Researchers found the nucleocapsid protein (NP) antigen of SARS-CoV-2, the virus which causes coronavirus disease 2019 (COVID-19), existed intracellularly in the ocular tissues of a patient who previously had COVID-19.
Researchers found the nucleocapsid protein (NP) antigen of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID-19), existed intracellularly in the ocular tissues of a patient who previously had COVID-19 and suffered an acute glaucoma attack during her rehabilitation. The case study was published in JAMA Ophthalmology.
“Based on these results, the eye is also one of the target organs for the viral infection in addition to the lungs,” authors wrote.
It was previously unknown whether SARS-CoV-2 can also infect tissues besides the respiratory system, while no direct evidence had been published showing SARS-CoV-2 existed in inner ocular tissues.
In the current case, as the patient needed to undergo ophthalmic surgery, researchers performed surgical ocular specimen removal and compared samples to that of a control patient.
The 64-year-old female patient presented with a dry cough for 5 days and diarrhea for 9 days before she went to a hospital in Wuhan, China, on January 31, 2020. The patient tested positive for COVID-19 and was “admitted to the hospital to receive antiviral and antibacterial treatment, as well as supplemental oxygen, as empirical therapy.”
No serious respiratory or ocular symptoms were observed during the woman’s 18-day stay. On February 18 and 20, the woman tested negative for COVID-19 via 2 throat swab reverse transcription polymerase chain reaction (RT-PCR) tests.
However, on February 28, the patient began experiencing persistent left eye pain and visual acuity loss, and after 3 days the same symptoms presented in her right eye. On March 8, the patient was admitted to an ophthalmology clinic and was diagnosed with acute angle-closure glaucoma and cataract.
“Because her intraocular pressure could not be lowered by medication, phacoemulsification surgery was performed on her left and right eyes on March 14 and 15, respectively, and tissue samples of the anterior lens capsular were collected during this surgery,” authors wrote. They continued, “because of the uncontrollable intraocular pressure in her right eye after phacoemulsification surgery, she underwent trabeculectomy surgery on April 10. Samples of the conjunctiva, trabecular, and iris were collected during this surgery.”
On April 10, the researchers also collected control specimens from a 61-year-old male with glaucoma who underwent a trabeculectomy surgery. The control patient had not been infected with COVID-19, determined via 2 negative RT-PCR throat swabs, negative chest computed tomography, and blood test results.
Researchers noted the method used to detect the SARS-CoV-2 NP antigen was similar to the method used in a previous investigation of lung and kidney autopsy specimens.
How the virus enters the eye is still unclear. However, authors hypothesized SARS-CoV-2 may enter the inner eye tissue via the angiotensin-converting enzyme 2 receptor on the surface of the conjunctiva or the virus may spread systemically to end organs as a result of the primary respiratory infection.
In addition, the patient in the case study was not in the acute period of infection while the transmission route was short of definite evidence, marking 2 limitations to the study.
“The viral antigen detected in the eye of the patient 2 months after infection should prompt future investigations,” researchers concluded.
“These investigations should aim to determine whether the viral NP antigens that remain in the eye over time cause damage to the ocular structure or function, represent the presence of active viral residues in organs (not only the eyes), and are still infectious.”
Yan Y, Diao B, Liu Y, Zhang W, Wang G, Chen X. Severe acute respiratory syndrome coronavirus 2 nucleocapsid protein in the ocular tissues of a patient previously infected with coronavirus disease 2019. JAMA Ophthalmol. Published online October 8, 2020. doi:10.1001/jamaophthalmol.2020.3962