Anterior dystrophies
Thiel-Behnke dystrophy
Cues: AD/AR inheritance · graft recurrence +++ high ++ intermediate + low · bold = key terms · Differential diagnosis (blue) and Treatment (amber) boxes.
- 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.
- 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.
- 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:
- 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
Initially, treatment of the recurrent corneal erosions
Once the corneal scar has appeared, treatment varies:
- Superficial keratectomy with a blade and peeling of the scar
- PTK +/- mitomycin
- DALK
- Penetrating keratoplasty
Recurrence +++ Recurrence on graft: Frequent