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Background: Growing evidence suggests an association between the infection from the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and eye disorders. The aim of this review was to analyze the clinical presentation and diagnostic features of acute macular neuroretinopathy (AMN) and paracentral acute middle maculopathy (PAMM) associated with COVID-19 infection. The features are then compared with previous reports regarding these retinal disorders, to recognize possible specific characteristics and to assess the role of multimodal ophthalmic imaging. Summary: A literature search was performed by consulting PubMed, Scopus, and Embase. The following terms were searched: "(COVID-19 OR SARS-CoV-2 OR coronavirus) AND ([acute macular neuroretinopathy] OR [paracentral acute middle maculopathy])." Inclusion criteria were as follows: (1) publication date from January 31, 2020 to January 31, 2022; (2) English language; (3) original research or case report; (4) free full-text availability.Optical coherence tomography (OCT) findings in AMN patients were hyper-reflectivity (HR) of the outer plexiform layer, of the outer nuclear layer, and ellipsoid or interdigitation zones (EZ and IZ, respectively) disruption. In most cases, the presence of HR and EZ/IZ abnormalities resulted combined. When performed, OCT angiography (OCTA) identified attenuation of signal of the deep capillary plexus (DCP). The most common OCT finding in PAMM was an alteration of the inner nuclear layer, associated with other areas of HR, while no signs of EZ/IZ disruption were detected. When performed, OCTA showed the attenuation of signal of both the DCP and the superficial capillary plexus. Key Messages: In this review, we reported a case series of AMN and PAMM in patients with a previous or concomitant infection from SARS-CoV-2. The microvascular changes in these cases are highlighted by the OCTA scans. Even if we are far from the determination of a direct link between COVID-19 and these retinal disorders, we could hypothesize that the vascular alterations associated with SARS-CoV-2 infection could be a possible risk factor for both AMN and PAMM. [ABSTRACT FROM AUTHOR]

We discuss the case of a 22-year-old man who presented with paraesthesia, reduced sensation and weakness in his limbs. Examination was in keeping with a myeloneuropathy. Initial investigations including vitamin B12 were unremarkable but magnetic resonance imaging of the spinal cord showed subacute combined degeneration. The patient reported heavy recreational use of nitrous oxide, which can cause functional deficiency of vitamin B12 with neurological sequelae. A diagnosis of functional vitamin B12 deficiency was made and confirmed by an elevated methylmalonic acid level. The patient received intramuscular hydroxocobalamin and made a good recovery following rehabilitation. Nitrous oxide use is prevalent and can have significant health effects. Many adverse effects are mediated through inactivation of vitamin B12 and can be detected by elevated homocysteine and methylmalonic acid levels. Early identification and prompt treatment are important to support neurological recovery. [ABSTRACT FROM AUTHOR]