Scleritis vs Episcleritis: Causes, Symptoms, Clinical Features, Diagnosis, and Treatment
Scleritis vs Episcleritis: Causes, Symptoms, Clinical Features, Diagnosis, and Treatment
Scleritis vs episcleritis is an important clinical distinction when evaluating a patient with a red eye. Both conditions involve inflammation of tissues surrounding the sclera, but they differ significantly in depth, severity, pain, causes, clinical appearance, complications, and treatment.
While episcleritis is usually a mild, self-limiting inflammation of the episclera, scleritis is a deeper and potentially sight-threatening inflammatory disorder involving the sclera.
Recognizing the difference is particularly important for optometry students, ophthalmology students, and clinicians, because a painful red eye should never automatically be assumed to be simple conjunctivitis.
What Is Episcleritis?
Episcleritis is an inflammation of the episclera, the thin layer of vascular connective tissue located between the conjunctiva and the underlying sclera.
It is generally a benign and self-limiting condition.
Episcleritis commonly presents with:
- Localized or diffuse eye redness
- Mild tenderness or discomfort
- Watery eyes
- Mild photophobia in some patients
- Normal or near-normal vision
In many cases, episcleritis resolves without serious complications.
What Is Scleritis?
Scleritis is inflammation of the scleral tissue itself.
It is deeper and generally more severe than episcleritis.
Scleritis can cause:
- Severe deep ocular pain
- Marked redness
- Tenderness
- Photophobia
- Tearing
- Blurred vision
- Pain around or behind the eye
Importantly, scleritis may be associated with systemic autoimmune or inflammatory disorders.
Because it can damage the sclera and other ocular structures, scleritis requires prompt clinical assessment.
Sclera vs Episclera: Where Does the Inflammation Occur?
Understanding the anatomy makes the difference easier to remember.
From superficial to deep:
Conjunctiva → Episclera → Sclera → Uveal tissues
Episcleritis
Inflammation is primarily located in the episclera.
Scleritis
Inflammation involves the deeper scleral tissue.
This difference in depth explains many of their clinical differences.
Causes of Episcleritis
Episcleritis is often idiopathic, meaning no specific underlying cause is identified.
However, it can occasionally be associated with systemic inflammatory or autoimmune conditions.
Possible associations include:
- Rheumatoid arthritis
- Systemic lupus erythematosus
- Inflammatory bowel disease
- Certain vasculitic disorders
- Gout
- Other systemic inflammatory conditions
Not every patient with episcleritis has an underlying systemic disease.
Causes of Scleritis
Scleritis is more strongly associated with systemic inflammatory disorders.
Important causes and associations include:
Autoimmune and inflammatory disorders
- Rheumatoid arthritis
- Granulomatosis with polyangiitis
- Systemic lupus erythematosus
- Relapsing polychondritis
- Polyarteritis nodosa
- Inflammatory bowel disease
- Other systemic vasculitic diseases
Infectious causes
Some cases may be associated with infection, including:
- Herpes zoster
- Syphilis
- Tuberculosis
- Bacterial infections
Trauma and surgery
Scleritis can occasionally occur after:
- Ocular trauma
- Ocular surgery
- Other local ocular insults
In some cases, however, no underlying cause is found.
Symptoms of Episcleritis
Typical symptoms of episcleritis include:
1. Eye redness
Redness is often the most noticeable feature.
It may affect:
- A small sector of the eye
- A larger portion of the eye
- Occasionally the entire visible episcleral surface
2. Mild discomfort
Patients may describe:
- Irritation
- Mild aching
- Tenderness
- Foreign-body sensation
Severe pain is unusual.
3. Watering
Mild lacrimation may occur.
4. Mild photophobia
Light sensitivity can occur but is generally less prominent than in more serious inflammatory eye diseases.
5. Vision usually remains normal
A key clinical clue is that uncomplicated episcleritis generally does not significantly reduce visual acuity.
Symptoms of Scleritis
Scleritis usually produces more significant symptoms.
1. Severe eye pain
Pain is one of the most important distinguishing features.
