4. Drusen of the Optic Nerve

Disorders of the Fundus Edited by Ronald E. Carr, MD (j)

4. Drusen of the Optic Nerve

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Drusen of the optic nerve is a bilateral disorder, inherited as autosomal dominant, with a predilection for the Caucasian race. Histopathologically drusen are acellular basophilic concretions which lie within the optic disc anterior to the lamina cribrosa. The exact pathogenesis of these concretions is unknown. Early in their course, most drusen are buried within the substance of the papilla and are not visible on fundus examination. They usually progress in size and extend anteriorly where, in some cases, they are easily seen on the surface of the disc (Fig 1), while in other patients, they may lead to an elevated disc. In the latter cir-

From the Department of Ophthalmology, New York University Medical Center, 550 First Avenue, New York, NY 10016.

cumstance the disc borders may be blurred either sectorially or diffusely. Since drusen may be associated with flameshaped subretinal peripapillary hemorrhages (Fig 2), as well as with various visual field scotoma (nerve fiber bundle, irregular peripheral constriction, enlarged blind spot), the major differential diagnosis is papilledema (Fig 3). Helpful diagnostic modalities include fluorescein angiography (which shows very late staining of the drusen) (Figs 2C, 2D), ultrasonography (as excellent reflectors of sound drusen persist at the lowest decibel level), and examination of older family members (who may exhibit drusen of the surface of the disc). On rare occasions drusen of the disc may be associated with a hemorrhagic maculopathy with peripapillary subretinal neovascularization (JIlustrations follow on pages 360 and 361) (Fig 4).

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Fig 1. Top left and right, the multiple refractile hyaline bodies lie superficially on the optic nerve head and are easily identified on funduscopy. Fig 2. The disc of the right eye has a peripapillary subretinal hemorrhage superonasally as well as a superficial hemorrhage on the surface of the disc (2A, middle left). The superonasal border of each disc is blurred and elevated (2A and B, middle left and right). On fluorescein angiography the drusen accumulate dye and can easily be identified in late phase (2C and D, bottom left and right).

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Fig 3. Top left , a swollen nerve head with peripapillary edema and hemorrhage is a result of drusen within the substance of the nerve. Fig 4. This 12-year-old girl had bilateral optic nerve head drusen associated in each eye with subretinal choroidal neovascularization and a hemorrhagic maculopathy (4A, top right). A large network of subretinal neovascularization with adjacent hemorrhage is noted on fluorescein angiography (4B, bottom left). Late stage fluorescein shows staining of drusen predominantly in the superotemporal portion of the disc as well as leakage from the neovascular network (4C, bottom right).

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