The virus responsible for COVID-19, SARS-CoV-2, is primarily known for causing respiratory illness, but its impact extends beyond the lungs. The eyes are not immune to the infection, which can cause effects ranging from mild surface irritation to severe, vision-threatening complications. The eyes present both a potential entry point for the virus and a target for the immune system’s widespread inflammatory response. Understanding how the infection interacts with the visual system is important for managing symptoms and recognizing when urgent medical attention is required.
Acute Ocular Manifestations of Infection
The most frequent ocular symptom observed during the active phase of a COVID-19 infection is viral conjunctivitis, often called “pink eye.” This inflammation affects the thin membrane covering the white part of the eye and the inner surface of the eyelids. Patients commonly report a gritty sensation, noticeable redness, and swelling. These surface symptoms are reported in a significant minority of confirmed COVID-19 cases, sometimes affecting up to 32% of patients.
Tearing is a common feature, often accompanied by a watery or mucoid discharge. Light sensitivity can also make it difficult to look at bright lights. These surface symptoms frequently develop concurrently with or shortly after the onset of systemic symptoms like fever and cough.
For the majority of individuals, these acute eye problems are self-limiting and resolve within a few days to two weeks, mirroring the typical course of the respiratory infection. Dry eye syndrome, involving burning, stinging, and a foreign body sensation, may also be triggered or worsened by the infection. These acute, inflammatory symptoms are generally not associated with permanent visual impairment.
Vascular and Neurological Visual Changes
A more concerning group of ocular manifestations involves the blood vessels and nerves, usually appearing later in the disease course or during recovery. Systemic inflammation and increased blood clotting risk associated with COVID-19 can lead to blockages in the fine vessels of the retina. These retinal vascular occlusions, such as Central Retinal Artery Occlusion (CRAO) or Central Retinal Vein Occlusion (CRVO), cause sudden, painless vision loss.
These vascular events represent a medical emergency because a blocked retinal artery can lead to irreversible damage within hours. Severe complications are sometimes reported in younger patients who lack traditional risk factors for clotting disorders. Another potential development is Non-Arteritic Ischemic Optic Neuropathy (NAION), which results from inadequate blood flow to the optic nerve.
The virus can also affect the nervous system, leading to neuro-ophthalmic disorders. Optic neuritis, inflammation of the optic nerve, causes pain with eye movement and a decrease in central vision. The infection has also been linked to cranial nerve palsies that control eye movement, resulting in double vision (diplopia).
Biological Mechanisms of Eye Involvement
The ability of SARS-CoV-2 to infect the eyes is linked to the presence of the Angiotensin-Converting Enzyme 2 (ACE2) receptor, which the virus uses as its gateway to enter cells. ACE2 receptors have been identified on the surface of cells in the eye, particularly in the conjunctiva, cornea, and retina.
This distribution allows for two paths of ocular damage: direct infection and indirect systemic injury. Direct viral entry into conjunctival cells triggers the localized inflammation seen in conjunctivitis. Viral RNA has been detected in the tears of some infected individuals, indicating the eye can serve as both a target and a site for viral shedding.
The indirect mechanisms cause the more severe vascular and neurological complications. COVID-19 often triggers a dysregulated immune response, resulting in a systemic inflammatory state described as a cytokine storm. This widespread inflammation can damage the inner lining of blood vessels, contributing to a hypercoagulable state. The resulting clots can then block the small vessels supplying the retina or optic nerve, leading to vision-threatening occlusions.
Managing COVID-Related Eye Symptoms
Management of eye symptoms depends on their severity and location. For mild symptoms associated with acute conjunctivitis, home care is appropriate. Applying cool compresses helps reduce redness and swelling, while over-the-counter artificial tears soothe dryness and the gritty sensation. It is important to avoid rubbing the eyes, as this can worsen irritation and potentially spread the virus.
Certain symptoms warrant immediate consultation with an eye care professional. Any sudden change in vision, such as blurriness, blank spots, or loss of sight, should be treated as an urgent medical situation. Severe, persistent eye pain or the onset of double vision also require prompt medical evaluation to rule out conditions like retinal vascular occlusion or optic neuritis.
An ophthalmologist can perform a comprehensive examination to determine the exact cause of the symptoms and distinguish between mild viral irritation and more serious internal damage. Treatment for severe inflammation or nerve issues may involve specific medications, such as steroid treatments. For vascular occlusions, managing the underlying systemic clotting risk is a major component of the patient’s care plan.