The episclera is the thin layer of vascular tissue overlying the sclera. Inflammation of this layer is referred to as episcleritis. It may be accompanied by scleritis.
It is a relatively common condition which is unilateral in two-thirds of cases. Both sexes are equally affected. It is benign and self-limited. Thirty percent are associated with general medical conditions such as collagen disease, herpes zoster, gout and syphilis. It is a good indicator of disease activity in inflammatory bowel disease, where it is one of the most common ocular manifestations (1).
There are two types - simple and nodular. Simple episcleritis is characterized by a very acute onset. It is mild, sectoral, recurrent and resolves rapidly. The nodular form presents as a localised, raised mobile area of inflammation near the limbus. The nodules may be single or multiple and usually recur.
Symptoms may include mild irritation and photophobia as well as red eye (2).
About 15% of patients develop a mild iritis. Episcleritis is distinguished from conjunctivitis by the localised response and the lack of palpebral conjunctival involvement. A drop of phenylephrine 2.5% causes visible blanching of the episcleral vessels in episcleritis, but will not do so in scleritis. Examination with a slit lamp microscope is also helpful in diagnosis (3).
- (1) Simon C. Inflammatory bowel disease. InnovAiT 2008;1(9):615-622
- (2) Bal SK et al. Red eye. BMJ. 2005; 331(7514): 438.
- (3) Smith JR. Therapy Insight: scleritis and its relationship to systemic autoimmune disease. Nature Clin Pract Rheumatol. 2007; 3: 219-226
Last reviewed 10/2020