Scleral Diseases and Disorders: Causes, Types, Diagnosis, and Management

The sclera is the strong, white outer coat of the eye that protects the internal ocular structures, maintains the shape of the eyeball, and provides attachment for the extraocular muscles. Although the sclera is often thought of simply as the “white of the eye,” several scleral diseases and disorders can affect its structure, thickness, vascularity, and biomechanical properties.

Scleral disorders range from relatively mild conditions such as episcleritis to potentially vision-threatening diseases such as scleritis, necrotizing scleritis, scleral thinning, and posterior scleritis. Some conditions are associated with systemic autoimmune diseases, while others may result from trauma, surgery, infection, degeneration, or abnormal ocular growth.

Understanding the causes, types, symptoms, diagnosis, complications, and management of scleral diseases is important for optometry and ophthalmology students and for anyone learning about ocular pathology.

What Is the Sclera?

The sclera is the opaque, fibrous outer layer of the eyeball. It forms approximately the posterior five-sixths of the fibrous tunic of the eye, while the cornea forms the anterior one-sixth.

The sclera is mainly composed of:

• Collagen fibers
• Fibroblasts
• Elastic fibers
• Proteoglycans
• Extracellular matrix

Unlike the cornea, scleral collagen fibers are arranged irregularly. This irregular organization contributes to the sclera's characteristic white appearance.

Major functions of the sclera

The sclera:

1. Protects the internal structures of the eye
2. Maintains the shape of the eyeball
3. Provides attachment for extraocular muscles
4. Supports the posterior eye
5. Contributes to ocular biomechanics
6. Helps resist deformation caused by intraocular pressure and external forces

What Are Scleral Diseases?

Scleral diseases are conditions that affect the structure, inflammation, thickness, integrity, or function of the sclera.

They may be classified according to the underlying mechanism:

• Inflammatory disorders
• Infectious disorders
• Degenerative disorders
• Structural disorders
• Traumatic disorders
• Postsurgical disorders
• Congenital or developmental disorders
• Biomechanical disorders

The clinical presentation depends on the specific condition.

Major Types of Scleral Diseases and Disorders

Important scleral conditions include:

1. Episcleritis
2. Scleritis
3. Anterior scleritis
4. Posterior scleritis
5. Necrotizing scleritis
6. Nodular scleritis
7. Scleral thinning
8. Scleral ectasia
9. Blue sclera
10. Scleral inflammation associated with infection
11. Postsurgical scleral disorders
12. Scleral changes associated with high myopia

Let's examine each in detail.

1. Episcleritis

Episcleritis is inflammation of the episclera, the relatively superficial vascular tissue between the conjunctiva and sclera.

It is generally less severe than scleritis.

Symptoms

Patients may experience:

• Eye redness
• Mild discomfort
• Mild tenderness
• Irritation
• Watering
• Occasional photophobia

Vision is usually preserved.

Clinical appearance

The eye may show:

• Sectoral redness
• Diffuse redness
• Prominent superficial episcleral vessels

The condition is often self-limiting.

2. Scleritis

Scleritis is inflammation involving the sclera itself.

It is more serious than episcleritis because the deeper scleral tissue can become damaged.

Typical symptoms

• Severe deep eye pain
• Redness
• Tenderness
• Photophobia
• Tearing
• Blurred vision
• Pain with eye movement in some cases

Scleritis can be associated with systemic autoimmune diseases.

Scleritis Classification

Scleritis may be broadly divided into:

Anterior scleritis

Involves the anterior sclera.

Types include:

• Diffuse
• Nodular
• Necrotizing with inflammation
• Necrotizing without inflammation

Posterior scleritis

Involves the posterior portion of the sclera.

Posterior scleritis can be difficult to recognize because the external appearance may be less dramatic.

3. Anterior Scleritis

Anterior scleritis is the more visible form of scleral inflammation.

Clinical features

Patients may develop:

• Severe ocular pain
• Deep redness
• Tenderness
• Photophobia
• Tearing
• Blurred vision

The sclera may appear deep red or violaceous.

In severe cases, inflammation can cause scleral thinning and tissue destruction.

4. Posterior Scleritis

Posterior scleritis occurs behind the equator of the eyeball.

Because the posterior sclera cannot be directly visualized easily, diagnosis may require imaging.

Symptoms

• Deep eye pain
• Headache
• Reduced vision
• Pain with eye movement
• Photophobia

Possible associated findings include:

• Choroidal effusion
• Exudative retinal detachment
• Optic disc swelling
• Thickening of the posterior eye wall

T-Sign in Posterior Scleritis

One of the important imaging findings in posterior scleritis is the T-sign on B-scan ultrasonography.

