• Meesmann’s corneal dystrophy (MCD) is an epithelial dystrophy
• Occurs early in life
• Also called Juvenile epithelial dystrophy
– Autosomal dominant inheritance
– Characterized by epithelial microcysts
– Cysts contain degenerated cell products
• There are no incidence values.
– Rare; patients are often misdiagnosed
• There are no prevalence values
• Patients are often misdiagnosed
• First described in Germany
• Has now been described worldwide
Family History (affected parent).
• Autosomal dominant inheritance, incomplete penetrance
• Genes code cornea specific proteins K3, K12
• K3 and K12 proteins form meshwork filaments found in the epithelial cell cytoplasm.
• The meshwork maintains epithelial integrity, provides resistance to mechanical stress (3).
• Pain results from cyst rupture.
• Cysts appear early in life, increase with age.
• Blurry vision evolves from increased cyst formation and corneal surface irregularity.
• Scarring may develop after repeat erosions.
COMMONLY ASSOCIATED CONDITIONS
Other corneal dystrophies may coexist (4).
• Usually asymptomatic or have mild symptoms
• May have episodes of photophobia, tearing, blepharospasm, foreign body sensation, and mild pain from erosions due to cyst rupture
• Significant visual loss is uncommon
Can be a cause of corneal erosions in children.
Multiple tiny, intraepithelial, microcystic, bubble-like lesions and dot-like opacities (5)
• Usually bilateral and symmetric
• Can be unilateral
• Surrounding epithelium is usually clear
• Usually cysts are most prevalent in the interpalpebral zone or involve the entire epithelium, extending to the corneal limbus.
• Cysts may involve only the periphery, usually with spared central cornea.
• Punctate epithelial erosions, mild injection
• Central scarring, subepithelial serpiginous lines and opacities in advanced cases
DIAGNOSTIC TESTS & INTERPRETATION
Blood or saliva can be collected and sent for screening of KRT3 and KRT12 to differentiate from conditions with similar phenotypes.
• Indirect slit-lamp illumination from the iris reveals a dust-like pattern.
• Slit-lamp retroillumination bubble-like cysts
• Histology and electron microscopy are useful with tissue samples from corneal biopsy or lamellar/penetrating keratoplasty.
• Confocal microscopy for in vivo study (3)
• Intraepithelial cysts, 10–70 μm in diameter
• Cysts are filled with PAS-positive granules, (5) and fibrogranular material termed “peculiar substance.”
• Epithelial basement membrane is irregular, showing thickening and multilaminarity.
• Some cases have thinning of the cornea.
• Advanced disease shows disorganized epithelium with loss of cell polarity.
• Epithelial basement membrane dystrophy
• Bleb-like variant of EBMD
• Lisch corneal dystrophy
• Limbal stem cell deficiency
• Epidermolysis bullosa
• Most do not require treatment
• If symptomatic, frequent lubrication with artificial tears or ointments for discomfort
Bandage soft contact lenses.
Patients and ophthalmologists must be aware of the increased risk for infectious keratitis.