Amniotic Membrane Transplant

The first amniotic membrane transplant in ophthalmology was performed in 1940 with partial success in the treatment for conjunctival epithelial defect. There with little else done with amniotic membranes until the 1990s. Amniotic membranes were used for the ocular surface reconstruction on severely damaged corneas in a rabbit model. Since then amniotic membranes have been used for a number of different conditions.

The normal ocular surface is made up of corneal, limbal and conjunctival epithelial cells. The limbal stem cells are important in that they are necessary to maintain a smooth and clear corneal surface. These cells in combination with the tear film work together to make the ocular surface healthy which allows for strong visual acuity. Damage to these cells from diseases or trauma may cause trauma to the normal corneal epithelial. The results can cause a number of conditions on the cornea which eventually will lead to poor visual acuity.

The exact mechanisms used by the amniotic membrane to treat the ocular surface are still largely unknown. Doctors are still trying to evaluate if the amniotic membranes are related to limbal stem cell proliferation or epithelialization of the corneal surface. The structure and presence of growth helps to grow the epithelial tissue on the cornea.

When it comes to having an amniotic membrane transplant there are two types of techniques used to perform the procedure. The Inlay technique plays the amniotic membrane graft into the corneal ulcer, then is secured by sutures without extending past the defect in the epithelial. Studies have shown that when this type of technique is used the amniotic membrane acts a basement membrane. However, using this technique may limit corneal transparency for several months after surgery and could affect the vision.
 
The overlay technique involves the entire corneal surface including the limbus being covered with the amniotic membrane graft. The amniotic membrane functions as a contact lens. The graft will protect the epithelium that is regenerating from the friction caused by the eyelid and palpebral conjunctiva but it will still allow oxygen and moisture reach the epithelium. The transparency of the corneal will remain when the graft eventually detaches or dissolves. Both the inlay and overlay techniques may be used together for medical treatments.

In the field of ophthalmology the used of amniotic membrane for transplants are many. The rediscovery of its use can greatly improve the treatment of ocular surface diseases. Studies are continually being performed to determine new uses for the amniotic membrane on the corneal surface. Amniotic membrane transplants may be the answer to cure for a number of ocular diseases.