#amnioticmembrane

As a response to this, there are several treatments that range from the use of topic anti-inflammatory drugs or antibiotics, to corneal transplantation –more specifically, amniotic membrane transplantation –, which is the subject of this brief discussion.

The amnion is the sac surrounding and protecting the developing embryo.  Ever since 1910, when a surgeon first reported the use of fetal membranes as surgical material in skin, the use of amniotic membrane in surgery has been revised. In the following decades, numerous researchers reported the advantageous role of the amniotic membrane for the treatment of a variety of ocular surface disorders, without a clear or approved medical application, resulting in the abandonment of the technique.  Nevertheless, recently, it has been making its way back into ophthalmological practice. The relevance of the subject is the scope that the application of amniotic membrane transplantation (AMT) in the management of ocular surface disorders offers.

There are a number of applications for AMT given its transparency, low cost, availability as a surgical spare tissue, non-immunogenicity in a cryopreserved state, anti-inflammatory properties, and the natural antimicrobials present in its epithelial layer. Also, amniotic membrane contains growth factors and expresses anti-inflammatory cytokines that accelerate the healing of the tissue. Among the indications in ophthalmology are the persistent epithelial defects unresponsive to medical treatment, and its use as an alternative to conjunctival flaps, botulinum toxin injection, or tarsorrhaphy; with a very high success ratio. Regarding tissue engineering methods, AMT has a potential use in combination with limbal transplantation in patients with diffuse limbal stem cell deficiency and in diseases such as Stevens–Johnson syndrome or chemical and thermal burns.

Generally, for the preparation of the membrane, after harvesting human placenta from a healthy woman during a cesarean section, the amnion is isolated from the chorion, washed in sterile physiological solution, put on nitrocellulose membrane fragments, and cryopreserved. The amnion as a scaffold with an intact epithelial layer has been proposed as an optimal choice for clinical usage since it has been proven to accelerate epithelialization of eye defects by promoting the migration of epithelial cells, their adherence to the basement membrane, and differentiation; along with the prevention of apoptosis. It also induces cell proliferation by secreting molecules with immunoregulatory and angiogenic properties.

However, as every technique, amniotic membrane transplantation in the human eye also has its limitations. One of them is a shown failure in the case of its use when impending or recent corneal perforation is present. Another example would be the higher rate of recurrence – almost five times higher – of pterygium when compared to an autologous conjunctival graft during the removal of pterygia (bearing in mind that it could be used as an alternative in some specific cases). Moreover, the beneficial effect of amniotic membrane in the management of ocular surface disorders is still in need of well-designed clinical trials to obtain more solid information. Therefore, clinicians should be judicious when considering AMT applications.