Ophthalmic Manifestations of COVID-19

Introduction and Historical Perspectives

In late December 2019, an ophthalmologist named Li Wenliang sent a message to a group of fellow physicians in Wuhan, China, warning them of an emerging respiratory illness that he thought bore resemblance to severe acute respiratory syndrome (SARS). Weeks later, after local authorities admonished him for “spreading rumors,” Dr. Li contracted the virus from one of his glaucoma patients and passed away.

Ophthalmological manifestations of members of the Coronaviridae family were documented long before SARS-CoV-2 surfaced in humans. In the mid-20th century, a murine coronavirus was demonstrated to infect central nervous system cells and was later shown to cause a biphasic infection of the mouse retina characterized by early vasculitis and subsequent retinal degeneration. Later, with the first outbreak of the SARS pandemic in 2003, it was demonstrated that SARS-CoV-1 could cause conjunctivitis in humans ^, and was detectable in tear samples. In fact, the first diagnosis of a new SARS-CoV-1 strain was made in a 7-month-old child with conjunctivitis. It was also hypothesized that transmission of SARS-CoV-1 could occur through the ocular surface, because contact with SARS patient secretions without eye protection was an independent risk factor for transmission of the virus.

Since Dr. Li’s death, ophthalmologists have remained on the front lines of the COVID-19 pandemic and will continue to play an important role in prevention and detection of SARS-CoV-2 in the months and years to come. The physical examination is a critical component of an ophthalmology visit, and the close proximity necessitated by the slit-lamp examination is well within the range of droplets expelled by conversation and normal breathing that may harbor the virus. ^, Therefore it is essential that all health care workers who care for patients with eye conditions be prepared to recognize the role that the ocular surface plays in transmission of the virus, the ophthalmic manifestations of COVID-19, and the therapeutic interventions.

Role of the Eye in Transmission and Prevention

The surface of the eye is an important route of transmission for many pathogens, and coronaviruses are no exception. Surface proteins angiotensin-converting enzyme-2 (ACE2) and transmembrane protease serine 2 must be present for SARS-CoV-2 to invade human cells, and both receptors have been shown to be consistently expressed on the cornea, pointing to a possible route of ocular infection. ACE2 expression also has been demonstrated on the conjunctiva and in the aqueous humor.

In addition to being a potential site of inoculation, the eye also may play a role in viral shedding. Studies of a feline coronavirus have demonstrated that the offspring of infected cats have detectable live coronavirus on the conjunctiva, suggesting that ocular secretions are potentially infectious. Studies conducted in China early in the pandemic showed that a small number of patients had tear samples that were positive for SARS-CoV-2 antigens. ^, In a more recent study conducted in Italy, SARS-CoV-2 RNA was detected on the surface of the eye in 52 of 91 patients with COVID-19.

Lending further credence to the idea that SARS-CoV-2 transmission may occur through the ocular surface, a study conducted in China found that patients who wore eyeglasses daily may be less likely to contract the virus. This finding prompted many health care institutions to require eye protection for all employees who encounter patients during the pandemic. The decreased susceptibility to infection in eyeglass wearers suggests that the barrier provided by the glasses prevents contact of the ocular surface with droplets that may be expelled by patients as they cough, speak, or breathe. Alternatively, glasses could provide a deterrent to inadvertent touching of the eyes with hands that are contaminated with viral particles. Contact lens wearers are not afforded the same protection, but they also are not at any increased risk for infection, despite regularly touching their eyes to place and remove contact lenses.

Ocular Manifestations