In another rare case, the SARS-CoV-2, the virus behind the deadly Covid-19 pandemic, was found in the tears of patients with no eye diseases, according to a recent study by researchers from the All India Institute of Medical Sciences (AIIMS).
In the study, published in the journal Cureus, the team included 40 patients, with 26 (65 per cent) classified as having moderate Covid, six (15 per cent) classified as having severe Covid, and the remaining having mild Covid.
Out of the 40 patients, five (12 per cent) tested positive for SARS-CoV-2 in the tear sample using RT-PCR.
Among these five positive cases, only 20 per cent displayed ocular manifestations, while the remaining 80 per cent did not exhibit any signs of ocular symptoms.
In addition, seven patients (17 per cent) showed ocular symptoms such as conjunctival hyperemia, epiphora, watering, and itching, of which only 14 per cent tested positive for SARS-CoV-2 in RT-PCR tear samples.
The remaining six patients tested negative for SARS-CoV-2 in tear samples.
"Notably, we detected a positive Covid-19 tear sample in patients both with and without ocular symptoms," said Kanishk Singh, and team from the department of Ophthalmology at AIIMS Nagpur, in the paper.
The researchers said that so far, limited reports have focused on ocular involvement in patients with Covid-19. However, the study demonstrates the detection of SARS-CoV-2 in conjunctival swabs from confirmed Covid patients, albeit with a lower positivity rate.
"Despite the low prevalence of the virus found in tears, there is a potential risk of transmission through ocular routes. Therefore, it is important to consider the possibility of ocular transmission even in the absence of ocular manifestations. Medical personnel should take careful precautions during ocular examinations of patients diagnosed with Covid to minimise the risk of transmission," the researchers said.
Notably, the viral load in conjunctival samples is generally lower when compared to nasopharyngeal secretions.
"Despite this disparity, concerns persist regarding the potential transmission of the disease through tear samples, even when obvious ocular signs and symptoms are absent. Thus, it is emphasised that relying solely on tear samples for diagnosing Covid-19 should be avoided, and they cannot be considered a substitute for other established diagnostic methods," the team said.
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