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Amniotic membrane transplantation in ophthalmology (fresh v preserved tissue)
  1. Cornea Service, Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute
  2. Of Medical Sciences
  3. New Delhi, India
  1. B P Koirala Institute of Health Sciences, Dharan, Nepal
  1. Department of Ophthalmology
  2. B Floor, South Block
  3. University Hospital
  4. Queen's Medical Centre
  5. Nottingham NG7 2UH

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    Editor,—Research on amniotic membrane transplantation in conjunctival and corneal disorders has been gaining popularity for the past 5 years.1 2 Though the concept is as old as six decades it has remained dormant over the years owing to unmentioned/unidentified factors.3 In 1996, we performed our first amniotic membrane transplant following surgery for recurrent pterygium with successful results. The procedure was similar to that of Tseng et al in 1998.1 We followed the method of preparation of the graft as mentioned by Sorsbyet al in 1947.3 We are strictly following the conventional method of tissue harvesting and preservation for clinical use.4 5

    However, we conducted a small study in six monkeys by using fresh amniotic membrane in six eyes, and in the six contralateral eyes preserved (−80°C) amniotic membrane (control) was used. Tissue harvesting was from elective caesarean section delivery. Processing of the tissue was by the conventional procedure followed worldwide in both the groups. An intentional 7 × 7 × 0.2 mm anterior keratectomy was made in all eyes. In one eye freshly obtained amniotic membrane was transplanted, while in the fellow eye −80°C preserved tissue was transplanted after opening the first eye. The eyelids were closed for 2 weeks. All the animals received intramuscular antibiotics for 1 week and intramuscular corticosteroids 1 g/kg/body weight for 2 weeks. The eyes were opened after 2 weeks. All the defects were healed and the corneas looked normal. From our small study it was evident that there was no difference in healing irrespective of method of preservation. However, to date no report has appeared on utilisation of freshly prepared amniotic membrane tissue transplantation. Though we routinely transplant amniotic membrane using the conventional method of preserved tissue, I would like to know the experience of other corneal surgeons who perform the procedure frequently, about the possibility of using fresh tissue clinically. I strongly feel that the procedure of amniotic membrane transplantation in a very safe, simple, and satisfactory method for treating conjunctival and corneal disorders; it can be practised by all corneal surgeons, even those who do not have access to −80°C facility.



    Editor,—Dr Panda's letter essentially asks the question whether fresh amniotic membrane would be as good as preserved (−80°C) amniotic membrane. An amniotic membrane may act as a biological bandage, as a basement membrane (substrate) transplant, or via several favourable growth factors and cytokines that promote healing and epithelial cell migration. If the last of these mechanisms of action of the membrane is important, then theoretically, fresh membrane should work better than preserved membrane. There is, however, no hard evidence to support this view yet. The experiment on monkeys, quoted in the letter by Dr Panda, suffers from the drawback, as do several published papers on use of amniotic membrane, of having no controls. It is very possible that the experimental epithelial defects created in healthy corneas of monkeys would have healed just as well without the use of either fresh or preserved membrane. Closing the eyelids for 2 weeks would itself have a very favourable influence on corneal epithelial wound healing.

    The issue, whether fresh is as good as (or better than) preserved, is somewhat sidelined by the concern over the risk of HIV infection. One of the main reasons for using preserved tissue is to enable one to perform a test for HIV infection, on the donor mother, at the time of harvesting the membrane and 6 months later, to cover the window period. As one harvested membrane can be used for several recipients, there is a risk of widespread infection in case of contamination. For this and other issues related to amniotic membrane transplantation, we would like to draw attention to the review by Dua and Azuara-Blanco.