Ophthalmoscopy

Compressive optic neuropathy may occur in patients with orbital disease. The typical features of an optic neuropathy may be present, including visual acuity loss, visual field loss, and a relative afferent pupillary defect. The optic disk in these cases may be normal (i.e., retrobulbar optic neuropathy), swollen, or pale (Figure 7.3). In most cases, if the compressive lesion is producing optic disk edema, it will be located more anteriorly in the eye, orbit, or the optic canal. In-tracranial lesions are less likely to produce compres-sive optic disk edema, although if large enough may

FIGURE 7.2. Ocular motility photos show an elevation deficit and ptosis (A) due to a frontal sinus mucocoele (B).

FIGURE 7.2. Ocular motility photos show an elevation deficit and ptosis (A) due to a frontal sinus mucocoele (B).

produce papilledema (disk edema due to increased intracranial pressure). Optic disk edema that is longstanding may compress the central retinal venous circulation, and collaterals between the retinal and choroidal circulations may form to bypass this obstruction. These new blood vessels are referred to as optociliary shunt vessels (although technically they are collateral vessels and not shunts). Optic nerve collaterals in the setting of compressive optic neuropathy (e.g., progressive visual loss and optic atrophy) are a sign of orbital tumor, usually optic nerve sheath meningioma, or, less likely, optic nerve glioma.

0 0

Post a comment