The sclera is an incomplete shell comprising approximately 90% of the outer coat of the eye; it begins at the limbus and terminates at the optic canal. The sclera is composed of extracellular matrix—collagen, elastin, proteoglycans, the bundles of which run in whorls and loops. The innermost part of the sclera is the lamina fusca, which has many grooves caused by the passage of ciliary vessels and nerves. Anteriorly, the sclera is continuous with the cornea at the corneoscleral junction, and lying just posterior to this, within the sclera, is the canal of Schlemm. Posterior to the canal is the scleral spur, which is triangular with its apex pointing anteriorly and inward and attaching to the ciliary body. The posterior pole of the sclera is weakened and has a sieve-like appearance (lamina cribrosa) where it is perforated by the axons of the optic nerve. Here, the sclera is fused with the dura mater and arachnoid sheaths of the optic nerve.
Scleritis is defined as inflammation of the sclera, and it has a characteristic clinical picture. It is typically a severe painful inflammatory process centered in the sclera that may involve the cornea, adjacent episclera, and underlying uvea; it poses a significant threat to vision.Types may include:Anterior scleritis.
- Anular scleritis.
- Brawny scleritis.
- Deep scleritis.
- Gelatinous scleritis.
- Malignant scleritis.
- Necrotizing scleritis.
- Nodular scleritis.
- Posterior scleritis.
Inflammation of the sclera is usually associated with infections, chemical injuries, or autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus. Sometimes the cause is unknown.
Infectious scleritis can be viral, bacterial, fungal, and parasitic. It is uncommon particularly in the absence of infectious keratitis. The mechanism of inflammation in many infections is thought to be partly or wholly immune mediated. Many organisms have been reported as possible causes of scleritis. Infections occur in tissue compromised by disease or trauma—both iatrogenic and accidental.A common risk factor for infectious scleritis is a history of pterygium surgery with adjunctive mitomycin-C administration or beta irradiation.Other risk factors may include:Wegener's granulomatosis.
- Systemic lupus erythematosus (SLE).
- Polyarteritis nodosa.
- Takayasu's arteritis
Patients with scleritis may present in one of two ways—they may already be known to have an underlying related disorder, such as rheumatoid arthritis, or the scleritis may present de novo in the absence of any known underlying systemic disease. The characteristic feature of scleritis is the severe pain that may involve the eye and orbit and radiates to involve the ear, scalp, face, and jaw. Scleritic pain is typically dull and boring in nature, exacerbated by eye movement, is worse at night often interfering with sleep, and characteristically wakens the patient from sleep early in the morning.Symptoms:Eye pain that is severe.
- Red patches on the normally white part of the eye.
- Blurred vision.
- Sensitivity to light - very painful.
- Tearing of the eye.
- Decreased visual acuity.
Your eye doctor will ask you about your medical history and conduct a thorough examination.Scleritis is best detected by examining the sclera in daylight; retracting the lids helps determine the extent of involvement.Because of the association between scleritis and other general medical conditions, your doctor may suggest a comprehensive medical examination, including blood counts and other tests and evaluations.
Other aspects of the eye exam i.e. visual acuity testing, slit lamp examination, etc may be helpful. Ancillary tests CT scans, MRIs, and ultrasonographies may also be helpful.Treatment:If scleritis is caused by an underlying disease, treatment of that disease may be necessary.
- Corticosteroid eye drops help reduce the inflammation. Sometimes corticosteroids pills are taken by mouth. Newer, non-steroid anti-inflammatory (NSAID) drugs may be used in some cases.
- If infection is the cause, your treatment will include antibiotics. In severe cases, surgery may be required to repair injured areas of the eyeball.
- Patients with autoimmune diseases such as rheumatoid arthritis may need careful monitoring by an ophthalmologist with experience treating ocular inflammatory diseases.
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