What is scleritis and its types?

Scleritis is inflammation of the sclera or ‘white of the eye’ and manifests with eye pain and redness. It is associated with various pathologies and infections, and if it is not detected and treated in time, it can cause blindness.

Scleritis is inflammation of the sclera, or sclera, a white, thick membrane that constitutes the outermost part of the eyeball, although anteriorly is covered by the conjunctiva. This visible anterior part is what is called the ‘white of the eye.’ The next layer immediately inside the sclera is the choroid. The sclera shapes the eye and protects it, is hard and resistant. In front, it joins the cornea through the sclerocorneal limbus.

Inflammation of the sclera usually occurs in systemic autoimmune or inflammatory diseases or infectious processes. Scleritis hurts and can lead to blindness if not diagnosed and treated early. Most of the time, scleritis affects the front part of the eye, so there is intense redness in addition to eye pain.

Scleritis should not be confused with episcleritis. The episclera is the sclera’s outermost membrane and allows ocular mobility and gliding with neighboring orbital structures. Its inflammation is relatively frequent but, unlike scleritis, it is usually a benign process that subsides on its own in a couple of weeks. In any case, if there are pain and redness in the eye, consult an ophthalmologist.

Types of scleritis

There are different types of scleritis depending on the affected part:

  • Anterior scleritis: accounts for 90% of cases. In turn, it is divided into diffuse anterior scleritis, nodular anterior scleritis, and necrotizing anterior scleritis, which is the rarest form but also the most dangerous.
  • Posterior scleritis: in this type, there is inflammation of the insertion of the lateral and medial muscles of the eye. The subtypes are more difficult to distinguish, so it is often treated as the most severe form.

Fortunately, scleritis is not very common. It mainly affects people in the middle ages of life, which is when the diseases to which it is associated appear most. Scleritis associated with rheumatological diseases is more common in women and is often bilateral, affecting both eyes. Those infectious causes are more frequent in men and can be unilateral.

Scleritis always requires an ophthalmologist’s urgent evaluation to establish the diagnosis and carry out adequate treatment to avoid long-term sequelae. Also, an assessment of other possible symptoms should be carried out because this ocular inflammation may be the first manifestation of a generalized disease that would require the collaboration of other specialists.

Causes of scleritis

The scleritis in most patients suffering associated with inflammatory phenomena and autoimmune, especially vasculitic type, although the sclera itself is an avascular structure (without blood vessels) and receives its nutrients by diffusion from the episclera and the choroid, which does have abundant vascularization. Inflammatory cells and immune complex deposits appear in the sclera.

It is not known why in patients with autoimmune diseases who suffer from scleritis, the eye is affected by inflammation. It seems that local trauma to the eye can favor the appearance of scleritis. Another cause of slaying that can trigger scleritis is ocular surgery, with the highest risk in people with a systemic autoimmune disease or underlying.

In approximately half of the cases, scleritis is associated with a systemic autoimmune or autoinflammatory disease. On other occasions, scleritis may appear in the context of systemic infectious processes. Other diseases in which symptoms of various organs can appear, including scleritis, are inflammatory bowel disease and sarcoidosis.

Connective tissue diseases in which scleritis can occur are rheumatoid arthritis, reactive arthritis, systemic lupus erythematosus, and relapsing polychondritis. Vasculitic-type diseases in which scleritis can be one of its manifestations are Wegener’s disease, microscopic polyangiitis, Churg-Strauss syndrome, polyarteritis nodosa, Cogan’s syndrome, Behçet’s syndrome, and urticarial vasculitis.

There are also infections in which there may be ocular manifestations in the form of scleritis. Examples of these infections are syphilis, tuberculosis, Lyme disease, or shingles: all can cause infectious-type scleritis. Fungal infection caused by the Aspergillus fungus is a rare but serious cause of scleritis. The human immunodeficiency virus (HIV) can also cause scleritis.