Scleritis

Scleritis is a serious cause of red eye because the inflammation is deep in the sclera, the tough white outer coat of the eye. The pain is often severe, aching, or radiating into the brow, jaw, or temple, and may wake patients at night. Compared with episcleritis, scleritis is more serious and more strongly associated with systemic autoimmune disease. A violaceous or bluish-purple hue can help distinguish it from more superficial redness.

How Scleritis Differs From Other Causes of Red Eye

Scleritis is one of the conditions a clinician thinks of when someone presents with a red eye that hurts. Unlike conjunctivitis, where the eye is uncomfortable but not deeply painful, scleritis produces a deep, boring pain that wakes the patient from sleep, worsens with eye movement, and is often poorly relieved by ordinary analgesics. The eye looks differently red, too - the inflamed scleral vessels lie deeper than the surface conjunctival vessels, and the resulting hue is more violet or maroon than the bright pink of conjunctivitis.

Episcleritis, by comparison, is a much milder inflammation of the thin episclera. It is uncomfortable but not severely painful, the redness is more sectoral and brighter, and the natural history is benign and self-limited.

Symptoms

• Severe, deep, boring eye pain - often the dominant complaint
• Pain frequently worse at night and on eye movement
• Pain may radiate to the brow, temple, jaw, or sinus
• Tenderness to touch through the closed eyelid
• Violaceous (bluish-purple) redness of the affected area, when present
• Photophobia
• Watery eyes
• Blurred vision in more severe cases
• May be unilateral or bilateral
• Often recurrent - patients with one episode are at risk for further episodes

Types of Scleritis

Scleritis is classified by location and pattern, and the type guides both prognosis and treatment.

Anterior Scleritis (most common, ~90-95% of cases)

Diffuse anterior scleritis

• Widespread inflammation of the front portion of the sclera
• Deep redness over a broad area
• Most common form
• Usually responds to systemic NSAIDs

Nodular anterior scleritis

• A discrete, tender, immobile nodule on the sclera
• Distinguishable from a mobile episcleritis nodule by its fixed position
• Often responds to oral NSAIDs but may require steroids

Necrotizing scleritis with inflammation

• The most severe form
• Areas of scleral thinning, avascular patches, and tissue destruction
• Strongly associated with systemic vasculitis - most notably granulomatosis with polyangiitis
• Can be associated with serious systemic vasculitis; systemic risk depends on the underlying disease
• Requires aggressive systemic immunosuppression

Necrotizing scleritis without inflammation (scleromalacia perforans)

• Painless scleral thinning, classically in long-standing rheumatoid arthritis
• Translucent sclera reveals the underlying dark choroid (uveal show); progression to actual perforation occurs but is not inevitable
• Despite the lack of pain, this is a serious sign of systemic disease

Posterior Scleritis

Inflammation of the back of the sclera, behind the equator of the eye. Less common but easily missed because the visible white of the eye looks normal. Typical features:

• Eye pain and ache
• Pain worse with eye movement
• Bulging eye (proptosis) in some cases
• Vision change from associated retinal involvement
• B-scan ultrasound shows the characteristic "T-sign" - fluid in the sub-Tenon space (the potential space between the sclera and Tenon's capsule, the fibrovascular sheath enveloping the globe) and a thickened scleral wall
• May be confused with orbital inflammatory disease or orbital tumor

Causes

Scleritis is most often part of a systemic disease, although a substantial minority of cases remain idiopathic.

Autoimmune and Connective Tissue Diseases (most common)

• Rheumatoid arthritis - the single most common systemic association
• Granulomatosis with polyangiitis (Wegener's) - strongly associated with necrotizing scleritis
• Polyarteritis nodosa, microscopic polyangiitis, eosinophilic granulomatosis with polyangiitis (Churg-Strauss)
• Systemic lupus erythematosus
• Relapsing polychondritis
• Inflammatory bowel disease (ulcerative colitis, Crohn's)
• Spondyloarthropathies

Infectious

• Herpes simplex and varicella zoster (especially after a herpes zoster ophthalmicus episode)
• Tuberculosis
• Syphilis
• Bacterial scleritis after surgery - Pseudomonas, atypical mycobacteria, Nocardia, Staphylococcus, Streptococcus, and fungal organisms are reported, particularly after pterygium surgery
• Lyme disease in endemic areas

Surgically Induced

• Following pterygium surgery, retinal surgery, or other ocular operations - typically appearing days to months postoperatively at the surgical site

Idiopathic

• A substantial minority of cases have no identifiable systemic or infectious cause despite full workup

Diagnosis

Examination

A thorough slit lamp examination is the foundation. The clinician looks at:

• The depth of the inflamed vessels (deep scleral, not just superficial conjunctival)
• The color (violaceous tint of true scleritis)
• The response to topical phenylephrine - episcleritis blanches; scleritis does not
• Areas of scleral thinning or avascularity
• Anterior chamber inflammation, keratic precipitates, and posterior involvement

B-Scan Ultrasound

B-scan ultrasound is a key test when posterior scleritis is suspected. The classic "T-sign" - fluid in the sub-Tenon space behind the eye - strongly supports the diagnosis when the visible sclera looks normal.

