Optic nerve sheath fenestration (medial upper lid) #2
This is Richard Allen at the University of Iowa.
This video demonstrates an additional example of an optic nerve sheath fenestration through the medial upper eyelid crease.
4-0 silk sutures have been placed through the eyelid margin. A 7-0 Vicryl suture is placed through the superior medial limbus, partial thickness, to provide traction during the case. A 15 blade is then used to make an incision along the upper eyelid crease through the skin and orbicularis muscle. Dissection is then carried out superiorly between the orbital septum and the orbicularis muscle to provide exposure. The orbital septum is opened and the underlying pre-aponeurotic fat is identified. Dissection will then be carried out between the pre-aponeurotic fat pad and the medial fat pad. Malleable retractors will be introduced to continue dissection between the two fat pads toward the optic nerve. The eye is then placed in infra and AB duction with the 7-0 vicryl traction suture. The small malleable retractors are then used to dissect in the area between the medial fat pad and pre-aponeurotic fat. This dissection should essentially be performed so that you are following the contour of the globe posteriorly. After the optic nerve is identified, moistened neurosurgical cottonoids are used to pack around the nerve. The purpose of these cottonoids is to pack the fat away from the nerve.
The surgeon now switches to the microscope and the view is the surgeon's view from the head. The malleable retractors are placed back into position where the optic nerve is identified. The zoom is used on the microscope. One can appreciate the dilated optic nerve sheath in this patient with idiopathic intracranial hypertension. Meringotomy forceps are then used to grasp the optic nerve sheath. The Yasargil neurosurgical scissors are then used to make an incision through the optic nerve sheath where a gush of fluid is noted. The straight neurosurgical scissors are the used to make a window in the optic nerve sheath, dissecting between the nerve sheath and the underlying optic nerve. Some people will make slits in the optic nerved sheath, I prefer a window. The curved neurosurgical scissors will then be used to cut across the posterior aspect of the fenestration to excise the sheath. This exposes the underlying optic nerve. The sheath can be sent to the pathologist if preferred. Inspecting the area shows no bleeding. The malleables are slowly withdrawn, followed by the neurosurgical cottonoids.
We now switch back to the initial camera. The traction sutures have been removed. The eyelid crease is closed with superficial interrupted 6-0 Prolene sutures. At the conclusion of the case, antibiotic ointment is placed over the incision and the patient will return in one week for reevaluation and suture removal.