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Tất cả bệnh nhân đã phát triển đĩa quang teo. Khoảng 66% bệnh nhân có yếu tố nguy cơ mạch máu, chẳng hạn như cao huyết áp, đái tháo đường, tăng cholesterol máu, bệnh động mạch vành, suy tim sung huyết, loạn nhịp tim, béo phì, và sử dụng thuốc lá. Phần còn lại đã không có yếu tố nguy cơ mạch máu. | 2. Ischemic Optic Neuropathies 51 had a final visual outcome of hand motion or worse. All patients developed optic disc atrophy. Approximately 66 of patients had vascular risk factors such as hypertension diabetes mellitus hypercholesterolemia coronary artery disease congestive heart failure cardiac arrhythmia obesity and tobacco use. The remainder had no vascular risk factors. The average duration of operation was 8.7 h. The mean decrease of hematocrit was 14.4 between the preoperative and the perioperative period. The mean decrease of systolic blood pressure was 53 mmHg between the preoperative and the perioperative period. The mean intraoperative estimated blood loss was 3.7 L. If no intraoperative hypotension is documented during the surgery then anemia is most likely as evidenced by a mean hemoglobin level that has decreased by 40 to 50 in the perioperative period.228 Neuroimaging of the optic nerves in the perioperative setting can sometimes show the location of the lesion in PION. In a report of a 61-year-old man with bilateral PION after cardiac bypass surgery MRI of the orbits with diffusion-weighted and fluid-attenuated inversion recovery FLAIR sequences can reveal abnormal hyperintensity in both intraorbital optic nerves.245 Bilateral intraorbital optic nerve enhancement was seen on MRI 8 weeks after coronary bypass grafting in a 57-year-old woman who had hypotensive posterior ischemic optic neuropathy.246 Histopathology demonstrates that infarction occurs in the intraorbital portion of the optic nerve in patients with perioperative PION. The central axial portion of the optic nerve is usually infarcted and may be hemorrhagic with sparing of the nerve periphery. Occasionally the infarction may extend to the periphery circumferentially especially in the midorbital section of the optic nerve. The loss of peripheral axons appears to correspond to constricted visual fields.247-249 In the report by Nawa et al.248 on a 67-year-old man with bilateral PION after
