Background
Episcleritis is an inflammatory condition affecting the episcleral tissue that lies between the conjunctiva and the sclera.[1, 2] Episcleritis is usually a mild, self-limiting, recurrent disease. Most cases are idiopathic, although up to one third have an underlying systemic condition. Some cases may be caused by exogenous inflammatory stimuli.[3, 4, 5]
Pathophysiology
The pathophysiology is poorly understood. The inflammatory response is localized to the superficial episcleral vascular network, and histopathology shows nongranulomatous inflammation with vascular dilatation and perivascular infiltration.
The 2 clinical types are simple and nodular.
The most common type is simple episcleritis, in which there are intermittent bouts of moderate-to-severe inflammation that often recur at 1- to 3-month intervals. The episodes usually last 7-10 days, and most resolve after 2-3 weeks. Prolonged episodes may be more common in patients with associated systemic conditions. Some patients note that episodes are more common in the spring or fall. The precipitating factor is rarely found, but attacks have been associated with stress and hormonal changes.
Patients with nodular episcleritis have prolonged attacks of inflammation that are typically more painful than simple episcleritis. Many patients with nodular episcleritis have an associated systemic disease.
Epidemiology
Frequency
United States
True frequency is difficult to determine since many patients do not seek medical attention.
Sex
Some authors report no difference, while other authors report that up to 74% of cases occur in females.
Age
Episcleritis is most common in the fourth to fifth decades.
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