Patients may describe the pain as:
- Deep
- Severe
- Aching
- Boring
- Throbbing
Pain may radiate toward:
- Forehead
- Temple
- Face
- Jaw
It may also become worse with eye movement or during the night.
2. Deep ocular tenderness
The eye may be markedly tender.
The sensation is different from the mild irritation commonly associated with superficial ocular inflammation.
3. Redness
Scleral inflammation produces significant ocular redness.
The redness may appear:
- Deep red
- Dusky
- Violaceous or bluish-red
4. Photophobia
Patients may experience significant sensitivity to light.
5. Tearing
Reflex tearing may accompany inflammation.
6. Reduced vision
Unlike uncomplicated episcleritis, scleritis can affect visual acuity.
Reduced vision may occur because of associated:
- Keratitis
- Uveitis
- Glaucoma
- Cataract
- Retinal involvement
- Optic nerve involvement
Clinical Appearance of Episcleritis
Episcleritis often produces a bright red or pink area on the eye.
The inflammation may be:
Sectoral
A localized region is affected.
Diffuse
A broader area becomes red.
The vessels involved are superficial and tend to appear more clearly defined.
Clinical Appearance of Scleritis
Scleritis often produces a deep, dusky-red or violaceous appearance.
The redness may appear more diffuse and intense.
Because the inflammation is deeper, the scleral vessels may appear less sharply defined.
Severe cases may produce scleral thinning or areas of tissue destruction.
Phenylephrine Test: Episcleritis vs Scleritis
One traditional clinical method used to help differentiate superficial episcleral vessels from deeper scleral inflammation involves a topical vasoconstrictor such as phenylephrine.
Superficial episcleral vessels may blanch more readily.
Deep scleral vessels associated with scleritis generally do not blanch as readily.
Important point
This test should be interpreted in the context of the complete ocular examination rather than used as the sole diagnostic method.
Why Does Scleritis Cause More Pain?
The sclera contains sensory nerve fibers.
Inflammation involving deeper scleral tissues can stimulate these sensory nerves and produce substantial pain.
This is why:
Superficial inflammation → usually mild discomfort
whereas
Deep scleral inflammation → severe pain
is a useful clinical concept.
Scleritis Types
Scleritis can be broadly classified into:
- Anterior scleritis
- Posterior scleritis
Anterior Scleritis
This involves the anterior portion of the sclera and is the more commonly recognized form.
Subtypes include:
- Diffuse anterior scleritis
- Nodular anterior scleritis
- Necrotizing scleritis with inflammation
- Necrotizing scleritis without inflammation
Posterior Scleritis
Posterior scleritis affects the sclera behind the equator of the eyeball.
It may be more difficult to recognize because the inflammation is not always obvious externally.
Patients may present with:
- Deep eye pain
- Headache
- Reduced vision
- Pain with eye movement
- Choroidal effusion
- Exudative retinal detachment
- Optic disc swelling
Imaging such as B-scan ultrasonography can be very useful in suspected posterior scleritis.
A classic ultrasound finding is thickening of the posterior coats of the eye with fluid in the Tenon's space, producing the well-known T-sign.
Necrotizing Scleritis
Necrotizing scleritis is one of the most severe forms.
It can lead to:
- Scleral thinning
- Tissue destruction
- Severe inflammation
- Structural weakening
- Potential scleral perforation
- Significant visual loss
It may be strongly associated with systemic autoimmune or vasculitic disease.
This form requires urgent specialist management.
Nodular Scleritis
In nodular scleritis, a localized inflammatory nodule develops within the sclera.
Patients may have:
- Localized redness
- Significant pain
- A raised or tender scleral area
It can sometimes be confused with other causes of a localized ocular mass or inflammation.
Diagnosis of Episcleritis
Diagnosis is primarily clinical.
The ophthalmic examination may include:
Visual acuity
Usually normal.
Slit-lamp examination
Used to assess:
- Location of redness
- Vessel depth
- Cornea
- Anterior chamber
- Conjunctiva
- Episclera
Pupil examination
Helps identify associated intraocular disease.
Assessment of pain
The degree and character of pain are clinically important.