It results from fluid accumulating in the Tenon's space around the posterior sclera.

The ultrasound may show:

Thickened posterior sclera + fluid in Tenon's space → T-sign

Exam point

T-sign = classic B-scan finding in posterior scleritis.

5. Necrotizing Scleritis

Necrotizing scleritis is a severe form of scleral inflammation.

It can cause:

• Scleral tissue destruction
• Severe pain
• Progressive thinning
• Areas of necrosis
• Risk of perforation
• Significant visual complications

Necrotizing scleritis is particularly important because it may indicate significant underlying systemic inflammatory or vasculitic disease.

6. Nodular Scleritis

In nodular scleritis, a localized inflammatory nodule develops within the sclera.

It may present as:

• Localized red area
• Raised scleral lesion
• Significant tenderness
• Deep ocular pain

Nodular scleritis can sometimes resemble other localized ocular lesions, making clinical examination important.

7. Scleral Thinning

Scleral thinning occurs when the scleral tissue becomes abnormally thin.

It can result from:

• Severe inflammation
• Trauma
• Previous ocular surgery
• Degenerative conditions
• High myopia
• Certain systemic connective tissue disorders

Severe thinning can compromise the structural integrity of the eyeball.

Blue Sclera

Blue sclera occurs when the sclera becomes sufficiently thin that underlying pigmented tissues become visible.

Instead of the sclera actually producing blue pigment, the appearance results from light transmission through a thinned scleral coat.

It may be associated with certain inherited connective tissue and skeletal disorders.

Exam point

Blue sclera → think scleral thinning with increased visibility of underlying tissue.

8. Scleral Ectasia

Scleral ectasia refers to abnormal thinning and outward expansion of the sclera.

It may occur locally or over a larger area.

Possible associations include:

• High myopia
• Trauma
• Previous surgery
• Inflammatory disease
• Structural abnormalities

Scleral ectasia can change the shape of the globe and may affect visual function.

9. Infectious Scleral Disease

Although many scleral inflammatory disorders are noninfectious, infectious scleritis can occur.

Potential infectious causes include:

• Bacterial infection
• Herpes zoster
• Syphilis
• Tuberculosis
• Fungal infection in selected cases

Infectious scleritis requires careful evaluation because treatment differs substantially from autoimmune or noninfectious scleritis.

10. Postsurgical Scleral Disorders

Scleral inflammation or thinning can occasionally occur following ocular surgery.

Possible contributing factors include:

• Surgical trauma
• Local inflammation
• Infection
• Tissue ischemia
• Delayed inflammatory responses

A history of previous ocular surgery is therefore important when evaluating unexplained scleral abnormalities.

11. Scleral Changes in High Myopia

The sclera plays an important role in the development and progression of axial myopia.

In progressive myopia, the eye becomes elongated.

This is associated with changes in:

• Collagen organization
• Extracellular matrix
• Scleral remodeling
• Biomechanical properties

As the sclera becomes more susceptible to expansion, the posterior segment can elongate.

This contributes to the structural changes seen in high and pathological myopia.

Causes of Scleral Diseases

The causes of scleral disorders vary depending on the specific disease.

Autoimmune causes

Important systemic associations include:

• Rheumatoid arthritis
• Granulomatosis with polyangiitis
• Systemic lupus erythematosus
• Relapsing polychondritis
• Polyarteritis nodosa
• Inflammatory bowel disease
• Other systemic vasculitic disorders

Infectious Causes

Possible infectious causes include:

• Bacterial infection
• Viral infection
• Herpes zoster
• Syphilis
• Tuberculosis
• Fungal infection

An infectious cause should be considered particularly when there are risk factors, atypical features, or poor response to conventional anti-inflammatory therapy.

Traumatic Causes

Trauma may damage the sclera directly.

Examples include:

• Blunt trauma
• Penetrating trauma
• Foreign-body injury
• Surgical trauma

Severe trauma may result in scleral rupture or laceration, which is an ocular emergency.

Degenerative Causes

Degenerative changes can weaken the sclera.

They may be associated with:

• Age-related changes
• High myopia
• Previous inflammation
• Local tissue degeneration

Systemic Diseases Associated With Scleral Disorders

Scleral inflammation can sometimes be the first indication of an underlying systemic inflammatory disease.

Important associations include:

Rheumatoid arthritis

One of the classic systemic diseases associated with scleritis.

Systemic vasculitis

Conditions affecting blood vessels can cause severe inflammatory scleral disease.

Relapsing polychondritis

May be associated with ocular inflammation including scleritis.

