Optic nerve head drusen: histopathological considerations--clinical features.

The histopathological features made on 18 autopsies have proved that the optic nerve head drusen are calcified formations situated within the margins of the optic nerve head. It has been supposed that not only an aberrant axoplasmic transport, but also the presence of local factors, partly depending on the Bruch's membrane, can play a determining role in the pathogenesis of the optic disc drusen. A spongiotic edema gives us the histopathological equivalent of the clinical aspect of the optic disc with indistinct margins and lack of the central cup and furthermore gives us an explanation about the perimetric alterations pathogenesis. Clinical observations confirm that the optic nerve head drusen are prevalently asymptomatic and that visual acuity remains unchanged. The threshold tests are able to quantify exactly the entity and the depth of the visual field defects and its possible changing within a certain period of time. As regards the diagnosis, the retinal fluoroangiography is of great importance allowing to distinguish clearly a pseudo-papillary edema from a papillary edema.