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

Abstract

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.

Extensive Allergic Fungal Rhinosinusitis: Ophthalmic and Skull Base Complications

“…Optic neuritis due to the inflammatory process and critical retinal artery occlusion seem to be the underlying factors responsible for sudden vision loss in AFRS. This is supported by the fact that Thakar et al [10] and Gupta and colleagues [7] reported good recovery of vision in cases of sudden or recent onset visual loss after surgical decompression and steroid use.…”

“…Ophthalmic manifestations range from proptosis most commonly [9,13] to vision loss in extreme cases [7][8][9][10]. Vision loss is an extremely uncommon complication of AFRS with either a sudden acute [7,10] or gradually progressive mode of presentation [10].…”

“…The mode of presentation and treatment outcomes differ in both forms of visual loss indicating a difference in respective pathologies. Common to most or all patients exhibiting visual loss is near-total erosion of the bony optic canal in the sphenoid sinus with direct neural exposure to the fungal debris and polypoidal or diseased mucosa [7,10]. Proposed mechanisms of visual loss in sinonasal disease include optic neuritis due to an adjacent inflammatory process, central retinal artery occlusion or optic nerve venous congestion [17].…”

“…Aggressive bone erosion in AFRS can lead to a myriad of skull base and ophthalmic complications leading to significant morbidity and possibility of mortality [6][7][8][9][10].…”

“…Though reports and descriptions of such cases are found in the literature [6,7,11,12], an insight into surgical planning and intra-operative considerations is often lacking.…”