Imaging

• MRI of the orbits in suspected posterior scleritis
• CT in suspected sinus involvement (granulomatosis with polyangiitis)

Systemic Workup

A systemic disease workup is usually ordered for scleritis, tailored to the presentation and history:

• Blood tests: CBC, basic chemistry, ESR, CRP, ANA, ANCA panel (c-ANCA / p-ANCA), rheumatoid factor, anti-CCP, complement levels
• Autoantibody panels tailored to clinical suspicion
• Syphilis serology, tuberculosis testing
• HLA-B27 in suspected spondyloarthropathy
• Urinalysis (renal involvement in vasculitis)
• Chest imaging when granulomatosis with polyangiitis is suspected
• HIV testing in selected patients

A delay in identifying the underlying systemic disease can have life-threatening consequences when vasculitis is involved.

Treatment

Treatment is matched to severity:

Mild to Moderate Anterior Scleritis

• Oral NSAIDs - commonly first-line for non-necrotizing anterior disease. Typical agents include ibuprofen, naproxen, indomethacin, or selective COX-2 inhibitors
• Topical drops are generally inadequate alone

Moderate to Severe or NSAID-Refractory

• Systemic corticosteroids - oral prednisone, with taper over weeks to months
• For severe cases, IV steroids may be used initially
• Steroid-sparing immunosuppressants for chronic disease - methotrexate, mycophenolate, azathioprine, or systemic cyclosporine in selected cases
• Biologics - rituximab, infliximab, or other agents targeted to the underlying systemic disease

Necrotizing Scleritis

• Treatment is up-front combined therapy (rather than NSAID-first stepwise escalation), pairing high-dose steroid with a steroid-sparing immunosuppressant
• For granulomatosis-with-polyangiitis-associated necrotizing scleritis, rituximab or cyclophosphamide-based regimens may be considered with rheumatology, depending on organ involvement, severity, relapse status, and patient factors
• Coordinated care with rheumatology is essential
• Surgical patching with donor scleral or amniotic graft for impending or actual perforation

Posterior Scleritis

• Oral NSAIDs for milder cases
• Systemic steroids for moderate-to-severe involvement
• Treat associated systemic disease

Episcleritis vs. Scleritis Treatment

Episcleritis often resolves with no treatment, topical lubricants, or short courses of topical NSAIDs / mild steroids. Scleritis requires systemic medication. This is one of the practical reasons telling the two apart matters.

Prognosis

Most anterior scleritis can be controlled with appropriate treatment, although recurrences are common and many patients require chronic suppressive therapy. Outcomes depend heavily on the underlying systemic disease:

• Idiopathic scleritis - generally good visual prognosis with treatment
• Rheumatoid scleritis - controllable but reflects active systemic disease
• Granulomatosis with polyangiitis - historically associated with significant mortality from systemic disease; modern immunosuppression has substantially improved survival
• Necrotizing scleritis - vision-threatening and life-threatening; mortality is often from the underlying vasculitis rather than the eye

Complications

• Peripheral ulcerative keratitis
• Uveitis
• Cataract formation (from chronic inflammation or chronic steroid use)
• Glaucoma
• Scleral thinning and perforation in severe cases
• Vision loss from any combination of the above

Frequently Asked Questions

How is scleritis different from pink eye?

Pink eye (conjunctivitis) is a surface inflammation that is uncomfortable but rarely severely painful. Scleritis is a deeper inflammation that often produces severe boring pain, may have a more bluish-purple color, and frequently requires systemic treatment rather than surface drops alone. The two are distinguished at a slit lamp examination and by the response to topical phenylephrine drops.

Is scleritis an emergency?

Severe scleritis - particularly necrotizing scleritis - is urgent. Most cases benefit from prompt evaluation rather than waiting weeks. The eye itself is at moderate risk of vision loss in many cases, but the more important reason for prompt evaluation is to identify the underlying systemic disease, which may need urgent treatment.

Will I need lifelong medication?

Many patients with scleritis associated with an underlying chronic disease (rheumatoid arthritis, GPA, etc.) require long-term immunosuppression to keep both the eye and the systemic disease quiet. Patients with idiopathic scleritis may be able to taper off therapy after the disease has been quiet for a year or more.

Can scleritis cause blindness?

Yes, although this is uncommon in mild cases with appropriate treatment. Vision loss can come from corneal involvement, cataract, glaucoma, retinal involvement in posterior scleritis, or scleral perforation in necrotizing disease.

Why am I being sent to a rheumatologist?

Because roughly 40-50% of scleritis cases are part of a systemic autoimmune disease that affects organs beyond the eye. A rheumatologist can identify and manage the underlying condition, choose immunosuppressive therapy when needed, and help coordinate long-term care. This collaboration is one of the most important reasons scleritis is taken seriously.

References