Meesmann

Meesmann epithelial corneal dystrophy (MECD), also known as Meesmann dystrophy or Meesmann keratopathy, is a rare hereditary disorder of the corneal epithelium. It is most commonly inherited in an autosomal dominant pattern and is caused by pathogenic variants in the keratin genes KRT12 and KRT3, which encode proteins critical for epithelial cell integrity.

Genetic and pathophysiological basis: Mutations in KRT12 or KRT3 disrupt the intermediate filament network in corneal epithelial cells, leading to increased fragility and the formation of tiny intraepithelial cysts. This structural disruption results in recurrent epithelial erosions and irritation.

Clinical features: MECD typically presents in childhood or adolescence with symptoms such as ocular irritation, photophobia, tearing, and episodic blurred vision. On slit-lamp examination, numerous clear microcysts are seen within the corneal epithelium, often concentrated in the central cornea. Visual acuity is usually preserved unless erosions or scarring occur.

Diagnosis: Diagnosis is based on clinical findings of diffuse epithelial microcysts and a compatible family history, with genetic testing confirming mutations in KRT12 or KRT3. The condition should be differentiated from other epithelial dystrophies and surface disorders such as map-dot-fingerprint dystrophy.

Management and prognosis: Treatment is supportive and aimed at reducing symptoms and preventing erosions. Options include frequent artificial tears or lubricants, hypertonic saline for ocular surface support, and lubricating ointments. In cases of recurrent erosions, bandage contact lenses may be used; ablative procedures like phototherapeutic keratectomy or keratoplasty are reserved for visually significant or refractory cases. The prognosis is generally good, with ongoing management focused on comfort and prevention of epithelial breakdown.