The objective of the present study was to estimate the efficacy of the optical systems with the variable visual field angle applied for the endoscopic interventions on the paranasal sinuses. The authors report a clinical observation of the patient presenting with the giant fungal body in the sphenoidal sinus responsible for the partial destruction of the bone canal of the optic nerve and the internal carotid artery. The patient was treated by endoscopic shenoidotomy through the paraseptal approach with the use of a sinuscope with the variable visual field angle. It was shown that the use of optical devices with the variable visual field angle makes it possible to significantly reduce the duration of the surgical intervention, facilitates orientation in the difficult-of-access regions , and ensures adequate control during the removal of neoplasms at the basis of the skull.