Anthony Aldave

BASICS

DESCRIPTION

• 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

EPIDEMIOLOGY

Incidence

• There are no incidence values.

– Rare; patients are often misdiagnosed

Prevalence

• There are no prevalence values

• Patients are often misdiagnosed

• First described in Germany

• Has now been described worldwide

RISK FACTORS

Family History (affected parent).

Genetics

• Autosomal dominant inheritance, incomplete penetrance

• Mutation in KRT3 (1) (chromosome 12q13) and KRT12 (chromosome 17q12) (2) genes

• Genes code cornea specific proteins K3, K12

PATHOPHYSIOLOGY

• 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.

ETIOLOGY

Genetic inheritance

COMMONLY ASSOCIATED CONDITIONS

Other corneal dystrophies may coexist (4).

DIAGNOSIS

HISTORY

• 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

Pediatric Considerations

Can be a cause of corneal erosions in children.

PHYSICAL EXAM

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

Lab

Blood or saliva can be collected and sent for screening of KRT3 and KRT12 to differentiate from conditions with similar phenotypes.

Imaging

• Indirect slit-lamp illumination from the iris reveals a dust-like pattern.

• Slit-lamp retroillumination bubble-like cysts

Diagnostic Procedures/Other

• Histology and electron microscopy are useful with tissue samples from corneal biopsy or lamellar/penetrating keratoplasty.

• Confocal microscopy for in vivo study (3)

Pathological Findings

• 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.

DIFFERENTIAL DIAGNOSIS

• Epithelial basement membrane dystrophy

• Bleb-like variant of EBMD

• Lisch corneal dystrophy

• Limbal stem cell deficiency

• Epidermolysis bullosa

TREATMENT

MEDICATION

First Line

• Most do not require treatment

• If symptomatic, frequent lubrication with artificial tears or ointments for discomfort

Second Line

Bandage soft contact lenses.

Stay updated, free articles. Join our Telegram channel

Join