Episcleritis (inflammation of the episcleral tissue between the conjunctiva and the sclera) should be distinguished from scleritis (inflammation of the sclera) and from iritis and conjunctivitis.
Episcleritis is more common than usual in patients with connective tissue diseases.
Episcleritis usually resolves on its own in 1-2 weeks even without treatment.
Aetiology and pathology
Episcleritis is rare because blood vessels are sparse in the sclera and the conjunctiva protects it from external irritants. The inflammation is nearly always endogenous, and scleral diseases resemble connective tissue diseases.
The outer, vascular, and loose layer of sclera is called episclera. Episcleritis is more common than scleritis (picture 1).
Scleritis is a rare and severe vision-threatening vasculitis-induced disease where the choroideal blood vessels become destroyed.
Episcleritis may be a symptom of a connective tissue disease or it may be associated with allergies.
Symptoms and signs
The patient is asymptomatic, or has mild ocular pain. The eye may feel unpleasant. Typical symptoms also include local redness and mild tenderness to pressure.
The distribution of episcleritis can be nodular, sectorial or diffuse. In nodular inflammation a red node appears under the conjunctiva, in sectorial episcleritis the erythema spreads sectorially to the corneal margin, and in the diffuse form the episclera is erythematous around the cornea (picture 2).
In episcleritis, lilac-coloured blood vessels are visible on the sclera. The vessels do not move when the conjunctiva is moved with a cotton swab stick after applying local anaesthesic eye drops: this feature helps in differentiating the condition from conjunctivitis where the enlarged vessels move together with the conjunctiva.
Mild iritis associated with diffuse episcleritis may cause differential diagnostic problems. Consider iritis as the diagnosis if the eye is sensitive to light or if visual acuity is impaired.
In episcleritis, there is no discharge from the eye. Eye movements may possibly be painful because the inflammation may be located at the insertion of an extraocular muscle.
Episcleritis is cured without sequelae, but scleritis results in a scleral scar that can be seen as bluish atrophy of the sclera under the conjunctiva.
Treatment
Good spontaneous healing tendency
Episcleritis is treated with oral non-steroidal anti-inflammatory (NSAID) drugs. Local NSAID drops can also be used.
The patient should avoid draught and heat, which delay healing.
Patients with prolonged inflammation should be referred to an ophthalmologist for consideration of glucocorticoid treatment.
It is advisable to refer the patient to an ophthalmologist also if the episcleritis recurs frequently.
Scleritis always requires treatment by an ophthalmologist.
References
Salama A, Elsheikh A, Alweis R. Is this a worrisome red eye? Episcleritis in the primary care setting. J Community Hosp Intern Med Perspect 2018;8(1):46-48. [PubMed]
Daniel Diaz J, Sobol EK, Gritz DC. Treatment and management of scleral disorders. Surv Ophthalmol 2016;61(6):702-717. [PubMed]
Sainz de la Maza M, Molina N, Gonzalez-Gonzalez LA, et al. Clinical characteristics of a large cohort of patients with scleritis and episcleritis. Ophthalmology 2012;119(1):43-50. [PubMed]