It is nice to have yet another issue of IJO, the official publication of AIOS out
in print with a bevy of interesting articles packed with new information. This issue
of the journal carries a paper investigating serology results in cornea donors, comparing
the reports from donors who died in hospital whose corneas were retrieved under the
Hospital Cornea Recovery Program (HCRP) with those recovered from voluntary home deaths.
The article has raised the specter of donor transmission of dreaded diseases.
Irrespective of the outcomes of comparison of the two pools of donors, the paper unquestionably
reaffirms what we know already – there is a silent presence of sinister diseases which
patients, relatives, or caregivers are not aware of and the condition is unveiled
only by routine serological screening of asymptomatic individuals. In short, it is
a sober reminder that serological testing of eye donors is mandatory and we hope that
there are no longer any eye banks in the country not following National Programme
for Control of Blindness guidelines. The Eye Bank Association of India has played
a key role in assisting in the process of dissemination of information to all stakeholders,
further substantiated and reinforced by the requirement as per the Transplantation
of Human Organs and Tissues Act checklist for legal registration.
Another aspect the paper uncovers is that in this particular patient population, there
was a difference in seroprevalence of blood- and tissue-borne infections between HCRP
and voluntary home donors with a higher likelihood among those who were admitted and
died in hospital. Consequently, it highlights that the well-placed enthusiastic emphasis
on hospital recovery motivated by better efficiency and utilization rates must be
tempered by the ground reality that these cases may harbor higher than the expected
transmission risks. Hence, more vigilance is required in screening the blood samples,
using reliable testing methods, and extra care must be exercised in interpreting the
findings before clearing the tissue as safe for transplantation.
In the study reported in this issue, enzyme immunoassay (EIA)-based rapid diagnostic
test (RDT) kits have been used for the HIV, hepatitis B virus (HBV), and hepatitis
C virus (HCV) serologies. The manuscript states that test results (of the specified
rapid EIA-based government-approved kits) were double checked by ELISA, but the names
and manufacturers of the ELISA kits used for verification are not mentioned. For HIV
and HCV, RDTs are considered to have acceptable sensitivity and specificity. These
tests are included in national guidelines for HIV testing (NACO, 2015);[1] and for
HCV antibody testing, some RDTs are also WHO prequalified.[2] However, many RDTs are
unable to detect low levels of HBV surface antigen, particularly in asymptomatic individuals.[2]
In view of time constraints, good quality rapid tests would be a particularly useful
option for screening cadaveric corneal donors.
An issue which needs to be considered while screening cadaveric (postmortem) samples
is that a very small percentage of false-positive and even more rarely, false-negative
results, have been reported on comparison with premortem samples.[3] It is probably
better to err on the side of caution, and corneas from all serologically positive
donors, including the false-positive ones, should not be transplanted, treating this
as acceptable wastage in the interest of preventing transmission of infection. This
is of relevance, because in the rare case of an adverse event of the recipient ever
acquiring one of the blood- and tissue-borne diseases after corneal transplantation,
the decision to use the tissue despite a positive result can be questionable.
In an attempt to eliminate false-negative results, in many developed countries, screening
by nucleic acid tests (NAT) is also recommended. However, given the known prevalence
of HIV, and the low-to-intermediate endemicity of HBV and HCV in India[2
4] the probability of donors being in the window period (negative serology with a
positive NAT) at the time of screening is quite negligible, and these expensive tests
are unlikely to provide any real benefit in terms of additional “yield” of infected
donors.
Of course, the local and regional variations will impact the practical implications,
but a strong emphasis of reliance on serological tests to support the mandatory screening
for medical history, social and behavioral risk factors, and physical examination
of the donor to ensure full safety of recipients demands a relook at the quality of
testing techniques and the reliability of their interpretation. A shift to processing
of blood samples by professional facilities with reporting by experts, a transition
many eye banks in India have already made, rather than simply depending on underqualified
eye bank technicians, may have to be considered.
Finally, some food for thought, are we to believe that safety standards[5
6
7
8
9
10] should be equivalent globally? Ethical concerns would recommend so, but economic
and technical constraints may play an unseemly role in searching for a safe-enough
acceptable alternative. The point of the matter is, what some perceive as increasing
costs and complexities in eye banking, others may view as a valid price to pay to
ensure safety and eliminate risks. As the country has progressed from gloveless, drapeless
eye surgeries to near state-of-the-art protective measures, so must the eye banking
and corneal transplantation community rise to the occasion by driving for change in
mindsets that quality does come for a price and we must find ways to make it affordably
available.
About the author
Prof. Radhika Tandon currently heads the clinical unit providing Cornea and External
Disease, Cataract and Refractive Surgery, Ocular Oncology and Low Vision Services
at the Dr. Rajendra Prasad Centre for Ophthalmic Sciences, AIIMS, New Delhi. She is
also the Co-chairperson of the National Eye Bank, Chairperson of Low Vision Services
and Chairperson of the Medical Board Ophthalmology. Her extramural positions include
Chairperson Visual Disabilities Sub-committee of Ministry of Social Justice and Empowerment,
Ophthalmology Expert for Medical Council of India, Technical Expert for Directorate
for Health Research, Member of Advisory Board for National Program for Control of
Blindness, Task Force member for Department of Biotechnology and Indian Council for
Medical Research, Member of Apex Technical Committee for National Organ and Tissue
Transplant Organization, and elected President of Eye Bank Association of India. Endowed
with a sharp, analytical mind and high intellectual capabilities, coupled with a brilliant
academic record, Professor Tandon is a graduate and post graduate from AIIMS, and
is devoted to an academic career balancing patient care, teaching and research with
numerous publications to her credit. She is well known as co-editor of the renowned
textbook Parsons’ Diseases of the Eye. Her work on standardization of eye banking
in India has resulted in a paradigm change.