“Thiel-Behnke Corneal-Dystrophy”, Victor McKusick, Mendelian Inheritance in Man, 1966. icd10=H18.5

INTRODUCTION.

Thiel–Behnke corneal dystrophy (TBCD) is an autosomal dominant inherited disorder affecting the cornea, specifically the Bowman’s layer. It is a type of anterior corneal dystrophy and is characterized by abnormal deposition in the superficial cornea, leading to visual symptoms.

Clinical Features.
Age of onset: Usually in childhood or early adolescence.
Symptoms:
Progressive decrease in visual acuity
Recurrent corneal erosions causing pain, photophobia, tearing
Signs:
Honeycomb-shaped opacities in the superficial cornea (seen on slit-lamp exam)
Often bilateral and symmetric
Opacities predominantly in the central cornea
Genetics
Inheritance: Autosomal dominant
Gene: Most cases are linked to TGFBI (Transforming Growth Factor Beta Induced) gene mutations.
Pathophysiology: Mutation leads to abnormal protein deposits in Bowman’s layer, causing the characteristic honeycomb pattern.
Diagnosis
Slit-lamp examination: Honeycomb-like subepithelial opacities.
Anterior segment OCT: May show hyperreflective deposits in Bowman’s layer.
Histology: “Curly fibers” pattern is characteristic in TBCD.
Differential Diagnosis:
Reis-Bücklers corneal dystrophy (RBCD):
Also affects Bowman’s layer
Shows rod-shaped opacities rather than honeycomb
Usually earlier onset and more aggressive
Management
Symptomatic treatment:
Artificial tears
Bandage contact’ lenses for recurrent erosions
Surgical Options:
Phototherapeutic keratectomy (PTK): Removes superficial opacities, improves vision
Corneal transplantation (lamellar or penetrating keratoplasty): For severe cases 
Recurrence after surgery is common, though usually slower than in RBCD.
Prognosis:
Vision generally preserved until later life, but recurrent erosions can affect quality of life.
Recurrence after PTK is slow, and visual prognosis is generally good compared to other anterior corneal dystrophies.

There is evidence that Thiel–Behnke corneal dystrophy is caused by mutation in the (TGFBI) encoded on genomic coordinate 5:136,028,988 and cytoband 5q31.1 in humans.