Amniotic membrane transplantation

Amniotic membrane transplantation consists of applying a piece of amniotic membrane to the surface of the eye. This piece is usually attached to the tissue by means of fine sutures. There are two different methods of application, depending on the type of injury: dressing or graft.

If there is only one defect in the epithelium (the outermost layer of the cornea or conjunctiva), but the stroma (the layer underneath) is healthy, the amniotic membrane is used as a dressing that covers the entire surface. The growth factors that the membrane contains cause the epithelial cells to begin to grow underneath it. After a few days, the membrane can be easily removed in the doctor’s surgery, leaving no traces.

The amniotic membrane triggers a rapid wound healing process that can last between 2 and 15 days, depending on the eye condition that is being treated.

In cases of deeper injury involving loss of the stroma, the membrane is grafted, filling the gap left by the missing stroma. With this method, the cells do not grow underneath, as is the case when the dressing is placed on the epithelium, but do so on top, until the membrane, which gradually becomes absorbed, is replaced. Grafting involves a slower healing process with the membrane taking several months to be absorbed. During this time, the amniotic membrane can make the eye opaque, which temporarily limits vision.

Amniotic membrane transplantation is particularly indicated for acute-phase burns caused by caustic substances, such as bleach and lime, in which tissue is devitalised, inflamed or is encountering regeneration problems.

It is also often used after extensive conjunctival resection (generally the removal of tumours or scarring), as well as for ulcers and corneal and conjunctival epithelial defects.

It can also be used to increase the chances of success in some corneal surgery, such as corneal transplantation, and in cases where postoperative problems of tissue regeneration or scarring are anticipated.