Visual loss in the setting of allergic fungal sinusitis: pathophysiology and outcome.

OBJECTIVE To hypothesise the probable pathophysiological mechanism responsible for visual loss in allergic fungal sinusitis, other than direct compression. DESIGN Retrospective, non-randomised case series. Out of 274 cases of allergic fungal sinusitis, four cases with sudden visual loss were enrolled into the study. The fourth case had visual loss on the contralateral side to bony erosion of the lateral wall of the sphenoid sinus. INTERVENTIONS All four cases were evaluated with fungal smear, immunoglobulin (Ig) E titres, visual evoked potentials, non-contrast computed tomography and magnetic resonance imaging of the paranasal sinuses, and fundus examination. They then underwent endoscopic sinus debridement followed by intravenous methylprednisolone. OUTCOME MEASURES Improvement in vision. RESULTS All four cases experienced an improvement in vision: full recovery in three cases and partial improvement in one case. CONCLUSION In view of the operative, radiological and laboratory findings for case four, with the suggestion of a hyperimmune response to fungal antigens (in the form of raised IgE titre and positive fungal serology), we suggest that a local immunological reaction to fungal antigens might be responsible for the observed visual loss in cases of allergic fungal sinusitis, in addition to mechanical compression of the optic nerve.