Inflammatory bowel disease

Both Crohn disease and ulcerative colitis can have ocular manifestations.

Systemic lupus erythematosus

Ocular inflammatory manifestations can occur.

Symptoms of Scleral Disease

Symptoms depend on the underlying disorder.

Common symptoms include:

• Red eye
• Deep eye pain
• Tenderness
• Photophobia
• Watering
• Blurred vision
• Pain with eye movement
• Localized swelling
• Changes in scleral color
• Visible thinning
• Decreased vision

Important warning sign

Severe eye pain associated with redness should not be assumed to be simple conjunctivitis.

Clinical Signs of Scleral Disease

A clinician may observe:

• Deep scleral redness
• Violaceous discoloration
• Dilated episcleral vessels
• Scleral nodules
• Scleral thinning
• Areas of necrosis
• Tenderness
• Associated corneal inflammation
• Uveitis
• Choroidal abnormalities

The presence of associated intraocular inflammation may indicate a more severe disease process.

Diagnosis of Scleral Diseases

Diagnosis begins with a detailed history and ocular examination.

Important components include:

1. Visual acuity

Any reduction in visual acuity is clinically significant.

2. Slit-lamp examination

The clinician evaluates:

• Conjunctiva
• Episclera
• Sclera
• Cornea
• Anterior chamber
• Iris

3. Assessment of pain

The severity and character of pain help differentiate superficial from deeper inflammation.

4. Ocular motility

Pain with movement can occur in several inflammatory ocular conditions and should be assessed.

5. Fundus examination

Useful when posterior involvement or visual loss is present.

Imaging for Scleral Disease

Imaging can be especially useful in posterior disease.

B-scan ultrasonography

Particularly useful for suspected posterior scleritis.

It can demonstrate:

• Posterior scleral thickening
• Fluid around the posterior globe
• Choroidal abnormalities
• Exudative retinal detachment

The T-sign is an important finding.

Optical Coherence Tomography

OCT may help evaluate associated retinal, choroidal, and optic nerve abnormalities.

It can be useful when scleral disease produces secondary changes in posterior ocular structures.

Laboratory Investigations

Laboratory investigations are selected according to the clinical presentation.

Possible tests include:

• CBC
• ESR
• CRP
• Rheumatoid factor
• Anti-CCP antibodies
• ANA
• ANCA
• Syphilis testing
• Tuberculosis testing
• Other targeted autoimmune or infectious investigations

The goal is to identify an underlying systemic or infectious cause when appropriate.

Differential Diagnosis of a Red Eye

Scleral disease should be differentiated from other causes of ocular redness.

Important differential diagnoses include:

• Conjunctivitis
• Episcleritis
• Keratitis
• Anterior uveitis
• Acute angle-closure glaucoma
• Corneal ulcer
• Ocular trauma

Clinical principle

Redness + severe pain + photophobia or reduced vision = requires careful ocular assessment.

Scleritis vs Episcleritis

This is one of the most important distinctions in scleral disease.

Feature | Episcleritis | Scleritis

• Inflammation: Superficial | Deep
• Pain: Mild | Severe
• Redness: Bright red/pink | Deep red/violaceous
• Vision: Usually normal | May be reduced
• Systemic disease: Sometimes associated | Important association
• Complications: Uncommon | Potentially serious
• Treatment: Often supportive | Usually requires systemic therapy

Easy memory trick

EPI = Easy

SCLERITIS = Serious

Management of Episcleritis

Most cases are self-limiting.

Management may include:

• Observation
• Reassurance
• Artificial tears
• Cold compresses
• Anti-inflammatory treatment when clinically indicated

If recurrent or associated with systemic symptoms, further evaluation may be considered.

Management of Scleritis

Scleritis generally requires more aggressive treatment.

Treatment depends on whether the disease is:

• Autoimmune
• Infectious
• Idiopathic
• Associated with another systemic disorder

Possible treatments include:

Systemic NSAIDs

May be used for appropriate cases of noninfectious scleritis.

Corticosteroids

Systemic corticosteroids may be necessary in more severe inflammatory disease.

Immunomodulatory therapy

Patients with severe, recurrent, necrotizing, or steroid-dependent disease may require immunomodulatory treatment under specialist supervision.

Treatment of underlying disease

If an autoimmune disease is identified, appropriate systemic management is essential.

Antimicrobial therapy

If infection is responsible, antimicrobial therapy directed at the identified pathogen is required.

Management of Scleral Thinning

Management depends on the cause and severity.

The underlying inflammatory, infectious, traumatic, or degenerative process must be addressed.

