Episcleritis
Synonyms and keywords:

# Overview
Episcleritis is an acute, recurrent, benign inflammatory condition
-f the loose connective tissue lying superficial to the sclera and deeper to the conjunctiva.

# Classification
Inflammation of the episclera is classified by its location and severity using the system devised by Watson.

# Pathophysiology
The exact pathogenesis of Episcleritis is not fully understood.

# Causes
Episcleritis has been associated with a large number systemic morbidities. The commoner systemic conditions associated with episcleritis are atopy Rheumatoid arthritis, Spondyloarthritis, Inflammatory bowel disease, Systemic lupus erythematosus, Relapsing polychondritis, Gout. Rarely it may be associated with IgA nephropathy, Lyme disease and drug reaction to pamidronate.
Acne rosacea is the commonest ocular comorbid condition with
episcleritis and is typically seen in patients with eyelid and corneal
involvement. The ocular disease often precedes dermatological manifestations.
Episcleritis is also frequently seen as part of the spectrum of
atopic keratoconjunctivitis and dry eye syndrome.

# Epidemiology and Demographics
Episcleritis is overwhelmingly a disease of adults affecting a wide range of age groups; pediatric age group involvement is rare. The sex distribution varies between published
series but those series that describe an association with rheumatic diseases tend to have a female preponderance. Episcleritis is uncommon and the exact etiology of episcleritis is difficult to ascertain. 
Diffuse episcleritis is more common than nodular episcleritis.The majority of patients with episcleritis have mild evanescent disease that usually does not require ophthalmological intervention and treatment.

# Risk Factors
There are no established risk factors for Episcleritis.

# Clinical Presentation
The onset of episcleritis is usually acute and the patient presents with discomfort rather than severe pain .The pain if present in Episcleritis is usually a  mild discomfort and localized to the eye, rather than the typical boring pain associated with severe headache in scleritis.
Rarely, episcleritis may be associated foreign body sensation and epiphora. The hallmark signs of episcleritis are oedema and inflammation of the episclera and injection and dilatation of the episcleral blood vessels. The sclera and subtarsal conjunctiva are not involved but
the conjunctiva overlying the inflamed area is always affected. There is no scleral swelling or necrosis and the intraocular structures
are typically not involved. The visual acuity is normal as long as there is no co-morbidity.
In diffuse episcleritis there is diffuse swelling and
-edema of a sector of the episclera in around two-thirds of patients
-r of the whole eye in around one-third of patients. The redness varies in intensity, but is always red or pink
(rather than the bluish, brawny red colour seen in diffuse scleritis),
and the episcleral vessels, although engorged, retain their characteristic radial orientation.
The eye is generally not tender to touch. In nodular episcleritis , the oedema and infiltration is
localized to one part of the globe. A raised nodule forms within
the episcleral tissue. It is bright red to pink in colour and often has overlying or surrounding vascular irregularity. The nodule may be
tender to touch and is usually mobile. There is generally only one nodule at any one time and the nodules do not undergo necrosis.
Careful slit lamp examination of the episclera, sclera, and the blood vessels is essential to differentiate episcleritis from scleritis.
In patients with episcleritis there is oedema of the episclera and
dilatation of the conjunctival vessels. There is no oedema of the underlying sclera. The lack of scleral involvement is often easiest
to appreciate using red-free light and after blanching the superficial conjunctival vessels with phenylephrine 10%. After an attack of episcleritis the eye returns completely to normal,
but after repeated attacks over a long period of time there
may be some mild scleral thinning.

# Screening
There is insufficient evidence to recommend routine screening for Episcleritis.

# Natural History, Complications, and Prognosis
Episcleral inflammation adjacent to the cornea can lead to mild peripheral corneal infiltrate or oedema, and
the peripheral cornea can be left thinned or vascularized. Recurrent attacks of episcleritis over a long time can cause mild scleral thinning, which is of no consequence to the integrity of the eye. The most common complications seen in patients with episcleritis are related to the use of long-term topical corticosteroids.
The use of long-term topical corticosteroids can lead to Cataract, ocular hypertension, and steroid-induced glaucoma. Rarely, topical corticosteroids may also induce herpetic
keratitis. These treatment-related complications are the commonest causes of visual loss in patients with episcleritis.

# Diagnosis
When diagnosed clinically, a small number of
serological tests to ascertain associative autoimmune diseases like rheumatoid arthritis or systemic lupus
erythematosus may be useful.
Anterior segment fluorescein angiography in episcleritis reveals
a normal vascular pattern but the flow rate is generally faster than
normal and the whole transit of dye may be completed within two
to three seconds.
High definition anterior segment ultrasound helps in differentiating episcleritis from scleritis but is rarely
necessary clinically.

# Treatment

## Medical Therapy
Episcleritis is a self-limiting disease, thus it doesn't frequently require any treatment. If the symptoms are severe to require treatment, topical steroids generally
provide rapid symptomatic relief and have proven benefit over
topical non-steroidal anti-inflammatory treatment and topical
lubricants.
Systemic treatment with oral non-steroidal antiinflammatory
drugs such as cyclo-oxygenase inhibitors, may be
required for episcleritis. In general any systemic disease should be
treated on its merits and the episcleritis treated as necessary.
Any local ocular disease, such as acne rosacea, atopy, or
keratoconjunctivitis sicca that may be causing or contributing to
the episcleritis, should be treated aggressively.