Everything about Drusen totally explained
Drusen (singular, "druse") are tiny yellow or white accumulations of extracellular material that build up in
Bruch's membrane of the
eye. The presence of a few small ("hard") drusen is normal with advancing age, and most people over 40 have some hard drusen. However, the presence of larger and more numerous drusen in the
macula is a common early sign of age-related
macular degeneration (AMD).
Classification
Drusen associated with aging and macular degeneration are distinct from another clinical entity,
optic disc drusen, which is present on the
optic nerve head. Both age-related drusen and optic disc drusen can be observed by
ophthalmoscopy.
Whether drusen promote AMD or are symptomatic of an underlying process that causes both drusen and AMD isn't known, but they're indicators of increased risk of the complications of AMD.
Pathophysiology
Drusen were initially described by Donders who named them for the German word for
geode, based on their glittering appearance. In view of their location between the
retinal pigment epithelium (RPE) and its vascular supply, the
choriocapillaris, it's possible that drusen deprive the RPE and
photoreceptors of oxygen and nutrients. Interestingly, drusen always develop above the so called pillars of
choriocapillaris that's the area between two microvessels.
The source of the
proteins and
lipids in drusen is also not clear, with potential contributions by both the RPE and the
choroid. Several trace elements are present in drusen, probably the most concentrated being zinc. The protein composition of drusen includes
apolipoproteins and members of the
complement system. Zinc in drusen have been suggested to play a role in drusen formation by precipitating and inhibiting the elements of the complement cascade, especially complement factor H.
The presence of molecules that regulate
inflammation in drusen has led some investigators to conclude that these deposits are product of the
immune system.
Further Information
Get more info on 'Drusen'.
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