-Caused by interruptions of the tear film and local dehydration of the cornea.
-Form a saucer-shaped excavation of the cornea that occurs adjacent to a limbal elevation.
ETIOLOGY:
-Secondary to paralimbal elevation due to :Episcleritis or scleritis, Thick pingecula or pterygium, Subconjunctival hemorrhage, Subconjunctival injections, Filtering blebs, Suture granuloma, Limbal tumours, Lesions like angioma, Subconjunctival silicone oil
-Post-surgery
-Long term contact lens wear
-Following paralytic lagophthalmos
-Secondary to severe conjunctival chemosis
-Idiopathic, in elderly people
-Ocular trauma
PATHOPHYSIOLOGY:
-Paralimbal elevation causes localised break in the precorneal oily tear film especially a focal absence of the mucin layer.
-Epithelium is hydrophobic and in absence of mucin will repel water and localized dehydration occurs producing a dry spot leading to a dry epithelial surface.
-This is followed by thinning of cornea in that area forming a dellen.
COMPLICATIONS:
-If left untreated, the underlying corneal stroma may undergo secondary degeneration, leading to corneal scarring and vascularisation.
-Can lead to infections and corneal perforation.
MANAGEMENT:
-Rapid re-establishment of the mucin layer and a hydrophilic corneal surface by:
-Frequent lubrication with artificial tears and ointments.
-Patching of eye.
-Large diameter BCL
-Surgical excision of paralimbal elevations.
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Image from Rajan Eye Care Hospital
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