The emergence of COVID-19, first identified in Wuhan, China, marked the advent of a global health crisis. The World Health Organization promptly identified the causative agent as the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), responsible for causing not only severe respiratory issues but also a spectrum of other medical complications.
Among these, COVID-19 has been noted for its potential to induce hypercoagulability leading to thrombus formation and a range of pro-inflammatory conditions. This aspect of the disease has been closely linked with elevated D-dimer levels and the presence of antiphospholipid antibodies, factors significantly contributing to its complexity and severity.
Unraveling the Mysteries of Acute Macular Neuroretinopathy
Parallel to the systemic impact of COVID-19, there’s an increased interest in its ocular implications, particularly in the context of acute macular neuroretinopathy (AMN). AMN, a rare retinal condition, primarily affects the outer layers of the retina. Its diagnosis is predominantly reliant on multimodal imaging techniques, with fundus photographs revealing characteristic petaloid-shaped dark red lesions near the central macula.
The pathophysiology of AMN remains partially understood, but it’s believed to stem from vascular dysregulation affecting the retinal plexus. This disease, while usually self-limiting, can result in persistent thinning of the outer nuclear layer. AMN has been linked to various vascular and systemic factors, including blood pressure anomalies and infectious diseases like dengue and influenza.
The Beijing Experience: A Case Study on AMN during the COVID-19 Pandemic
In 2022, Beijing Tongren Hospital reported a noticeable increase in AMN cases during the peak of the COVID-19 pandemic. This study delves into 11 patients who developed AMN following a COVID-19 infection, aiming to explore the patterns and possible mechanisms linking AMN with the viral infection.
This retrospective observational study, adhering to the Helsinki Declaration principles, included patients diagnosed with AMN post COVID-19 infection. The study period spanned from December 1, 2022, to February 28, 2023. The inclusion criteria were strictly defined, encompassing diagnostic markers for AMN and a confirmed SARS-CoV-2 infection within a month preceding the onset of AMN symptoms.
Comprehensive Data Collection and Analysis
A thorough collection of demographic and clinical data was undertaken. This included general health information, ocular examination findings, and detailed imaging studies. The medical records provided a comprehensive overview of each case, which were analyzed using statistical tools for a clear understanding of the trends and correlations.
Discussion: The Intricacies of AMN in the Context of COVID-19
Diverse Ocular Manifestations of COVID-19
The COVID-19 pandemic, caused by the novel SARS-CoV-2 virus, has presented a multitude of extrapulmonary manifestations, significantly impacting ocular health. Ophthalmologists have observed a wide range of ocular issues linked with COVID-19, from anterior segment complications like conjunctivitis and uveitis to more severe conditions affecting the retina and optic nerve, such as retinitis and optic neuritis. Particularly noteworthy are the retinal lesions associated with COVID-19, characterized by ischemic events including retinal hemorrhages and cotton-wool spots.
Acute Macular Neuroretinopathy (AMN) Post COVID-19
AMN, while rare, has emerged as a significant retinal disease in the wake of COVID-19. Historically associated with diseases like dengue and influenza, its occurrence post-COVID-19 infection, as observed in our series of 11 patients, indicates a potential direct link with the virus. These patients developed AMN shortly after contracting COVID-19, suggesting an intertwining of the disease’s pathogenesis with AMN onset.
Demographics and Symptomatology
The majority of AMN cases post-COVID-19 in this series were young females, averaging 33.8 years of age, presenting with symptoms such as scotomas, visual acuity decline, and blurring. While most patients experienced eventual visual acuity recovery, scotomas often persisted, underscoring the long-term impact of AMN. Cases in literature, including those by Virgo, Ferkova, and Aidar, further corroborate these findings, highlighting varied recovery timelines and persistent visual deficits.
Imaging Insights: SD-OCT and NIR
Through this study, the utility of spectral domain optical coherence tomography (SD-OCT) and near-infrared (NIR) imaging in diagnosing and monitoring AMN becomes evident. SD-OCT proved particularly sensitive in identifying structural anomalies such as ONL hyperreflectivity and disruption in the ellipsoid zone (EZ). These imaging modalities, even when clinical examinations showed no abnormalities, were crucial in detecting and tracking the progression of AMN.
Vascular Contributions and Pathogenesis
The pathogenesis of AMN, while still not fully understood, seems to be closely tied to vascular factors. Studies, including those utilizing OCT angiography (OCTA), have suggested reduced perfusion in the deep macular capillary plexus and choroidal vasculature in AMN patients. This study’s observations of reduced blood flow in these areas post-COVID-19 infection further support the vascular hypothesis in AMN development. The role of ACE2 receptors in COVID-19 and its potential impact on retinal cells highlights the complex interplay of viral infection and ocular health.
Limitations and Further Research
This study, however, is not without its limitations. The primary constraint is the inability to definitively link AMN to COVID-19 infection, largely due to the retrospective nature of the study and the small sample size. Additionally, the absence of intraocular sampling for inflammatory markers limits the depth of our understanding. A longer follow-up period is also necessary for a more comprehensive view of the disease’s progression and its correlation with systemic factors.
In conclusion, this case series underscores that COVID-19-related AMN primarily affects young women and can lead to long-term visual impairments. The use of multimodal diagnostic imaging, particularly SD-OCT and OCTA, has been instrumental in characterizing AMN and its progression. For patients experiencing visual issues during COVID-19, a thorough retinal evaluation is imperative for early detection of AMN. Despite the advancements made, the field still requires extensive research to fully understand the retinal pathophysiological changes induced by SARS-CoV-2.
reference link : https://bmcophthalmol.biomedcentral.com/articles/10.1186/s12886-024-03283-2