Eye floaters are small specks, dots, or cobweb-like shapes that drift across a person’s field of vision. Mounting clinical evidence and patient reports suggest a connection between COVID-19 infection and the appearance or significant increase of these floaters. The systemic nature of the SARS-CoV-2 virus, which affects multiple organs, appears to extend to the delicate structures of the eye. Researchers are investigating the underlying biological changes that link this respiratory illness to visual disturbances.
Understanding Eye Floaters
Floaters are shadows cast onto the retina, the light-sensitive tissue at the back of the eye. The debris causing these shadows is suspended within the vitreous humor, a transparent, gel-like substance that fills the space between the lens and the retina. As light enters the eye, these particles block a tiny portion of it, making them visible.
The most common cause of floaters is the natural aging process, known as vitreous syneresis. Over time, the vitreous gel liquefies and shrinks, allowing microscopic collagen fibers and cellular debris to clump together and float. While floaters are generally harmless, their sudden appearance or a change in their number or size can sometimes signal a more serious underlying issue. Nearsightedness (myopia) can also cause floaters to appear earlier due to the elongated shape of the eye, which stresses the vitreous.
The Recognized Link Between COVID-19 and Ocular Changes
Clinical observations consistently document that new or worsening floaters are among the ocular symptoms reported by patients during or following a COVID-19 infection. Studies indicate that floaters, blurred vision, red eyes, and increased light sensitivity occur in a notable percentage of individuals recovering from the virus. This suggests a clear ophthalmic manifestation of a systemic disease.
The virus’s impact is not limited to the eye surface, where it can cause conjunctivitis, but often extends to the posterior segment. This region includes the vitreous and the retina, where floaters originate. The SARS-CoV-2 virus uses the angiotensin-converting enzyme 2 (ACE2) receptor to enter cells. The presence of this receptor on various ocular tissues provides a plausible route for the virus to directly or indirectly affect the eye.
Reports highlight conditions like uveitis, an inflammation inside the eye, which can manifest as floaters and blurred vision. Doctors have also observed other vitreoretinal abnormalities, including central retinal vein occlusion, in COVID-19 patients. These findings confirm that the infection can trigger reactions that compromise the clarity of the vitreous humor.
Biological Mechanisms Driving Post-COVID Floaters
The appearance of floaters post-COVID is often a consequence of the body’s inflammatory response and the virus’s effect on blood vessels. A proposed mechanism involves systemic inflammation, including the excessive production of inflammatory signaling molecules known as a “cytokine storm.” This widespread inflammation can breach the delicate blood-retinal barrier, leading to inflammatory cells and debris entering the vitreous, which are perceived as floaters.
The virus also causes microvascular damage throughout the body. By binding to ACE2 receptors on vascular endothelial cells, SARS-CoV-2 promotes hypercoagulability and thrombosis. This can result in small blockages or leaks in the blood vessels of the retina, potentially causing minute hemorrhages. These hemorrhages leave behind cellular remnants or blood components in the vitreous, contributing to floaters.
Another likely cause is the accelerated development of Posterior Vitreous Detachment (PVD). PVD occurs when the shrinking vitreous gel pulls away from the retina. This process normally takes time but may be hastened by the severe physiological stress of a major illness like COVID-19. This detachment often releases a large, sudden ring-shaped floater or a shower of smaller floaters as the vitreous collapses. The inflammatory response may also upregulate collagen-degrading enzymes in the vitreous, contributing to the speed of liquefaction and collapse.
Recognizing Serious Symptoms and When to Seek Medical Attention
While most floaters, even those linked to a recent illness, are generally benign, they can occasionally signal a sight-threatening emergency. It is important to know the “red flag” symptoms that require immediate evaluation by an eye care professional. A sudden, significant shower of new floaters, especially if they appear darker than normal, warrants urgent attention to rule out a retinal tear or detachment.
Flashes of light, known as photopsia, are another serious warning sign, often described as lightning streaks or camera flashes. These flashes suggest the vitreous is tugging on the retina, which can lead to a tear. The appearance of a dark curtain or shadow that obstructs peripheral or central vision is a definite symptom of a detached retina and constitutes a medical emergency. If these sudden, severe symptoms occur, prompt evaluation is necessary, as a detached retina can lead to permanent vision loss if not treated quickly.