Bietti crystalline dystrophy

Bietti Crystalline Dystrophy

•Crystalline corneo-retinal dystrophy is an uncommon hereditary condition

•First reported by Bietti in 1937 as a corneo-retinal degeneration

•Second or third decade of life 

•Autosomal recessive  CYP4V2 Gene or dominant disorder.•

•Crystals consists cholesterol or cholesterol ester and complex lipid inclusions

•Two subtypes of Bietti's crystalline dystrophy :

üa localised type with findings confined to the posterior pole

üa diffuse type with widespread retinal findings

• Fluorescein angiographic findings depend on the

-Degree of RPE atrophy,

-Pigment mottling,

-Crystal deposition and

-Atrophy of choriocapillaries.

•The ERG

-Low normal to moderately abnormal in the localised type

-Severely subnormal to non-recordable in the diffuse type

OCT

- Shows crytalline hyperreflectivity in all layers of retina

- Thinning of choriocapillaries

These patients have high risk of developing CNVM