What Is Scleritis

Overview

The sclera, known as the white part of the eye, serves as a protective outer layer and comprises approximately 83% of the eye's surface. It is connected to muscles that facilitate eye movement. 

Scleritis is a condition characterised by significant inflammation and redness of the sclera. It can cause intense pain and is believed to occur due to an exaggerated immune system response. The specific type of scleritis experienced depends on the location of the inflammation. Although most individuals with scleritis experience severe pain, there are occasional exceptions. 

Timely treatment involving medication is essential to prevent the progression of scleritis. If left untreated, severe cases can result in partial or complete vision loss. 

Types of scleritis

Doctors utilise the Watson and Hayreh classification to differentiate between the various types of scleritis.¹ This classification system is based on whether the disease affects the front (anterior) or back (posterior) of the sclera. The anterior forms of scleritis are more likely to be associated with an underlying illness. 

The subtypes of anterior scleritis are as follows:²

1. Anterior scleritis: This is the most common type of scleritis
2. Nodular anterior scleritis: This is the second most common form
3. Necrotizing anterior scleritis with inflammation: This is the most severe form of anterior scleritis
4. Necrotizing anterior scleritis without inflammation: This is the rarest form of anterior scleritis

On the other hand, posterior scleritis is more challenging to diagnose and detect because its symptoms can vary and resemble those of other disorders.³ 

Causes of scleritis

There are hypotheses suggesting that T cells, a type of immune cells, play a role in the development of scleritis.⁴ The immune system is a complex network comprising organs, tissues, and circulating cells that collaborate to protect the body against bacterial and viral infections. T cells specifically function to eliminate invading pathogens, which are organisms capable of causing diseases. In the case of scleritis, it is believed that T cells start targeting the scleral cells of the eye. However, the precise reasons behind this occurrence are still unknown to doctors.

Signs and symptoms of scleritis

If left untreated, each type of scleritis can lead to worsening symptoms. The primary symptom of scleritis is severe eye pain that does not respond well to painkillers. The pain intensifies with eye movements and may extend to the entire face, particularly on the side of the affected eye. 

Additional symptoms can include: 

1. Excessive tearing (lacrimation)
2. Decreased vision
3. Blurry vision
4. Sensitivity to light (photophobia)
5. Redness of the sclera (the white part of the eye)

Posterior scleritis, however, does not cause as severe pain as other types, making its symptoms less noticeable. Symptoms of posterior scleritis include: 

1. Deep-seated headaches
2. Pain worsened by eye movement
3. Eye irritation
4. Double vision

Some individuals may experience minimal or no pain from scleritis. This could be due to: 

1. Having a milder case of the condition
2. Scleromalacia perforans, which is a rare complication of advanced rheumatoid arthritis (RA)
3. A history of using immunosuppressive medications (which inhibit immune system activity) prior to the onset of symptoms

Management and treatment for scleritis

The primary goal in treating scleritis is to address the inflammation and prevent permanent damage. Since pain in scleritis is closely associated with inflammation, reducing swelling is key to alleviating symptoms. 

Treatment for scleritis typically follows a step-by-step approach, where subsequent medications are employed if initial options prove ineffective. 

The medications utilised for treating scleritis include:⁵

1. Nonsteroidal anti-inflammatory drugs (NSAIDs): These are commonly used for nodular anterior scleritis as they help reduce inflammation and alleviate pain
2. Corticosteroid pills (e.g., prednisone): If NSAIDs fail to control inflammation, oral corticosteroids may be prescribed
3. Oral glucocorticoids: These are the preferred choice for treating posterior scleritis
4. Immunosuppressive drugs combined with oral glucocorticoids: This combination is preferred for the most severe form of scleritis, necrotizing scleritis
5. Antibiotics: They may be prescribed to prevent or treat scleral infections
6. Antifungal medications: These are commonly used for infections associated with Sjogren's syndrome⁶ 
7. In severe cases, surgery may be necessary to repair scleral tissues, improve muscle function, and prevent vision loss

Additionally, treating the underlying causes of scleritis is crucial. For instance, effectively managing an autoimmune disorder can help prevent recurrent episodes of scleritis.

Diagnosis of scleritis

To diagnose scleritis, your doctor will conduct a thorough examination, review your medical history, and may order laboratory evaluations.⁷ 

During the diagnostic process, your doctor may inquire about systemic conditions you have experienced, such as rheumatoid arthritis (RA), Wegener's granulomatosis, or inflammatory bowel disease (IBD). They may also ask about any history of eye trauma or surgery. 

To assist in making a diagnosis, your doctor may employ the following tests:

• Ultrasonography: This imaging technique helps examine changes occurring in or around the sclera
• Complete blood count: This test assesses signs of infection and immune system activity
• Scleral biopsy: In this procedure, a sample of scleral tissue is removed for microscopic examination

Risk factors

Scleritis can manifest at any age, with a slightly higher incidence in women compared to men. However, there is no specific racial or geographical predisposition associated with this condition.⁸ 

Certain factors increase the likelihood of developing scleritis, including:

• Wegener's disease (Wegener's granulomatosis): This uncommon disorder involves inflammation of the blood vessels
• Rheumatoid arthritis (RA): An autoimmune disorder characterised by joint inflammation
• Inflammatory bowel disease (IBD): Inflammation of the bowel leading to digestive symptoms
• Sjogren's syndrome: An immune disorder that causes dry eyes and mouth
• Lupus: An immune disorder resulting in skin inflammation
• Eye infections (which may or may not be linked to autoimmune diseases)
• Eye tissue damage due to accidents

FAQs

Can scleritis be prevented?

Scleritis cannot be prevented especially if it is caused by an autoimmune disease, however early treatment interventions can prevent it from progressing. 

How common is scleritis?

Scleritis is a rare condition that affects around 4 in 100,000 every year in the UK. Majority of patients are in the middle age group, with ages ranging from 40 to 60 years. Females are slightly more prone to develop scleritis. 

When should I see a doctor?

If you are experiencing severe eye pain that does not respond to medication, excessive tearing, reduced or blurry vision and redness, get in touch with your GP, or doctor. 

Summary

The sclera is the protective outer layer of the eye and makes up about 83% of its surface. It can be affected by a condition called scleritis, which is characterised by inflammation and redness of the sclera. Scleritis can cause intense pain and is believed to be caused by an overactive immune response. Timely treatment is crucial to prevent vision loss, and medication is typically used to reduce inflammation. Scleritis can be classified into different types based on the location of inflammation, and it can be associated with underlying illnesses such as autoimmune disorders or infections.