Diagnosis of Scleritis
Scleritis is diagnosed using a combination of:
- Detailed history
- Visual acuity
- Slit-lamp examination
- Ocular motility assessment
- Assessment of scleral tenderness
- Anterior segment examination
- Dilated fundus examination when indicated
- Ocular imaging when necessary
Additional investigations may be required when an underlying systemic disease is suspected.
Investigating Underlying Systemic Disease
Because scleritis can be associated with systemic inflammatory disease, clinicians may consider investigations based on the patient's history and examination.
Possible investigations can include:
- Complete blood count
- ESR
- CRP
- Rheumatoid factor
- Anti-CCP antibodies
- ANA
- ANCA
- Other autoimmune testing
- Syphilis testing
- Tuberculosis evaluation
- Chest imaging when clinically indicated
Testing should be guided by clinical suspicion, rather than ordering every test for every patient.
Treatment of Episcleritis
Most uncomplicated episcleritis resolves spontaneously.
Treatment may include:
1. Observation
If symptoms are mild, reassurance and observation may be sufficient.
2. Artificial tears
Lubricating eye drops may improve discomfort.
3. Cold compresses
Cool compresses may help reduce discomfort and redness.
4. Anti-inflammatory treatment
In more symptomatic cases, clinicians may consider topical or systemic anti-inflammatory therapy depending on the clinical situation.
The underlying cause should be addressed if a systemic disease is identified.
Treatment of Scleritis
Scleritis generally requires more active treatment.
The choice depends on:
- Severity
- Type of scleritis
- Underlying cause
- Presence of systemic disease
- Ocular complications
Treatment may include:
- Systemic nonsteroidal anti-inflammatory drugs
- Corticosteroids
- Immunomodulatory therapy
- Treatment of an underlying autoimmune disease
- Antimicrobial therapy when an infectious cause is identified
Severe or refractory cases may require treatment with systemic immunosuppressive or biologic agents under specialist supervision.
Why Treatment Differs Between Scleritis and Episcleritis
The difference can be remembered as:
Episcleritis = superficial + usually mild
Scleritis = deep + potentially destructive
Therefore, simply treating a severely painful red eye as episcleritis without proper examination can delay diagnosis of a potentially serious condition.
Complications of Episcleritis
Episcleritis usually has an excellent prognosis.
Complications are uncommon.
However, recurrent episodes may occur.
Patients with recurrent episcleritis may require evaluation for associated systemic inflammatory disease depending on their clinical history.
Complications of Scleritis
Scleritis can produce serious ocular complications.
Possible complications include:
- Scleral thinning
- Scleral necrosis
- Corneal involvement
- Peripheral ulcerative keratitis
- Uveitis
- Glaucoma
- Cataract
- Choroidal effusion
- Exudative retinal detachment
- Optic nerve involvement
- Reduced vision
- Rarely, structural perforation of the globe
The risk depends on the type and severity of scleritis.
Episcleritis vs Scleritis: Pain Is a Major Clue
A practical clinical rule is:
Episcleritis
Red eye + mild discomfort + normal vision
Scleritis
Red eye + severe deep pain ± reduced vision
However, clinical diagnosis should not rely on pain alone. A complete ocular examination is essential because several serious eye diseases can produce pain and redness.
Scleritis vs Conjunctivitis
Another important distinction is between scleritis and conjunctivitis.
| Feature | Conjunctivitis | Episcleritis | Scleritis |
|---|---|---|---|
| Pain | Mild irritation | Mild | Severe |
| Redness | Diffuse | Sectoral/diffuse | Deep/dusky |
| Discharge | Common | Usually absent | Usually absent |
| Vision | Usually normal | Usually normal | May decrease |
| Photophobia | Usually mild | Mild | More prominent |
| Tissue involved | Conjunctiva | Episclera | Sclera |
Exam clue
Significant pain + photophobia + reduced vision = investigate beyond simple conjunctivitis.
Scleritis vs Uveitis
Scleritis and anterior uveitis can both produce pain, redness, and photophobia.
However, uveitis involves the uveal tract, particularly the iris and ciliary body in anterior uveitis.
