Acute Bilateral Vision Loss in Pregnancy: A Case of Posterior Reversible Encephalopathy Syndrome.

Posterior reversible encephalopathy syndrome (PRES) is a clinicoradiological entity characterized by headache, seizures, altered consciousness, and visual disturbances, with preeclampsia and eclampsia among its most common triggers. Although visual symptoms occur in roughly one-third of cases, acute cortical blindness as the predominant presenting feature in the absence of significant hypertension is uncommon and diagnostically challenging. We report a 27-year-old woman (gravida 2, abortion 1) at 36 weeks of gestation who presented with a one-day history of headache, a generalized tonic-clonic seizure, and sudden bilateral vision loss, with a blood pressure of 110/60 mmHg. Ophthalmological examination revealed no perception of light bilaterally with preserved pupillary reflexes and a normal fundus, localizing the deficit to the visual cortex. Investigations demonstrated mild anemia, thrombocytopenia, prolonged activated partial thromboplastin time (aPTT), and proteinuria. Magnetic resonance imaging revealed bilateral T2/fluid-attenuated inversion recovery (FLAIR) hyperintensities in the occipital lobes involving the primary visual cortex, confirming PRES. An emergency lower segment cesarean section was performed under general anesthesia for fetal distress. Postoperative autoimmune workup revealed strongly positive anti-nRNP and anti-Ro antibodies with a positive lupus anticoagulant. Management included the Zuspan magnesium sulfate regimen, hydroxychloroquine, aspirin, and bridging anticoagulation with enoxaparin to warfarin. Complete visual recovery was achieved by postoperative day 3. This case illustrates that acute bilateral cortical blindness may be a manifestation of PRES in eclampsia even without marked hypertension, consistent with the endothelial dysfunction model of pathogenesis. Timely multidisciplinary recognition and intervention facilitated complete recovery.