Timothy C. Hain, MD Page last modified: May 11, 2020
The pandemic of the coronavirus disease of 2019 (covid19) has posed a number of challenges for patients and for physicians. Its repercussions are changing rapidly, and our understanding of the disease itself is evolving. While much has been written about the respiratory symptoms of Covid-19, little has been written about its potential impact on the eye.
As of 5/2020, a search on covid-19 and ocular returned about 22 publications, almost all from 2020. A wider search on "eye" subject word and covid-19 returned about 100 papers. Siedleck et al(2020) reviewed the literature as of April 2020, and reviewed 21 peer reviewed articles related to Covid-19 and the eyes. So there is already a substantial literature as of mid 2020.
As Covid-19 enters through the nose, and the nose and eyes are adjacent and connected through the tear ducts, one would think that a person who breathes in Covid-19, might also be able to get Covid-19 through droplets that enter through the eye.
There have been several reports of conjunctivitis (inflamation of the lining of the eye) being associated with Covid-19. One of the first doctors in China who noticed the epidemic was an ophthalmologist (Li Wenliang). He was believed to have contracted the virus from an asymptomatic glaucoma patient in his cliic.
Wu et al (2020) described ocular findings in China in individuals with Covid-19. Based on a study of 38 patients with Covid-19 in the nose, 5.2% also had positive Covid-19 in their tears. A total of 12 of 38 patients (31.6%; 95% CI, 17.5-48.7) had ocular manifestations consistent with conjunctivitis, including conjunctival hyperemia, chemosis, epiphora, or increased secretions. They stated that "one-third of patients with COVID-19 had ocular abnormalities, which frequently occurred in patients with more severe COVID-19. Although there is a low prevalence of SARS-CoV-2 in tears, it is possible to transmit via the eyes. ".
Robbins (1991) reported that the mouse hepatitis virus can cause long standing retinal disorders (in mice).
Xie et al (2020) also reported a small number (2/33) of patients with Covid-19 and virus in their tears. There are also numerous case reports of conjunctivitis in the context of Covid-19.
Hong et al (2020), in a study of 56 patients with Covid-19, found that there was a rather high prevalence of ocular symptoms (about 27%). They stated "Our data provided the anecdotal evidences of transmission of SARS-CoV-2 via ocular surface." Note that these patients did not have the virus found in tears.
Zhoua et al (2020), in an unreviewed and unpublished work posted to a scientific pre-publication site, reported that the eye expresses ACE2, which is an entry point for Covid-19. This suggests that in addition to the idea proposed above (virus gets into eye and then into nose through tears), it might also infect the eye itself, which then could express virus and spread to other parts of the body.
The opposite opinion was expressed by Lange et al (2020). They stated that "this study finds no evidence for a significant expression of ACE2 and its auxiliary mediators for cell entry in conjunctival samples, making conjunctival infection with SARS-CoV-2 via these mediators unlikely. "
Covid-19 might also faciliate viral conjunctivitis by reducing the immune system efficiency, and allowing other viruses or bacteria to infect the eye.
One possible route for coronavirus entry into the body is through the eyes, and a uncommon manifestation of coronavirus infection is conjunctivitis. There are many responses to this information.
- According to Sadhu et al (2020), ophthalmic healthcare professionals are at higher risk of contracting the virus.
- According to Pult et al (2020), most optometrists do not plan to wear eye protection themselves, but they are practicing the same standards as most other practitioners (i.e. masks, sanitising, hand washing, gloves)
- According to Scalini and Battagliola (2020), "eye protection in the form of goggles or a face shield should be considered essential for all healthcare providers, even when taking care of patients who are not showing typical symptoms of COVID-19"
- According to Zang et al (2020), "To lower the SARS-CoV-2 nosocomial infection, all health care professionals should wear protective goggles." They also stated that "Our findings suspect the incidence of SARS-CoV-2 infection through the ocular surface is extremely low, while the nosocomial infection of SARS-CoV-2 through the eyes after occupational exposure is a potential route."
- According to Kowalski et al (2020), "For any care or intervention in the upper aerodigestive tract region, irrespective of the setting and a confirmed diagnosis (eg, rhinoscopy or flexible laryngoscopy in the outpatient setting and tracheostomy or rigid endoscopy under anesthesia), it is strongly recommended that all health care personnel wear personal protective equipment such as N95, gown, cap, eye protection, and gloves. "