COVID-19 Tied to Rise in Acute Macular Neuroretinopathy

A recent Chinese study highlights a rise in cases of acute macular neuroretinopathy (AMN) and related retinal conditions coinciding with the COVID-19 outbreak. Dr. Xiaojia Song, MD, from Beijing Tongren Eye Center and Qilu Hospital of Shandong University, led the investigation, which sheds light on the association between COVID-19 and rare retinal conditions.

What is Acute Macular Neuroretinopathy (AMN)?

AMN is a rare retinal condition characterized by dark reddish, wedge-shaped lesions in the macula and impairment of the retinal deep capillary plexus, suggesting ischemia as a possible cause. Though its exact etiology remains unclear, AMN is increasingly recognized as a possible ocular manifestation of COVID-19.

Rise in AMN Cases Following COVID-19 Surge in China

Following the end of China’s zero-COVID policy in late 2022, a significant outbreak of COVID-19 occurred, particularly with the SARS-CoV-2 Omicron variant, and was accompanied by an increase in AMN cases. Researchers noted that although AMN has been reported after COVID-19 in individual cases, the large surge within such a short period was unprecedented.

COVID-19’s Link to Retinal Vasculopathies and Systemic Impacts

Severe COVID-19 infections are known to cause inflammatory responses and hypercoagulation, potentially leading to systemic conditions like pulmonary embolism, ischemic stroke, and myocardial infarction. The virus has also been associated with retinal vasculopathies such as AMN, paracentral acute middle maculopathy (PAMM), and Purtscher-like retinopathy, indicating potential links between COVID-19 and retinal ischemic conditions.

Study Design and Methods

This prospective observational study in northern China recruited patients diagnosed with AMN who had confirmed SARS-CoV-2 Omicron infections. Researchers performed comprehensive retinal imaging and visual function assessments, including:

• Color fundus photography

• Near-infrared imaging

• Swept-source optical coherence tomography (SS-OCT)

• OCT angiography (OCTA)

• Humphrey perimetry

Key Findings from the Study

The study included 33 patients (12 men and 21 women), with 87.88% presenting with bilateral symptoms. Key findings included:

• Rapid Onset: Ocular symptoms appeared on average two days after fever onset.

• Retinal Alterations: Patients exhibited typical AMN-related outer retinal changes, with additional findings such as intraretinal hemorrhage (8.06%), cotton wool spots (9.68%), and paracentral PAMM (8.06%).

• Unique Inner Retinal Changes: Smaller retinal inner nuclear layer hyperreflective speckles (RIHS) were noted in 41.94% of cases, distinguishing AMN-related changes from typical PAMM findings.

• Vessel Signal Voids: OCTA showed voids in the superficial (11.54%), intermediate (82.69%), deep capillary plexus (98.08%), and choriocapillaris (19.23%).

• Visual Field Deficits: Humphrey perimetry revealed central, paracentral, and peripheral scotomas, which were mapped and confirmed by OCTA as perfusion defects.

Study Conclusions: COVID-19’s Role in Ocular and Systemic Microcirculation Disruption

The study concluded that AMN cases closely followed the surge of Omicron infections in China. Patients often showed bilateral retinal changes with symptoms linked directly to COVID-19. Notable findings included:

• Choriocapillaris and Inner Retinal Changes: Widespread inner retinal damage and choriocapillaris perfusion deficits were prominent.

• Potential Biomarkers: OCTA findings suggested perfusion deficits, supporting the possibility of systemic microcirculation dysregulation in COVID-19.

The researchers highlighted that the presence of RIHS, seen only in AMN, points to a distinct pathogenesis compared to PAMM, where flow insufficiency may play a larger role. These findings suggest that OCTA may serve as a diagnostic tool and potential biomarker for widespread ischemia in COVID-19.

Future Implications and Research

The study emphasizes the need for further research to understand the mechanisms by which the SARS-CoV-2 Omicron variant may contribute to retinal and systemic vascular conditions. Expanding knowledge in this area could help identify early indicators of ischemic damage in COVID-19 patients and improve approaches to managing COVID-19-related retinopathy.

References:

Song X, Yu Y, Zhou H, et al. Acute macular neuroretinopathy associated with covid-19 pandemic: a real-world observation study. Asia Pac J Ophthalmol. 2024;13; https://doi.org/10.1016/j.apjo.2024.100103

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