Ophthalmology – Episcleritis

Episcleritis is an inflammatory disorder involving the episcleral tissue between the conjunctiva and sclera. It is generally mild, benign, and self-limiting, although recurrent episodes can occur. It most commonly affects young adults and women, and up to approximately 30% of patients may have an associated systemic disorder.

Two major clinical forms are recognized. Simple episcleritis causes diffuse or sectoral inflammation with intermittent episodes that usually resolve within 2–3 weeks. Nodular episcleritis produces a localized, elevated inflammatory nodule and tends to be more prolonged and painful. An underlying systemic disease is more likely in patients with nodular, severe, or recurrent disease.

The exact incidence and prevalence are unknown because many mild cases resolve without patients seeking medical attention. Important associations include collagen vascular and autoimmune diseases, particularly rheumatoid arthritis and systemic lupus erythematosus. Other associated conditions include gout, rosacea, herpes simplex, herpes zoster, and occasionally infections such as syphilis or Lyme disease. Stress and hormonal changes have also been reported as possible triggers.

Pathophysiology and Etiology

The precise pathophysiology is not completely understood. Episcleritis is thought to represent a localized inflammatory response within the superficial episcleral vascular network, sometimes triggered by systemic inflammation or infection.

Most cases are idiopathic, meaning that no specific cause can be identified. However, recurrent or severe disease should raise suspicion for an underlying systemic inflammatory, autoimmune, or infectious condition.

Diagnosis

Patients typically present with the acute onset of ocular redness, often associated with mild irritation, discomfort, and tearing. Redness may involve a localized sector of the eye or may be more diffuse. Severe deep ocular pain is unusual and should raise concern for scleritis rather than episcleritis.

Slit-lamp examination demonstrates sectoral or diffuse episcleral injection. In nodular episcleritis, a localized elevated and injected nodule is present over the sclera. The inflamed episcleral tissue can generally be moved over the underlying sclera with a cotton-tipped applicator after topical anesthesia, helping demonstrate its superficial location.

Approximately 10% of patients may have associated anterior uveitis, so examination of the anterior chamber is important.

Application of 2.5% topical phenylephrine typically causes blanching of the superficial episcleral vessels. This can help distinguish episcleritis from scleritis, in which the deeper scleral vessels generally do not blanch.

Routine laboratory investigations are unnecessary for a typical first episode. Systemic investigation should be guided by the patient’s history and review of systems. In patients with severe, recurrent, persistent, or nodular episcleritis, testing may include CBC, ESR or other inflammatory markers, ANA, rheumatoid factor, serum uric acid, and appropriate infectious testing such as syphilis studies. Additional investigations should be selected according to suspected systemic disease rather than ordered indiscriminately.

Histologically, episcleritis demonstrates nongranulomatous inflammation with vascular dilation and perivascular infiltration by lymphocytes and plasma cells.

The major differential diagnoses are scleritis, bacterial or viral conjunctivitis, and pingueculitis. Scleritis is particularly important to distinguish because it is usually more painful, involves deeper vessels, is more strongly associated with systemic autoimmune disease, and can threaten ocular integrity.

Treatment

Most episodes are self-limited and require only symptomatic treatment. Initial management consists of artificial tears and cool compresses, generally several times daily.

Patients with more significant discomfort may benefit from a short course of an oral NSAID, provided there are no contraindications. Topical anti-inflammatory therapy may occasionally be considered, but topical corticosteroids should be used cautiously and under ophthalmic supervision because prolonged or repeated use can cause elevated intraocular pressure, glaucoma, cataract formation, and increased susceptibility to infection.

More importantly, recurrent episodes associated with systemic disease require appropriate management of the underlying inflammatory or infectious condition.

Follow-up and Prognosis

Most uncomplicated episodes resolve spontaneously within a few weeks. Follow-up is particularly appropriate for patients with recurrent episodes, persistent inflammation, nodular disease, associated corneal abnormalities, anterior uveitis, or inadequate response to treatment.

The overall prognosis is very good. Episcleritis generally resolves without permanent ocular damage or visual loss. Recurrence is possible, however, and repeated episodes may warrant investigation for an underlying systemic disorder.