Ophthalmic use of amniotic membrane tissue in Australia: Introduction and initial use of a service

Abstract

Amniotic membrane (AM) has been used across ophthalmology for almost 80 years. AM has been shown to stimulate wound repair while suppressing inflammation, angiogenesis and scarring offering potential opportunities for the successful treatment of an increasing number of ophthalmic indications. Essential for use in ocular surgery, the tissue is non-reactive and largely transparent. Recently, the New South Wales Organ & Tissue Donation Service (NSW OTDS) established an AM retrieval and processing pathway to support local surgical demand. The process of AM retrieval follows standard living donor protocols inclusive of strict exclusion criteria. Following consent, AM is accessed through planned caesarean birth and full-term pregnancy. After procurement, tissue is placed within a sterile medium and kept between 2-8 degrees for transport. At the preparation stage, AM is separated from the chorion, decontaminated and incubated with antibiotic and antimycotic solutions before application to a carrier surface (nitrocellulose paper) which is then cut into standard dimensions (5 × 5 cm, 5 × 10 cm, 10 × 10 cm). AM is then cryopreserved up to a period of 12 months from day of retrieval. Microbiology is performed both as a batch and as individual grafts to exclude organism contamination (prior to bioburden reduction, post-production swab of individual graft and culture of both wash solution and remnant). All donors are followed up after routine new-born checks via a phone interview to exclude post-donation concerns. Beginning in 18 October 2018 separate AM donations have been accessed principally through the Mater Hospital (North Sydney, NSW, Australia). The mean age of mothers was 36.2 ± 4.1 years (range 28 to 40 years). An average of 26.3 tissue sections were processed from primary donor tissue (median 25, range 12 to 38). 16 AM sections of nine patients were found to be positive for microbiology and were either removed from consideration or utilized for research purposes only. Microbiology findings were consistent with the patient-hospital environment and or contamination (S. epidermis, S. cohnii, S. Warneri, Cutibacterium acnes, Paenibacillus urinalis, Paenibacillus sp). Following the introduction of the service, NSW OTDS has received 119 AM tissue requests with the absolute majority for ophthalmic indications (96.6%). Requests have been received and completed from 58 ophthalmic surgeons across all states and territories except Northern Territory suggesting a basic national demand for AM. Fifty-nine percent of recipients were male with a mean age of 64.0 ± 17.3 years (range 6 to 93) corresponding with population findings from the existing ophthalmic literature. Seven patients required multiple tissue applications for surface reconstruction or tectonic repair (neoplasia, corneal ulcer at risk of perforation, infectious scleritis and alkali burn). Tissue requests largely reflect the potential benefits of AM transplantation which include faster wound healing, minimization of pain and inflammation and the prevention of surgical adhesion. The indications for AM request are presented in Figure 1. Almost a third (32.8%) of requests were to assist surface reconstruction following the removal of ocular neoplasia. Initial surgeon feedback suggested inappropriate sizing of provided AM tissue in 10 samples however surgery proceeded without incident in each case. Increasing familiarity with AM tissue is likely to further minimize this as an ongoing issue. In three cases, AM tissue was prematurely dislodged requiring readhesion. No other complications were reported either at surgery or through the short-term recovery period. A review of the literature suggests that the use of AM tissue in Australia varies from other countries (Table 1). The leading indication in Mexico and Italian populations is pterygium and corneal ulcer repair, respectively. 3,4 The incidence of ocular surface neoplasia has been shown to be significantly greater in the southern hemisphere which may have contributed to the increased representation in the local population by comparison. Our sample remains small however and the increased awareness and use of the AM tissue utility is likely to see the list evolve further. In less than 12 months, requests for AM tissue have continued to increase. With minimal surgical complications