Abstract
Purpose :
Corneas screened positive for viral serology are unable to be used for clinical transplantation. By identifying factors which may lead to false positive results, we may be able to avoid those factors and maximise usage of donated corneal tissues.
Methods :
Donor corneas stored in organ culture medium at the New South Wales Tissue Banks between March 7, 2005 and March 20, 2018 were reviewed retrospectively.
Donor suitability was determined with a thorough medical history review prior to retrieval. Post mortem blood samples were collected at the time of eye retrieval within 24 hours from circulatory standstill. Corneas were screened with enzyme-linked immunosorbent assay for hepatitis B surface antigen (HBsAg), hepatitis C antibodies (HCAb) and human immunodeficiency virus 1 and 2 antibodies (HIV1+2Ab). Positive screen results were further confirmed with polymerase chain reaction or nucleic acid testing, and categorised as either true positive (TP), false positive (FP) or not tested. c2 test was used to assess the association between pre or post mortem sampling, haemolysis level and interval from circulatory standstill to enucleation (ICSE).
Results :
A total of 5124 corneas were collected. 178 (3.5%) corneas were unable to be used for transplantation due to positive screening for HBsAg, HCAb and HIV1+2. Of the 144 (89%) corneas that underwent confirmatory tests, 61% were post-mortem samples. There were 63 corneas positive for HBsAg, with 11 TP and 32 FP (74%) after confirmatory testing. In the HCAb group 67 corneas were positive, with 33 TP and 24 FP (42%). Of 48 corneas positive for HIVAb1+2, 5 were TP and 39 FP (92%).
Pre or post mortem blood sampling was found to be statistically significant in predicting false positives for Hep B (p = 0.004) but not for Hep C (p = 0.573) or HIV (p = 0.387). In addition, haemolysis level was significantly related to false positives for Hep B (p = 0.027) but ICSE did not show a relationship (p = 0.706).
Conclusions :
The high false positive results in HBsAg (74%) and HIV1+2 (92%) groups should be addressed. The pre or post sample types and haemolysis level impacts on false positive serology while ICSE does not contribute to false positive results. These finding may suggest that the 24 hour ICSE is meeting sample test criteria and tissue banks should consider using pre-mortem blood sample when it is available.
This is a 2020 ARVO Annual Meeting abstract.