
In this edition of Foresight we want to explore amniotic membranes. An amniotic membrane is an avascular fetal membrane located within the chorion. It’s harvested in a sterile environment from placental tissue from women during elective cesarean sections. Membrane donors undergo screenings to test for disease and after collective the amniotic membranes are treated with antibiotics.
Benefits of Amniotic Membranes
Amniotic membranes are gaining popularity because of their ability to treat ocular surface problems. They act as a physical barrier, protecting corneal and conjunctival epithelium during the healing process and can reduce pain resulting from friction caused by the patient's eyelids over the surface of the eye. The stromal part of amniotic membranes also helps to prevent fibroblast growth and reduce inflammation through decreased expression of cytokines.
Research is demonstrating that amniotic membranes may have antimicrobial properties and can block angiogenesis. The membranes are universally tolerated due to their lack of histocompatibility antigens HLA-A, B, or DR; so they can be implanted without concern for rejection.
Types of Amniotic Membrane
Two types of amniotic membrane are available for in-office use: cryopreserved and dehydrated. Both types come in a variety of tissue thicknesses and sizes, depending on clinical needs.
Cryopreserved: Involves a slow-rate freezing preservation process that retains the extracellular matrix components that promote anti-inflammatory effects and healing. The tissue is stored in a –80°C freezer until it is needed for use then brought up to room temperature.
The FDA has cleared ProKera (BioTissue) as a class II medical device. The product claims of wound healing and anti-inflammatory effects were also approved. The amniotic membrane requires no assembly and is inserted into the eye through a similar process as a contact lens placement.
Dehydrated Amniotic Membranes: Preserved using a vacuum with low temperature heat to retain devitalized cellular components. To date, FDA-approved claims for this type of membrane are limited to wound coverage.
AmbioDisk (IOP Ophthalmics) is a dehydrated membrane commercially available for in-office use; it is applied directly to the ocular surface and covered with an overlying bandage contact lens.
Patient tolerance to amniotic membranes is generally good which leads us to support the 2015 study conclusion that these membranes can positively impact the treatment of ocular surface diseases.