Background <p>Common causes of cortical blindness are usually congenital or acquired neurological disorders, rather than hyperammonemia occurring secondary to renal or hepatic diseases. Hyperammonemia is an extremely rare cause of cortical blindness. In hyperammonemia, also common presentations are altered sensorium, seizures, etc., and not cortical blindness. The diagnosis of cortical blindness in neurologically intact patients requires a high index of suspicion; otherwise, diagnoses are easily missed.</p> <p>Case presentation.</p> <p>Herein, we present a case report of a 32-year-old male who developed complete loss of vision without alteration in sensorium. The patient was a known case of chronic kidney disease on hemodialysis and liver cirrhosis secondary to hepatitis C infection, but there were no features of liver failure at the time of presentation. Secondary to sepsis, the patient’s ammonia level increased markedly (216&#xa0;mg/dL) and developed hepatic encephalopathy, but its initial presentation was of vision loss rather than changes in sensorium.</p> Conclusion <p>This case highlights that cortical blindness can precede classic encephalopathy in hyperammonemia, necessitating early detection and ammonia-lowering therapy. An aggressive hemodialysis caused full recovery of vision in this patient.</p>