Familial Drusen are also known as Dominant Drusen of Bruch's
Membrane. It is still controversial whether they represent a distinct
entity or are just an early manifestation of AMD and are the same
acquired degenerative drusen of senescence .
Familial drusen follow an autosomal dominant pattern of inheritance. The onset
of symptoms is during the third or fourth decade (earlier than AMD).
Drusen are bilaterally, symmetric, multiple, deep, yellow -white lesions.
Paitents become symptomatic from an associated exudative or non-exudative
detachment, at the level of the RPE.
Fluorescin angiography reveals RPE transmission corresponding to the areas
of drusen deposition and overlying RPE atrophy /thinning. Occasionally a
neovascular membrane is revealed.
ERG is usually normal, while the EOG is subnormal especially in advanced disease.
Visual fields, dark adaptation and color testing are normal.
Histopathologic studies discriminate between inherited and age-related drusen.
Inherited dominant drusen are nodular thickening of the RPE basement
membrane, at least early in the disease.
Age-related degenerative drusen are focal collections of eosinophilic homogenous
material lying between the BM of the RPE and the collagenous portion
of Bruch's membrane. EM studies demonstrate that drusen are conglomerates
of denatured mitochondria, pigment granules, photoreceptors remnants,
residual bodies and debris from degenerating RPE.
Chemically they consist
of cerebroside and sialic acid, sometimes bound to mucin.
Unfortunately, there is no known treatment proven effective
for dominant drusen.