The RP Centre for Ophthalmic Sciences at AIIMS is conducting a study to ascertain the presence of the coronavirus in various parts of the eye of those who have died due to the infection, the centre's chief Dr JS Titiyal said on Tuesday.
Addressing a press conference on the 36th Eye Donation Fortnight celebration by the National Eye Bank (NEB), he said that five eye balls have been collected for carrying out the study.
"The research study will help ascertain the presence of the coronavirus in the cornea, optic nerve and retina of COVID-19 infected deceased," Dr Titiyal said.
"These eye balls will be subjected to various molecular tests to detect presence of the Covid virus in these tissues and also look for genetic evidence," he said.
Dr Namrata Sharma of the RP Centre said that there is no proven evidence so far which establishes any direct link between COVID-19 leading to blindness.
Because of COVID-19, cases of conjunctivitis have been reported but that does not lead to vision loss. COVID-19 leads to mucormycosis and there have been cases where it has impacted vision and lead to blindness, she said.
"There have been isolated cases of retinal and Venus blocks which may lead to sudden diminishing of vision due to thromboembolism . But there has been no proven cause and effect relationship between them so far," Dr Sharma said.
Tissue retrieval is performed only from presumed COVID-19 negative donors, according to established eye banking guidelines, she said.
"To ensure maximum safety we perform a post-mortem nasopharyngeal swab RT-PCR testing for all our potential donors. Of the tissues retrieved by us between July 2020 and July 2021, we found that 5.5 per cent of the presumed COVID-19 negative donors tested RT-PCR positive for SARS-CoV2," Dr Sharma said.
The tissues from these donors were not used for corneal transplantation and were subjected to further microbiological analysis, she said.
Eye banking services have been one of the worst hit by the COVID-19 pandemic, Dr Titiyal said.
Corneal tissue retrieval activities by the NEB which remained suspended from April 2020 to June 2020 during the nationwide lockdown were restarted through the hospital cornea retrieval program (HCRP) from July 2020 onwards.
From April 2020 to March 2021, the NEB collected 394 corneal tissues, and 311 keratoplasties were performed amounting to a utilisation rate of 78.9 per cent, Dr Titiyal said.
The national tissue collection and utilisation during this period was 18,359 and 12,998 respectively, amounting to a utilisation rate of 70.7 per cent, he said.
As compared to the corresponding period April 2019-March 2020, the NEB witnessed a 79.9 per cent decrease in tissue collection and 78.2 per cent decrease in tissue utilisation, demonstrating the severe impact of the COVID-19 pandemic on its activities.
The corneal tissue collection recommenced in July 2020 and peaked by January 2021. The collection figures steadily declined thereafter until May 2021, corresponding to the second wave of the pandemic, after which it has again shown an ascending trend.
Reinitiating corneal retrieval during the pandemic required the NEB to train its staff, including counsellors and paramedic personnel, in the use of personal protective equipment and the additional step of retrieval of nasopharyngeal swab for RT-PCR of donor.
Corneal tissue retrievals are performed in adherence to the prescribed COVID-19 preventive guidelines and none of our staff have been infected during tissue retrieval or processing, Dr Titiyal said.
For the last several years, the R P Centre is helping in the functioning of other eye banks by providing them with corneal preservation storage media (MK media), which is indigenously manufactured at the centre's department of ocular pharmacology and funded the government.
As many as 3,274 vials of MK media were distributed outside RP Centre between October 2019 and March 2021.
The NEB is routinely organising programmes in schools, colleges and residential areas to promote awareness regarding eye donation. This year, a cyclothon was organised on September 5 from AIIMS to India Gate as a part of this effort.