Lights Off, Lights On: Amaurosis Fugax in Polycythemia.

There are many causes of amaurosis fugax, including polycythemia. Polycythemia is associated with elevated hematocrit levels and hyperviscosity, which can lead to ocular manifestations. We report a polycythemia patient with amaurosis fugax, who had resolution of ocular symptoms following venesection. A 29-year-old gentleman presented with a six-month history of episodic bilateral transient loss of vision (amaurosis fugax), followed by slow recovery back to normal after 15-20 minutes. The symptoms worsened with fatigue. He also had an unsteady gait for the preceding one year. Ocular examination was unremarkable. His visual acuity was 20/20 OU. Neurological examination revealed gait ataxia and dysdiadochokinesia. Computed tomography (CT) angiogram showed an old cerebellar infarct. Blood investigations showed persistent elevated hemoglobin and hematocrit with positive JAK-2 V617F mutation. Infective and connective tissue workups were all negative. A diagnosis of polycythemia was made by the haematology team. In addition to oral aspirin given by the neurology team, he underwent venesection with improvement in ocular symptoms following each episode of venesection. The frequency of amaurosis fugax reduced from 2-3 episodes a week to once a month, then resolved completely after five venesections. Systemically, his cerebellar symptoms also resolved and there were no neurological deficits. Polycythemia is a rare disease that can cause amaurosis fugax and thrombotic events in young patients. Better knowledge and accurate diagnosis are important, as early treatment may improve the symptoms and long-term morbidity.

Recurrent Optic Neuritis in Paediatric Anti-N-Methyl-D-Aspartate Receptor (Anti-NMDAR) Encephalitis: Case Report and Literature Review.

Optic neuritis associated with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis poses a novel challenge and is recognised as being part of overlapping antibody-associated demyelinating syndromes. We report a case of a 10-year-old girl who first presented with anti-NMDAR encephalitis and later developed four episodes of left optic neuritis. Blurring of vision, pain on eye movement, and headache were the striking features in all episodes of optic neuritis. For each recurrent episode of optic neuritis she was treated with intravenous methylprednisolone, following which visual acuity, colour vision, and visual field improved to normal. Neuroimaging was unremarkable. Myelin oligodendrocyte glycoprotein and aquaporin-4 antibody tests were negative. She developed a relapse of anti-NMDAR encephalitis after recurrent episodes of optic neuritis despite being on azathioprine. Intravenous immunoglobulin and cycles of cyclophosphamide were started, and she has been free from optic neuritis and encephalitis for more than one year since. Optic neuritis and anti-NMDAR encephalitis are reversible with intensive immunotherapy. Early and accurate diagnosis can lead to better management of this condition.

Atypical Presentation of Idiopathic Bilateral Optic Perineuritis in a Young Patient.

A previously healthy 27-year-old Malay male presented with acute onset of painless, severe blurring of vision in his right eye. It was associated with headache and vomiting for the past week. Relative afferent pupillary defect was present in the right eye, with reduced optic nerve function. Patient also had bilateral generalised optic disc swelling, splinter haemorrhages, and tortuous vessels. Initial examination was suggestive of either optic neuritis or raised intracranial pressure. Typical features of bilateral optic perineuritis (OPN) such as tram track and doughnut sign were observed on magnetic resonance imaging. Connective tissue and infective screening were negative. He was diagnosed with bilateral optic perineuritis and treated with high dose intravenous corticosteroids followed by a three-month course of oral steroids. His vision and optic nerve function recovered to baseline levels.