Severe structural weakness may require surgical intervention in selected cases.

Scleral Buckling

The sclera also plays an important role in retinal surgery.

In selected cases of rhegmatogenous retinal detachment, a scleral buckle can be placed around the eye.

The buckle indents the sclera and helps reduce vitreoretinal traction around retinal breaks.

This is a good example of how understanding scleral anatomy has direct surgical significance.

Scleral Contact Lenses

Scleral contact lenses are large-diameter lenses that rest primarily on the ocular surface overlying the sclera.

They create a fluid reservoir over the cornea.

They may be useful for selected patients with:

• Keratoconus
• Irregular corneal surfaces
• Corneal ectasia
• Ocular surface disorders
• Significant corneal irregularity

The sclera therefore has an important role not only in pathology but also in modern contact lens practice.

Complications of Scleral Diseases

Complications depend on the specific disease.

Potential complications include:

• Scleral thinning
• Scleral necrosis
• Corneal involvement
• Peripheral ulcerative keratitis
• Uveitis
• Glaucoma
• Cataract
• Choroidal effusion
• Exudative retinal detachment
• Optic nerve involvement
• Vision loss
• Globe perforation in severe destructive disease

When Should a Patient Seek Urgent Eye Care?

A patient with a red eye should receive prompt professional evaluation when symptoms include:

• Severe eye pain
• Sudden reduction in vision
• Significant photophobia
• Marked tenderness
• Abnormal pupil
• Corneal opacity
• Trauma
• Severe headache with eye symptoms
• Persistent or worsening redness

These symptoms may indicate scleritis or another serious ocular disorder.

Scleral Disease and Optometry

Optometrists can play an important role in the recognition of scleral disease.

During a routine eye examination, the clinician may identify:

• Unusual scleral redness
• Localized scleral lesions
• Scleral thinning
• Deep ocular tenderness
• Associated corneal findings
• Changes suggesting systemic inflammatory disease

Recognizing suspicious findings and promptly referring the patient for ophthalmic assessment can help prevent complications.

Scleral Diseases and Systemic Health

One of the most important concepts in scleral pathology is that the eye can sometimes provide clues to systemic disease.

A patient presenting with scleritis may have an underlying inflammatory or autoimmune condition.

Therefore, the evaluation should not always stop at the eye.

A thorough medical history should consider:

• Joint symptoms
• Skin changes
• Respiratory symptoms
• Gastrointestinal symptoms
• Previous autoimmune disease
• Previous infections
• Recent surgery
• Trauma

Frequently Asked Questions About Scleral Diseases

What is the most common scleral disease?

Episcleritis and scleritis are among the important inflammatory disorders involving the scleral region. Their clinical significance differs considerably.

What is the difference between scleritis and episcleritis?

Episcleritis is superficial and usually mild, while scleritis involves deeper scleral tissue and is often significantly painful and potentially vision-threatening.

Is scleritis dangerous?

Yes. Scleritis can cause serious ocular complications and vision loss, particularly severe or necrotizing forms.

What autoimmune disease is commonly associated with scleritis?

Rheumatoid arthritis is a classic systemic association.

What causes blue sclera?

Blue sclera is generally related to scleral thinning, which allows underlying tissues to become more visible.

What is posterior scleritis?

Posterior scleritis is inflammation of the posterior sclera and may cause deep eye pain, visual disturbance, choroidal changes, or exudative retinal detachment.

What is the T-sign?

The T-sign on B-scan ultrasonography is a classic imaging finding associated with posterior scleritis.

Can scleral disease cause vision loss?

Yes. Severe scleral inflammation can affect adjacent ocular structures and lead to visual impairment.

Conclusion

Scleral diseases and disorders encompass a broad range of inflammatory, infectious, structural, degenerative, traumatic, and biomechanical conditions. Among them, episcleritis and scleritis are particularly important because they can both present as a red eye but have very different clinical implications.

Episcleritis is generally superficial and self-limiting, whereas scleritis is a deeper inflammatory condition that can cause severe pain, scleral destruction, and vision-threatening complications. Posterior scleritis may be particularly challenging to recognize and often requires imaging such as B-scan ultrasonography.

Scleral thinning, ectasia, blue sclera, high-myopia-related scleral remodeling, and postsurgical changes further demonstrate the importance of the sclera in ocular health.

The key clinical message is:

Red eye + severe deep pain ± reduced vision → think beyond conjunctivitis and evaluate for serious ocular disease, including scleritis.

Understanding the anatomy, causes, classification, clinical features, diagnosis, treatment, and complications of scleral disorders provides an essential foundation for students and clinicians in optometry and ophthalmology.