COVID-19 patients' eyes and tears can be infected with SARS-CoV-2

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is present in respiratory droplets. Transmission of SARS-CoV-2 through droplets can infect people, thus causing coronavirus disease 2019 (COVID-19). A new study published in the journal Vision investigates the presence of SARS-CoV-2 in tears and eye secretions and describes the ocular symptoms in patients with COVID-19.

Study: SARS-CoV-2 in Conjunctiva and Tears and Ocular Symptoms of Patients with COVID-19. Image Credit: /

COVID-19 symptoms

Patients with COVID-19 often present with fever, cough, shortness of breath, muscle weakness and pain, as well as various gastrointestinal symptoms. Patients with severe COVID-19 may also develop bilateral pneumonia and hypoxemia. When severe COVID-19 leads to cytokine storms, multiple organs can get affected.

SARS-CoV-2 has been detected in tears and conjunctival secretions, mostly in patients with severe COVID-19. These patients also demonstrate ocular manifestations of the disease.

A cross-sectional study

In the current cross-sectional cohort study, scientists enrolled 56 hospitalized patients. This was a single-site study conducted at the University Hospital of Santiago de Compostela in Spain.

Patients were eligible to participate in the current study if they had reverse-transcriptase polymerase chain reaction (RT-PCR)-confirmed SARS-CoV-2 infection from a nasopharyngeal swab and were within the first 20 days from the onset of symptoms. Patients from the intensive care unit or with a poor general condition were excluded from this study.

Conjunctival secretions and tears were collected using flocked swabs and Schirmer strips for performing RT-PCR. The scientists assessed the ocular surface manifestations through an Ocular Surface Disease Index (OSDI) questionnaire.

Prevalence of SARS-CoV-2 in conjunctival samples

Of the 56 patients enrolled in this study, 32 were male and 24 were female. The mean age of the patients was 69 years, ranging from 27 to 89 years. The disease severity was mild in five patients, moderate in 30 patients, and severe in 21 patients.

Patients had been admitted to the hospital for an average of 2.4 days before ocular testing. The mean time from the onset of general symptoms until the collection of ocular samples was 7.1 days.

The following percentage of patients had systemic comorbidity: hypertension, 48.2%; diabetes, 28.6%; cancer, 23.2%; heart disease, 21.4%; obesity, 17.9%; and chronic lung disease, 16%. Nineteen patients (33.9%) had reported previous ocular conditions, including cataract surgery (16.1%), glaucoma (5.4%), retinal vein occlusion (3.6%), strabismus (3.6%), uveitis (1.8%), refractive surgery (1.8%), and diabetic retinopathy (1.8%).

Four (7.1%) of the 56 conjunctival swabs samples and four (3.6%) of 112 Schirmer strips tested positive for SARS-CoV-2. In the four patients with positive conjunctival swab samples, Schirmer strip samples were negative in both eyes in one patient, positive only in the left eye in two patients, and positive in both eyes in one patient. None of the patients had both a negative conjunctival swab and a positive Schirmer strip sample.

There was no association observed between the RT-PCR test from ocular samples and ocular symptoms. Twenty-nine percent of patients with a negative RT-PCR and 25% of patients with positive ocular RT-PCR had ocular symptoms. Three of the patients had a moderate illness and one presented a severe course of the disease. Overall, 17 (30%) patients presented ocular symptoms.

The scientists concluded that the viral load was low on the ocular surface because the cycle threshold (Ct) values were high in ocular samples. The patient with positive conjunctival and tear samples in both eyes had a higher viral load in the eyes when compared to the other patients. Only one patient had a high viral load in the eyes than in the nasopharynx. Interestingly, this patient demonstrated more severe systemic disease.

Limitations of the study

Some of the limitations of the current study include a small sample size, as well as the fact that the nasopharyngeal and ocular samples were taken during different stages of the disease. This may affect the homogeneity of the results.

Additionally, the scientists could not perform slit lamp examinations or biomicroscopy to examine the eyes of the patients for any abnormalities or problems.


The current study shows that SARS-CoV-2 can be detected in the conjunctiva and tears of patients with COVID-19. The 7.1% prevalence of SARS-CoV-2 in conjunctival samples found in this study is comparable to previously reported rates.

The results from this study and previous studies indicate that the ocular surface can act as an entry point and reservoir for the transmission of SAR-CoV-2. Contact with the ocular surface may transmit the virus; therefore, commercial ocular antiseptics may help with avoiding transmission and preventing ocular symptoms during COVID-19 infection.

Health care professionals, particularly eye care providers, should be aware of ocular transmission and follow strict disinfection protocols.

Journal reference:
  • Rodríguez-Ares, T., Lamas-Francis, D., Treviño, M., et al. (2021) SARS-CoV-2 in Conjunctiva and Tears and Ocular Symptoms of Patients with COVID-19. Vision 5(4):51. doi:10.3390/vision5040051
Dr. Shital Sarah Ahaley

Written by

Dr. Shital Sarah Ahaley

Dr. Shital Sarah Ahaley is a medical writer. She completed her Bachelor's and Master's degree in Microbiology at the University of Pune. She then completed her Ph.D. at the Indian Institute of Science, Bengaluru where she studied muscle development and muscle diseases. After her Ph.D., she worked at the Indian Institute of Science, Education, and Research, Pune as a post-doctoral fellow. She then acquired and executed an independent grant from the DBT-Wellcome Trust India Alliance as an Early Career Fellow. Her work focused on RNA binding proteins and Hedgehog signaling.


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