Meesmann corneal dystrophy (MECD) is a rare genetic condition affecting the clear front covering of the eye (cornea). It is characterized by the development of multiple tiny round cysts in the outermost layer of the cornea (corneal epithelium). Over time, these cysts can break open (rupture) and cause irritation and erosions. Symptoms usually appear around adulthood and may include light sensitivity (photophobia), redness, and pain. Vision remains good in most individuals, but some individuals can have temporary episodes of blurred vision. MECD can be caused by mutations in the either the KRT3 gene or the KRT12 gene and is inherited in an autosomal dominant fashion. While there is no cure for MECD, symptoms are usually effectively managed with use of lubricating eye drops.

Individuals with Meesmann corneal dystrophy usually do not have symptoms until adulthood, when the cysts on the cornea break open (rupture) and cause irritation and recurrent erosions. Symptoms may include light sensitivity (photosensitivity), contact lens intolerance, redness, pain, twitching of the eyelids (blepharospasm), increased tear production, the sensation of having a foreign object in the eye, and occasionally blurred vision (irregular corneal astigmatism).

KRT12 or KRT3 gene. These genes are thought to play an important role in maintaining normal corneal epithelial function.