Dellen

Synonyms

Delle (singular)

Definition

First described in 1911, dellen are saucer-like depressions in the corneal surface, typically at the corneal margin, caused by interruptions of the tear film and resultant local dessication of the cornea. Surface elevations such as those produced by dermoids, pterygia, large filtration blebs, significant chemosis, or tissue interruption from a limbal approach to muscle surgery prevent the eyelid from adequately resurfacing the cornea with tear fluid during blinking. Local stromal dehydration and thinning are accompanied by punctate irregularities of the epithelium, mild discomfort, or rarely pain. Treatment with frequent ocular lubrication, with or without a bandage contact lens, restores stromal hydration and provides symptomatic relief. Surgical management (e.g., bleb revision) is reserved for severe cases that are unresponsive to medical therapy. Though rare, untreated dellen can cause descemetocele formation or lead to corneal perforation.