Case of ischemic optic neuropathy developed eleven days after an aortic arch replacement

We present a case of ischemic optic neuropathy (ION) developed 11 days after an aortic arch replacement in a 59 year-old male who had a history of untreated hypertension. Thoracic CT revealed severe stenosis of the right common carotid artery with poor blood flow. Aortic clamping time was 96 minutes, and selective cerebral perfusion time was 48 minutes. The lowest hemoglobin concentration of venous blood during cardiopulmonary bypass was 8.1 g/dl and the lowest arterial pressure was 60 mmHg. Due to pulmonary congestion, artificial ventilation was required until 11 post-surgical days. After removal of ventilator, the patient's consciousness was clear with no motor paralyses evident. However, the patient complained of blurred vision on that day. Bilateral papillae of the optic fund were pale. Atrophy of the papillae was also noted. Visual evoked potential was bilaterally flat suggesting bilateral optic nerve disturbance. The diagnosis of ION was made by ophthalmologist and neurologists. We speculated that low hemoglobin level during cardiopulmonary bypass was not the sole etiology of ION. Untreated hypertension, low blood flow through internal carotid artery and prolonged mechanical ventilation were also deteriorating factors of ION in this patient. We should be alert to prevent ION in such a complicated case.