Something is wrong with my eye

AORN Journal, April, 2008 by Nancy J. Girard

The Case

A 36-year-old woman with no significant past medical history underwent a right nephrectomy in the left lateral position. The surgery was uncomplicated her blood pressures intraoperatively were within 20% of her baseline, and she did not have significant blood loss. Immediately after surgery, the patient complained of "blurriness" in one eye. This was attributed to eye ointment applied during the surgery, and no further workup was pursued.

During a clinic visit two weeks later, the patient complained of blindness in her left eye. She was emergently referred to an ophthalmologist and diagnosed with retinal ischemia as a complication of surgery. Three months after surgery, the patient still had partial visual loss.

Discussion

Postoperative visual loss (POVL) may occur even in healthy patients who undergo seemingly uncomplicated surgery. The incidence of visual complications after surgery is low but has been reported to be as high as one in 500 patients after spinal procedures and one in 60 patients after cardiac procedures. (1,2) Patients may not tell their nurses or physicians about eye problems immediately after surgery, either because of their altered mental status or their mistaken belief that the visual changes are caused by residual ointment or anesthetic effects. The most common POVL defects are

* anterior ischemic optic neuropathy (ION),

* posterior ION,

* central retinal artery occlusion (CRAO), and

* cortical blindness.

Anterior ION occurs at the optic nerve head where the optic nerve and retinal vessels enter the eye globe. Anterior ION has been associated primarily with cardiac bypass procedures, but it can occur during spinal surgeries for which the patient is in the prone position and in other procedures. Visual loss secondary to anterior ION has been reported to occur at any time from the immediate postoperative period to a few weeks after surgery.

Posterior ION occurs anywhere posterior to the optic nerve head to the optic nerve chiasm. Posterior ION is most commonly associated with spine procedures in the prone position and bilateral radical neck procedures. Some cases have occurred in patients who had their heads placed in Mayfield pins and whose eyes were free from external pressure. (3)

Incidences of ION in patients having spinal surgery have been associated with large operative blood loss (ie, median 2.3 L) and long duration in the prone position (ie, median eight hours). Since ION has been reported outside the operative arena in critically ill patients, it seems unlikely that anesthetic agents such as thiopental and volatile agents are significant etiologic factors. (4) In slightly more than half of the ION cases reported, both eyes were affected, which is consistent with a systemic event. (3) Complete recovery from either anterior ION or posterior ION is rare, and patients frequently are left with a visual field defect at a minimum.

Central retinal artery occlusion is the sudden blockage of the blood supply to the retina, often referred to as a "stroke" of the eye. The horseshoe headrest has long been associated with CRAO because of its firmness and close position to the eye with poor accessibility. Soft foam cushions and gel pads also can cause CRAO, however, if they are not positioned correctly.

Cortical blindness is the loss of sight caused by an organic lesion in the visual cortex. It most often occurs in association with cardiac bypass procedures and usually is associated with embolic events or profound hypotension.