Retrobulbar Tumors

Fig. 3.16  Optic disc tuber. This unusual patient with tuberous sclerosis had a slowly enlarging tuber within left optic disc. Visual acuity remained 20/20 over 10 years of observation. With permission from Brodsky and Safar64

Fig. 3.17  Optic disc glioma in a patient with NF2 (courtesy of Klara Landau, M.D.)

Fluorescein angiography shows a prominent network of fine “filigree” blood vessels in the superficial portion during the venous phase, and intense late staining of the tumor.189,191,507 Depending on their stage of evolution, these tumors are composed of either spindle-shaped astrocytes or acellular, laminated calcific concretions.189,380

Although these lesions rarely only enlarge, Shields et al described visual loss secondary to massive enlargement of astrocytomas of the retina and optic disc in four patients with tuberous sclerosis.508 In contrast, Brodsky and Safar64 described an enlarging tuber that was contained within the optic disc of one eye (Fig. 3.16). Despite its impressive enlargement and increasing surface vascularity, this lesion remained visually inconsequential over 10 years of observation. Intracranial lesions in children with tuberous sclerosis may cause obstructive hydrocephalus, papilledema and, eventually, optic atrophy.145,412 The associated CNS and systemic signs of tuberous sclerosis are discussed in Chap. 11.

Optic Disc Glioma

Optic disc glioma (Fig. 3.17) is an extremely rare tumor that appears as a mass of whitish, gray, or yellow tissue protruding fromthediscsurface.380 Visualacuityisvariablyaffected.Dossetor et al132 recently reviewed all previously reported cases and established the strong association of optic disc glioma with NF-2.

Combined Hamartoma of the Retina and RPE

Combined hamartomas of the retina and retinal pigment epithelium (CHRPE) are irregular, elevated, variably pigmented

lesions characterized by a proliferation of the retinal pigment epithelium (RPE), retina, and overlying vitreous. They have a predilection for the juxtapapillary area and are often accompanied by significant wrinkling and distortion of the retina. Combined hamartomas may elevate a portion of the optic disc and leak fluorescein. Conversely, chronic papilledema rarely produce a constellation of juxtapapillary pigmentary, vascular, and glial changes that is indistinguishable from a combined hamartoma.255 Gass189 described an older adult in whom a small depigmented juxtapapillary CHRPE produced elevation of the disc, with segmental leakage on fluorescein angiography, simulating ischemic optic neuropathy. Landau et al328 established the association of CHRPE with NF-2 that has been confirmed in subsequent studies.209,289,518

Retrobulbar Tumors

The finding of optic disc swelling in a proptotic eye (usually with decreased acuity) is highly suggestive of a retrobulbar tumor. Intrinsic optic nerve tumors may compress and/or infiltrate the optic nerve and interrupt axonal transport, leading to swelling of the optic disc. Optic nerve glioma is the most common retrobulbar tumor associated with optic disc swelling in children. While it has been found experimentally that extrinsic optic nerve compression must occur in close proximity to the globe to produce optic disc edema, many clinical exceptions to this rule have been documented.380 Orbital venous stasis may be a predominant mechanism whereby mass lesions in the posterior orbit lead to optic disc edema.

Optic nerve sheath meningioma is rare in children. When present, it produces gradual visual loss, optic disc swelling, and proptosis. This tumor can usually be differentiated from