Episcleritis is a fairly common cause of a transient red eye, typically occurring in young to middle age adults. Patients are often otherwise asymptomatic or may have associated mild discomfort, tenderness and/or watering.
Episcleritis is typically classified into:
- Simple episcleritis where the redness is usually sectorial, often medial to the limbus, but rarely can be diffuse involving the entire episclera
- Nodular episcleritis characterised by a localised area of inflammation with a central raised nodule
Generally no specific treatment is required for episcleritis and it usually resolves over 7-10 days. Patients should be reassured that it is not generally associated with any systemic diseases. Topical non-steroidal anti-inflammatory agents (or occasionally mild steroids) can help if there is significant discomfort.
In contrast scleritis is a much rarer potentially blinding ocular inflammatory condition. It occurs more commonly in older women and is usually associated with an underlying systemic disease. Symptoms develop over a few days and include redness, tenderness and severe ocular pain (which can affect sleep). Unlike episcleritis the deeper inflamed vessels in scleritis do not blanch after the application of a topical vasoconstrictor eg phenylephrine.
Scleritis is typically classified depending on appearance and anatomical location:
- Diffuse scleritis
- Can be sectorial or involve the entire anterior segment
- Tends to be a less severe form of scleritis
- Approximately 30% have an underlying connective tissue disease
- Nodular scleritis
- Characterised by a deep purple-red nodule which, in contrast to nodular episcleritis, cannot be moved using a cotton-tip applicator
- Necrotizing scleritis with inflammation
- Represents the most severe destructive form of anterior scleritis
- Often bilateral and associated with systemic disease
- Sight threatening complications include keratitis, iritis, cataract and secondary glaucoma
- Carries a significant mortality rate due to vasculitis and requires high dose systemic immunosuppression
- Necrotizing scleritis without inflammation (scleromalacia perforans)
- Usually asymptomatic, occurring in patients with long-standing rheumatoid arthritis
- Sclera progressively thins revealing the underlying darker uveal tissue
- No effective treatment but perforation is rare
Patients may present with pain, tenderness, reduced vision, proptosis or restricted eye movements. Typical findings include choroidal folds, swollen optic disc and occasionally exudative retinal detachment. Thickened posterior coats can be confirmed using B-scan ultrasonography. Posterior scleritis is not usually related to any systemic disease.
All patients with scleritis require a complete assessment in order to try and establish a cause. Attention should be focussed on possible systemic aetiologies including:
- Infections like herpes zoster, tuberculosis and syphilis
- Autoimmune conditions such as rheumatoid arthritis, systemic lupus erythematosus and ankylosing spondylitis
- Vasculitidies including granulomatosis with polyangiitis (GPA), formerly known as Wegener's granulomatosis, and polyarteritis nodosa