COVID-19, caused by the SARS-CoV-2 virus, is primarily known for its respiratory symptoms, but its effects extend beyond the lungs. Many people who contract the infection experience symptoms involving the eyes, confirming that ocular involvement is a recognized part of the disease presentation. Researchers have documented a spectrum of complications, ranging from temporary surface irritation to more serious vision-threatening conditions.
Acute Ocular Manifestations
The most frequent eye-related issue observed during the acute phase of a COVID-19 infection is viral conjunctivitis, commonly known as pink eye. This surface inflammation affects the conjunctiva, the clear membrane covering the white part of the eye and the inner surface of the eyelids. Symptoms often include noticeable redness, a gritty foreign body sensation, increased tearing (epiphora), and sensitivity to light (photophobia). Discharge, often mucoid or watery, accompanies the irritation. These signs typically appear concurrently with or shortly after the onset of systemic COVID-19 symptoms. For the majority of people, these surface-level symptoms are temporary and tend to clear up as the main respiratory illness resolves, usually within a few days to two weeks.
Mechanisms of Viral Impact on the Eye
The ability of SARS-CoV-2 to affect the eyes stems from the presence of specific protein receptors on the ocular surface. The virus uses the Angiotensin-Converting Enzyme 2 (ACE2) receptor, along with the co-receptor TMPRSS2, to enter human cells. These receptors are expressed on the epithelial cells of the conjunctiva and the cornea, providing a direct access point for the virus. This pathway suggests the virus can directly infect eye tissue, leading to acute symptoms like conjunctivitis.
Beyond direct infection, systemic inflammation is a major contributor to eye issues. COVID-19 triggers an intense immune response that generates widespread inflammation and a hypercoagulable state throughout the body. This systemic reaction can damage the delicate blood vessels and nerves of the eye, even if the virus does not directly infect those deeper structures.
Vision Changes Related to Systemic Complications
While conjunctivitis is the most common manifestation, the systemic effects of the infection can lead to more serious, vision-threatening complications. A significant concern involves vascular problems, specifically the blockage of blood flow to the retina. Retinal artery occlusion (RAO) or retinal vein occlusion (RVO) occur when blood clots, formed due to the virus-induced hypercoagulable state, travel to the eye’s vessels.
A central retinal artery occlusion (CRAO) causes sudden, painless, and severe loss of vision in the affected eye, constituting an ocular emergency. Inflammation can also affect the optic nerve, leading to optic neuritis. This involves the swelling and damage of the nerve that transmits visual information to the brain, resulting in blurred vision, pain with eye movement, and altered color perception.
Less common are neuro-ophthalmic issues such as Non-Arteritic Ischemic Optic Neuropathy (NAION), which results from insufficient blood flow to the optic nerve head. These severe complications are linked to the endothelial dysfunction and inflammation that persist even after the initial respiratory symptoms have subsided. Studies have shown these retinal and optic nerve events can occur months after an initial, even mild, COVID-19 infection.
Clinical Management and When to Seek Help
For the common presentation of viral conjunctivitis related to COVID-19, treatment focuses on supportive care to relieve symptoms. This includes using artificial tears to soothe dryness and irritation, and applying cool compresses to reduce swelling and redness. Patients should also avoid wearing contact lenses until all symptoms have fully resolved and practice meticulous hand hygiene to prevent viral spread.
It is important to consult an eye care professional, such as an optometrist or ophthalmologist, if eye symptoms are severe, persist beyond two weeks, or are accompanied by a sudden change in vision. Immediate medical attention is necessary for specific urgent symptoms, as these severe conditions may necessitate anti-inflammatory treatments such as steroids.
Urgent symptoms requiring immediate intervention include:
- Sudden, painless loss of vision, which may signal a retinal vascular occlusion.
- Severe eye pain.
- Rapid onset of blurred vision, which can indicate optic neuritis or intraocular inflammation like uveitis.