The virus that causes COVID-19, SARS-CoV-2, can affect eyesight, ranging from mild, temporary irritation to rare, severe complications that threaten vision. While the respiratory system is the primary target, the ocular surface and internal structures of the eye are also susceptible to direct viral action or systemic effects. Most acute eye issues are surface-level and resolve quickly, but the potential for serious vascular and neurological complications exists. Understanding how the infection impacts the visual system involves looking at both the common, immediate symptoms and the less frequent, but more concerning, internal damage.
Common Ocular Symptoms During Acute Infection
The most frequent eye manifestation during active COVID-19 infection is viral conjunctivitis, commonly known as pink eye, affecting about 1 in 10 patients. This involves inflammation of the conjunctiva, the membrane covering the white part of the eye and inner eyelids. Symptoms often include eye redness, excessive tearing (epiphora), a gritty sensation, and sometimes a watery or yellowish discharge. Patients may also experience photophobia (increased sensitivity to light) and general eye pain. These irritations are usually mild and self-limiting, typically clearing up within a few days to two weeks without causing lasting vision damage.
Potential Sight-Threatening Complications
Less common but serious complications involve the internal vascular or neural structures of the eye. Systemic inflammation caused by the virus can lead to hypercoagulability, increasing the blood’s tendency to clot. These blood clots can travel and lodge in the eye’s small vessels, causing sudden vision loss.
A retinal artery occlusion, often referred to as an “eye stroke,” occurs when a clot blocks the main artery supplying the retina, leading to rapid cell death. Conversely, a retinal vein occlusion blocks drainage, causing pressure buildup, bleeding, and swelling. Another rare neurological complication is optic neuritis, which is inflammation of the optic nerve, potentially causing temporary or permanent vision impairment.
Biological Pathways of Ocular Involvement
The mechanisms behind ocular involvement stem from both direct viral presence and the body’s inflammatory response. SARS-CoV-2 gains entry into human cells by binding to the angiotensin-converting enzyme 2 (ACE2) receptor. This receptor is present on the epithelial cells of the conjunctiva, providing a pathway for the virus to cause local infection and conjunctivitis.
The virus’s systemic effects drive the more severe complications. Infection can trigger a “cytokine storm,” an excessive release of inflammatory molecules that damage delicate blood vessels throughout the body, including those in the retina. This widespread inflammation, known as endotheliitis, contributes to the hypercoagulable state by activating platelets and coagulation pathways. The resulting microvascular damage and increased clotting risk are what lead to potentially blinding events. Furthermore, inflammation can breach the blood-retinal barrier, which normally protects the retina from pathogens, allowing the inflammatory process to affect the posterior segment of the eye, leading to conditions such as uveitis.
Persistent Visual Issues After Recovery
A distinct set of visual symptoms can persist or newly appear long after the acute infection has cleared, becoming a component of Long COVID. One frequently reported issue is chronic dry eye syndrome, which causes persistent discomfort, burning, and a gritty feeling due to changes in tear film quality or production. This chronic dryness can make the eyes feel continually strained.
Other persistent symptoms often involve neurological pathways, reflecting the virus’s impact on the brain-eye circuit. Patients may report ongoing photophobia, where bright light remains painful, and visual fatigue, which is a reduced ability to sustain visual tasks like reading or screen time. Some individuals also experience blurriness, difficulty focusing, or double vision (diplopia), which can be related to issues with eye muscle coordination or general neurological dysfunction. If any visual symptoms continue long after recovery, consulting an eye care specialist is important to rule out progressive damage and manage the chronic symptoms.