Scleritis is an inflammation or swelling of the surface membrane covering the sclera. Anterior and posterior scleritis form the two types of scleritis.

Scleritis is associated with autoimmune diseases such as lupus which is a chronic inflammatory disease that occurs when the immune system attacks its own tissues and organs, inflammatory bowel disease, certain connective tissue diseases like cellulitis, eye infection, and among other diseases. Some cases of scleritis involve undetermined causes.

The exact pathophysiology of scleritis is still not fully understood. Researchers believe that inflammatory cells, especially T cells and macrophages have an important role in the inflammatory process leading to scleritis.

Scleritis is more prevalent in people aged 30 to 60 and in women. Redness, pain and tenderness in the eye, sensitivity to light, tearing of the eye, and blurred vision are some symptoms of scleritis.

Tests that may be used to diagnose scleritis are physical exam including an eye test that uses slit lamp examination, lab tests such as complete blood count (CBC),  and erythrocyte sedimentation rate to look for other conditions that may be causing the problem , and imaging studies such as B-scan ultrasonography.

The type of scleritis determines treatment type that could be corticosteroid eye drops, corticosteroid pills, nonsteroid anti-inflammatory (NSAID) drugs, and among other treatments. Treating an underlying cause is essential in controlling scleritis symptoms.

Retinal detachment; disposition of the retina, a thin layer of tissue located at the back of the eye, and rapid permanent visual loss are some of the complications for scleritis when no treatment is provided.

Prevention for the majority of scleritis is not possible, but some cases of autoimmune diseases could be managed via regular check-ups with prior knowledge about the case by doctors.

With treatment, the majority of cases are resolved. Sometimes, recurring scleritis is possible and could lead to serious issues like vision loss with no treatment.

According to a study published in the Rheumatic Disease Clinics of North America journal, the prevalence of scleritis in the general population is estimated to be six cases per 100,000 people.

Scleritis is an inflammation in the white outer wall of the eye.

There are two types of scleritis, include:

• Anterior scleritis

Anterior scleritis, the most common type of scleritis, that affects the front portion of the sclera; and is divided into three types: 

• Diffuse scleritis

It is the most common type of anterior sclera that is very treatable and is with redness and inflammation that affects the whole or part of the front portion of the sclera. 

• Nodular scleritis

It is when nodules or bumps are present on the surface of the eye. 

• Necrotizing scleritis

The most severe form of anterior scleritis, that can cause severe damage to the scleral tissue and even eye loss It is characterized by extreme pain, and tenderness. The two types of necrotizing scleritis are necrotizing scleritis with corneal inflammation, and necrotizing scleritis without inflammation (scleromalacia perforans). 

• Posterior scleritis

As the name suggests, this type affects the back of the eye and is often not related to an underlying systemic disorder. This form is the most rare form and It is difficult to diagnose. It can be present with severe eye pain, retinal detachment, loss of vision and folds in the vascular layer of the eye known as choroidal folds. Posterior scleritis can occur separately or with anterior scleritis. 

Sometimes, causes of scleritis is unknown. Scleritis may linked with autoimmune diseases, such as:

• Different forms of inflammatory arthritis; a group of diseases characterized by inflammation of the joints and often other tissues. 
• Eye infection.
• Lupus.
• Certain connective tissue diseases like cellulitis.
• Inflammatory bowel disease.
• Sjogren's syndrome; disorder of the immune system that causes dry eyes and mouth.
• Wegener's granulomatosis; rare autoimmune disease.
• Scleroderma; group of rare diseases involving the hardening and tightening of the skin and connective tissues.

Trauma of the eye and rarely a fungus or a parasite could be responsible for scleritis. 

There are many factors that can increase the risk of scleritis, including:

• Age

Scleritis occurs most often in people between the ages of 30 and 60. 

• Gender

Women are more commonly affected than men. 

• Autoimmune disease

The presence of systemic inflammatory diseases can increase the risk of scleritis, such as rheumatoid arthritis. 

Researchers believe that inflammatory cells; composed of five types of cells that play a role in the inflammatory response to a foreign substance. Especially T cells and macrophages that have an important role in the inflammatory process that leads to scleritis. Some studies have found evidence of inflammation of the blood vessels, with neutrophil invasion and death of vessel wall tissue. Antibody deposition has also been observed. Despite this, the exact pathophysiology of scleritis is still not fully determined. 

Symptoms of scleritis include:

• Redness.
• Pain and tenderness in the eye.
• Sensitivity to light.
• Tearing of the eye. 
• Blurred vision.
• Red patches on the normally white part of the eye. 
• Moderate or severe pain, which is exacerbated by eye movement.
• Sleep disturbances.
• Vision loss. 

 A rare form of this disease can be have no eye pain or redness. 

Tests and exams that used to diagnosis scleriits, including:

• Physical exam

Physical exam using natural light is useful in differentiating the subtle color differences between scleritis and episcleritis. Using slit-lamp biomicroscopy, inflamed scleral vessels often have a criss-crossed pattern and are adherent to the sclera. 

• Laboratory tests

Lab tests include complete blood count (CBC), erythrocyte sedimentation rate

(ESR) or C-reactive protein (CRP), antinuclear antibodies, anti-DNA antibodies, rheumatoid factor, antineutrophil cytoplasmic antibodies, urinalysis, syphilis serology, serum uric acid and sarcoidosis screening, these lab tests may help detect other conditions that maybe causing sclerites. 

• Imaging studies

Posterior sclerites detection may use B-scan ultrasonography and orbital magnetic resonance imaging (MRI). 

Scleritis is a serious condition that can lead to loss of vision if untreated. Treatment varies depending on the type of scleritis . Treatment methods include: 

• Corticosteroid eye drops to help reduce the inflammation.
• Corticosteroid pills.
• Newer, nonsteroid anti-inflammatory (NSAID) drugs.
• Certain anti-cancer drugs (immune-suppressants) for severe cases. 
• Surgery, in more severe cases to repair scleral tissues and prevent further loss of vision. 

An underlying disease that might be causing sclertits and therefore needs to be treated. Even with treatment, sclertitis has a possibility to recur.  

Complications may include:

• Retinal detachment.
• Angle-closure glaucoma; where the iris of the eye becomes so close to the drainage angle of the eye, leading to its block and raising eye pressure.
• Rapid permanent visual loss. 
• Recurrent scleritis or other inflammatory diseases such as peripheral keratitis, uveitis, cataract and glaucoma. 
• Posterior scleritis is accompanied by inflammation of the vitreous body and exudative detachments; type of retinal detachment. 
• Side effects of long-term corticosteroid therapy.
• Perforation of the eyeball, leading to vision loss if the condition is left untreated. 

An ophthalmologist should be regularly visited in the case of people with autoimmune diseases, or those with prior medical history of such diseases. Most cases of scleritis cannot be prevented. 

Although treatment resolves the issue in most cases, the condition could recur. Untreated scleritis could lead to vision loss.

Disorders, particularly serious ones, could cause sclertitis but may go undetected when first encountering the disease. The outcome will depend on the specific disorder. 

According to a study published in the Rheumatic Disease Clinics of North America journal, the prevalence of scleritis in the general population is estimated to be six cases per 100,000 people, but has been described in between 0.2% and 6.3% for patients with rheumatoid arthritis and up to 7% of those with what is called Wegener’s granulomatosis.