Experimental Study Links COVID-19 Infection to Age-Related Blindness Risk

A recent experimental study in mice has revealed that SARS-CoV-2 infection can damage the retina, potentially leading to long-term vision impairment. The findings, published in PNAS Nexus, suggest that COVID-19 may play a role in age-related macular degeneration (AMD) by triggering inflammation and disrupting retinal function.

COVID-19 and Its Impact on the Central Nervous System

Post-acute sequelae of COVID-19 include a range of neurocognitive symptoms, highlighting the virus’s ability to affect the central nervous system (CNS). Since the eyes are an extension of the CNS, researchers have been investigating how SARS-CoV-2 might impact ocular health.

In this study, David Williams and Nan Hultgren infected transgenic mice expressing human ACE2 receptors with SARS-CoV-2. Five days later, they examined the retinas and lungs of these mice to determine the virus’s impact.

SARS-CoV-2 Infects Retinal Pigment Epithelium

The researchers found SARS-CoV-2 present in the retinal pigment epithelium (RPE)—a critical layer of cells responsible for supporting photoreceptors and maintaining the blood-retina barrier. Interestingly, there was no correlation between viral load in the retina and lungs, indicating that severe respiratory symptoms are not required for significant retinal infection.

Further experiments in cultured human RPE cells confirmed that the virus’s toxic proteins altered cell shape, making them more vulnerable to oxidative stress. These changes compromised retinal integrity, impairing the cells’ ability to recycle photoreceptor components and maintain proper function.

Inflammation and Increased AMD Risk

Beyond structural damage, SARS-CoV-2 infection triggered widespread inflammation in the retinal pigment epithelium, including:

       • Complement system activation

       • Elevated production and secretion of inflammatory cytokines

These inflammatory responses are major risk factors for age-related macular degeneration, suggesting that COVID-19 infection could accelerate the onset and progression of age-related blindness.

Potential Long-Term Implications

According to the study’s authors, the ocular effects of COVID-19 require further investigation, particularly in relation to AMD and other retinal diseases. Understanding this connection may help identify new therapeutic targets to mitigate vision loss associated with post-COVID complications.

Reference:

https://academic.oup.com/pnasnexus/article/3/12/pgae500/7911947