The nucleocapsid protein antigens of SARS-CoV-2 have been identified within the inner ocular tissues of a patient previously infected with COVID-19, according to newly issued research published in JAMA Ophthalmology. This is the first direct evidence showing the virus within those structures, implying that it can infect ocular tissues separate from the respiratory system.
Previous reporting did show that the virus can be detected in the conjunctival sac of COVID-19 patients using reverse transcriptase–polymerase chain reaction (RT-PCR). However, those reports only found low conjunctival sac infection rates. This study was unique in that it was able to provide an ocular specimen from a patient who underwent surgery for an acute glaucoma attack, after recently recovering from COVID-19.
The patient, a 64-year-old female, underwent bilateral phacoemulsification surgery 7 weeks after the initial onset of COVID-19 symptoms. Tissue samples of her anterior lens capsular were collected during this surgery. Because of the uncontrollable intraocular pressure (IOP) in her right eye after phacoemulsification surgery, she underwent trabeculectomy surgery 4 additional weeks later. During that procedure, additional samples of her conjunctiva, trabecular, and iris were collected. Control specimens were collected on the same 2dates from other patients who had tested negative for SARS-CoV-2 infection.
Nucleocapsid protein antigens were detected on the cells of the conjunctiva, iris, and trabecular meshwork specimens of the test subject. These antigens were absent on the specimens from the control patient. In addition, angiotensin-converting enzyme 2 (ACE2) receptor proteins were detected in the conjunctiva cells of both patients. Researchers speculated that “SARS-CoV-2 could enter the inner eye tissue via the ACE2 receptor on the surface of the conjunctiva,” but explained that “this hypothesis can only be confirmed through animal experiments — for example, ones that detect the virus in the intraocular tissue after conjunctiva inoculation.”
The patient first developed COVID-19 symptoms in late January. During the course of her SARS-CoV-2 infection, she was hospitalized and given antiviral and antibacterial treatments, as well as supplemental oxygen, as empirical therapy. The report noted her symptoms began to resolve on day 18. During this period, she had no ocular symptoms. Less than 2 weeks after her stay, she began to experience persistent pain and acuity loss. Soon, her acuity was light perception bilaterally. Her intraocular pressures were elevated to 50 mm Hg in both eyes. She also displayed bilateral conjunctival hyperemia, corneal edema, dilated (5 mm diameter) and fixed pupils, flat anterior chambers, and lens opacity (grade 3). She was diagnosed with acute angle-closure glaucoma and cataract.
The investigators concluded that any follow-up research should aim to determine whether the viral nucleocapsid protein antigens that remain in these inner ocular tissue following a SARS-Cov-2 infection can cause damage to the eye’s structure or function, represent the presence of active viral residues in organs (not only the eyes), or are still infectious.
Yan Y, Diao B, Liu Y, et al. 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