Thiel-Behnke dystrophy

Genetics and background

Genetics

AR Autosomal recessive (AD)

Mutation

TGFBI, R555Q mutation (arginine by glutamine)

Laterality

bilateral

Symmetry

Yes

Systemic factors

No

Age of onset

during childhood; the cornea is normal at birth.

Location

Bowman's layer and anterior stroma.

At the slit lamp

Appearance

Granular opacities that spread to take on a geographic appearance. Sometimes similar to Reis-Bücklers on examination, apart from the honeycomb pattern, which is finer and less pronounced, in the form of an undulating fibrocellular deposit.

Symptoms and course

Recurrent pain or erosion

Yes, from an early age.

Visual acuity

decreases secondary to corneal scarring, but the decrease appears later than in Reis-Bücklers (50 years vs 20-30 years).

Diagnosis

Diagnosis:

• Histology: destruction of Bowman's layer with an epithelium composed of cells of irregular size and shape; a reduplicated and thickened basement membrane; disappearance of the basement membrane in many places; an undulating subepithelial fibrocellular tissue.
• Electron microscopy: undulating (curly) fibers are found at the level of Bowman's layer. These fibers are round or arcuate.
• Confocal microscopy: deposits with round borders, with a dark shadow and a lower reflectivity than in Reis-Bücklers.
• OCT: continuous, crenated, saw-tooth subepithelial hyperreflective band

Treatment

Recurrence +++ Recurrence on graft: Frequent