BACKGROUND: Anterior Ischemic Optic Neuropathy (AION) is caused by poor circulation to the blood vessels that supply the anterior optic nerve and is typically seen in patients with cardiovascular diseases such as hypertension, diabetes, and arterio/atherosclerosis. Nocturnal arterial hypotension is usually thought to be the culprit that causes a physiologic fall in blood pressure during sleep, allowing the perfusion pressure of the optic nerve vessels to drop. This fall in blood pressure may be exacerbated if pressure reducing medication is taken at night. Our patient presented with a case of AION where the fall in perfusion pressure to the optic nerve was caused by cardiovascular shock.
CASE REPORT(S): A 49 year old black male presented to the Codman Square Eye Clinic with complaints of sudden vision loss inferiorly in his right eye. He noticed this vision loss while he was hospitalized with severe GI bleeding 2 weeks prior. At this time, his blood pressure dropped to 80/40 and he required a four unit transfusion. He also had a history of diabetes and hypercholesterolemia for which he was being treated with Insulin and Lipitor. He denied any allergies. Best corrected visual acuity was 20/20 OD and OS. EOM movements were full and smooth, and color vision testing was normal OD/OS. Pupillary testing revealed a +RAPD OD. Anterior segment evaluation was unremarkable OD/OS. IOP was 14mmHg OD/OS. Posterior pole evaluation revealed superior pallor of the optic nerve OD. Also noted were cotton wool spots in the inferior arcade and exudates temporal to the macula OD. The OS presented only with a couple pinpoint hemorrhages in the posterior pole. Humphry visual field testing revealed a dense inferior altitudinal defect in the right eye while the left eye was within normal limits. Follow up evaluation 2 months later showed the visual field to be stable.
CONCLUSIONS: This is a case of shock-induced ischemic optic neuropathy. Although the mechanism is the same as the more classical presentation of non-arteritic AION, its etiology remains a distinct clinical entity.