Clinical examination can reveal findings such as:
- Cells in the anterior chamber
- Flare
- Keratic precipitates
- Posterior synechiae
Scleritis primarily involves the sclera and is typically characterized by deep ocular pain and scleral inflammation.
The two conditions can also occur together.
Scleritis vs Keratitis
Keratitis primarily affects the cornea.
It may produce:
- Severe pain
- Photophobia
- Redness
- Tearing
- Reduced vision
- Corneal opacity or infiltrate
Because both keratitis and scleritis can cause severe pain, slit-lamp examination is essential for distinguishing them.
Is Scleritis an Emergency?
A suspected case of scleritis should receive prompt ophthalmic assessment, particularly when there is:
- Severe eye pain
- Reduced vision
- Significant redness
- Photophobia
- Tenderness
- Abnormal pupil findings
- Corneal involvement
- Symptoms suggesting posterior involvement
The goal is to identify the inflammation early and determine whether there is an associated systemic disease or ocular complication.
Prognosis: Episcleritis vs Scleritis
Episcleritis
The prognosis is generally excellent.
Most cases resolve without permanent damage to vision.
Scleritis
The prognosis varies.
Early diagnosis and appropriate treatment can substantially reduce the risk of complications, but severe or necrotizing forms can threaten vision and ocular integrity.
Prevention and Risk Reduction
There is no guaranteed way to prevent idiopathic episcleritis or autoimmune-associated scleritis.
However, patients with known systemic inflammatory diseases should maintain appropriate medical follow-up.
Early evaluation of:
- Persistent eye redness
- Severe ocular pain
- Recurrent inflammation
- Visual changes
can help identify serious ocular disease sooner.
Easy Mnemonic to Remember
"EPI = Easy, SCLERA = Serious"
EPIscleritis
→ Easy/mild
→ Pain usually mild
→ Inflammation superficial
SCLERITIS
→ Severe pain
→ Causes deep inflammation
→ Loss of vision possible
→ Eye may appear violaceous
→ Risk of complications
→ Inflammatory systemic disease association
→ Threat to vision
→ Immediate assessment
→ Serious disease
Frequently Asked Questions
Is episcleritis more serious than scleritis?
No. Scleritis is generally more serious because it involves deeper scleral tissue and can cause ocular complications and vision loss.
Does episcleritis cause severe pain?
Usually not. Episcleritis typically causes mild discomfort or tenderness. Severe deep pain should raise concern for scleritis or another serious ocular condition.
Can episcleritis cause vision loss?
Uncomplicated episcleritis generally does not cause significant visual loss.
Can scleritis cause blindness?
Severe untreated scleritis can cause significant ocular damage and visual loss, although the outcome depends on the type, cause, severity, and treatment.
Is scleritis associated with autoimmune disease?
Yes. Scleritis can be associated with systemic autoimmune and inflammatory disorders, including rheumatoid arthritis and systemic vasculitic diseases.
What is posterior scleritis?
Posterior scleritis is inflammation involving the posterior portion of the sclera. It may present with deep pain and visual symptoms and can be difficult to diagnose without imaging.
What is the T-sign in scleritis?
The T-sign is a characteristic B-scan ultrasonography finding caused by fluid in the Tenon's space around a thickened posterior sclera, supporting a diagnosis of posterior scleritis.
Final Takeaway
The distinction between scleritis and episcleritis is essential when evaluating a red eye.
Episcleritis is a superficial, usually mild and self-limiting inflammatory condition characterized mainly by redness and mild discomfort, with vision generally preserved.
Scleritis, on the other hand, is a deeper inflammatory disorder characterized by severe deep ocular pain, significant redness, and potentially reduced vision. It can be associated with systemic autoimmune disease and may lead to serious ocular complications.
Remember:
Episcleritis → superficial → mild → usually normal vision → good prognosis
Scleritis → deep → severe pain → possible visual loss → potentially sight-threatening
For optometry and ophthalmology students, recognizing these differences is particularly important because "red eye" is a clinical sign, not a diagnosis. A painful red eye—especially when accompanied by photophobia or reduced vision—requires careful examination to rule out potentially serious conditions.