Dellen.

-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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