical corticosteroids and mydriatic/cycloplegic agents immediately - this is the cornerstone of treatment for AAU 6, 5, 1

• Topical prednisolone acetate 1% every 1-2 hours initially, then taper based on response 5
• Cycloplegic agents (cyclopentolate 1% or atropine 1%) to prevent posterior synechiae formation and relieve ciliary spasm 6, 3
• Most cases respond well within days to weeks with this regimen 1, 3

Systemic Therapy Considerations

Continue current ankylosing spondylitis treatment if the AS is otherwise well-controlled - do not immediately switch systemic therapy 6

• For isolated AAU episodes in patients with otherwise controlled AS, topical therapy alone is usually sufficient 1
• Oral corticosteroids are reserved for severe, bilateral, or refractory cases, particularly those with associated inflammatory bowel disease or chronic inflammation 1
• Short courses (typically 1-2 weeks) are adequate when systemic steroids are needed 1

When to Escalate Systemic Therapy

For recurrent or refractory AAU despite adequate topical therapy, consider monoclonal antibody TNF inhibitors (adalimumab or infliximab) over other biologics 6, 5

• Monoclonal antibody TNF inhibitors are more effective than etanercept in reducing AAU recurrence 6
• The risk of first AAU is significantly higher with secukinumab (OR 2.32) and etanercept (OR 1.82) compared to adalimumab 6
• No significant differences exist between golimumab, certolizumab pegol, or infliximab compared to adalimumab 6

Monitoring and Follow-up

Ophthalmologic examination within 24-48 hours of presentation, then every 1-2 weeks during active inflammation 5

• Monitor for complications including posterior synechiae, elevated intraocular pressure, and cataract formation 4
• Once controlled on stable topical therapy, monitor every 3 months 5
• When tapering topical corticosteroids, follow up within one month after each change 5

Management of Underlying AS

Optimize AS treatment with NSAIDs and structured exercise program 6, 7

• Continue NSAIDs at the lowest effective dose for AS management 6, 7
• Ensure patient is enrolled in a structured exercise program, as this is essential for all AS patients 6, 7
• If AS disease activity is high despite NSAIDs, consider referral to rheumatology for biologic therapy 7

Patient Education

Educate the patient about warning signs of AAU recurrence (eye pain, redness, photophobia) to enable early treatment and prevent complications 6

• Approximately 40% of AS patients will experience AAU during their disease course 1
• Early recognition and treatment significantly improve outcomes 1
• Instruct patient to seek immediate ophthalmologic care if symptoms recur 6

Prognosis

The prognosis is generally good with appropriate treatment - most patients achieve complete resolution without permanent visual impairment 4

• Vision typically returns to baseline with prompt treatment 4
• Recurrence is common but manageable with the same treatment approach 1
• Complications are preventable with early aggressive topical therapy 3, 4