The most significant ocular symptom experienced by those suffering from coronavirus disease 2019 (COVID-19) was sore eyes, according to new research published in BMJ Open Ophthalmology.
Although COVID-19 is primarily a respiratory illness, with the most common symptoms being continuous cough and high temperature, previous research has shown ocular manifestations may present in some individuals with the disease. One study conducted in China found that among children diagnosed with COVID-19, the most common ocular symptoms included conjunctival discharge, eye rubbing, and conjunctival congestion.
Conjunctivitis (pink eye) is also a less common symptom of COVID-19 but is included in the World Health Organization’s list of symptoms. Despite the greater prevalence of more life-threatening outcomes, “The type, frequency, and ocular transmission of the virus must not be ignored, especially as the eye has been recognized as one of the organs through which the virus might enter the body,” researchers wrote.
In addition, there are currently no studies that have conclusively determined the mechanism through with SARS-CoV-2, the virus which causes COVID-19, infects the conjunctiva. According to authors, ocular symptoms are present in between 4% to 31% of those with COVID-19 but may be underreported as they are usually not severe.
To better understand which ocular symptoms are reported most frequently, how these symptoms compare with other COVID-19 symptoms, and how long they last, researchers developed and disseminated an online questionnaire.
The majority of questions were adapted from the Ocular Surface Disease Index (OSDI) and Salisbury Eye Evaluation Questionnaire (SEEQ) that have been used in other COVID-19 studies. Researchers collected anonymous online data between April 16 and July 20, 2020 from a total of 83 participants over the age of 18. All participants had tested positive for COVID-19, as confirmed by a health care provider, and the majority (65%) were female.
“While it is important that ocular symptoms are included in the list of possible COVID-19 symptoms, we argue that sore eyes should replace ‘conjunctivitis’ as it is important to differentiate from symptoms of other types of infections, such as bacterial infections, which manifest as mucous discharge or gritty eyes,” authors wrote.
In addition, the data “agree with the fact that there has been an increase in ‘sore eyes’ as increasing trending Google search term over the past 10 months.”
Future studies ought to investigate whether SARS-CoV-2 can directly infect the conjunctiva and result in ocular symptoms. Researchers also hypothesize the cornea may be the site of infection. “In cornea limbal stem cells from healthy human participants and murine cornea, high mRNA expression of ACE2 [angiotensin converting enzyme 2] and TMPRSS2 has been identified, suggesting that SARS-CoV-2 may infect the ocular surface via the cornea using the traditional ACE2-TMPRSS2-mediated mechanism of cell entry.” This type of infection may also enable the spread of the virus through the nose, lungs, bloodstream and nervous system.
In the current study, researchers did not collect data on prior eye disease or on self-reported vision loss, potentially marking a limitation. Because the study was conducted online, responses may have been biased toward digitally literate patients. Additional studies geared toward including older patients with COVID-19 ocular manifestations are thus warranted.
Pardhan S, Vaughan M, Zhang J, Smith L, and Chichger H. Sore eyes as the most significant ocular symptoms experienced by people with COVID-19: a comparison between pre-COVID-19 and during COVID-19 states. BMJ Open Ophthalmol. Published online November 30, 2020. doi:10.1136/bmjophth-2020-000632