Acute severe irreversible visual loss with sphenoethmoiditis-'posterior' orbital cellulitis.

Orbital cellulitis secondary to adjacent paranasal sinusitis presents with marked proptosis, ophthalmoplegia, eyelid edema, chemosis, and/or conjunctival hyperemia. These conditions often precede visual dysfunction. "Posterior" orbital cellulitis secondary to sphenoethmoidal sinusitis may be defined as the clinical syndrome in which early severe visual loss overshadows or precedes accompanying inflammatory orbital signs. The visual loss may be attributed to involvement of the intracanalicular or orbital apical segment of the optic nerve. Total irreversible unilateral visual loss developed in three patients with this syndrome. Severe visual loss was preceded by diplopia in one patient and by bilateral eyelid edema in another. One patient with chronic panparanasal sinusitis with acute visual loss presented with isolated optic disc edema. Proptosis and ductional restriction subsequently developed. The irreversible blindness in these cases may be due to a combination of intracanalicular edema and vasculitis causing optic nerve infarction.