The amniotic membrane is a thin transparent membrane that surrounds the developing fetus of reptiles, birds, and mammals. Amniotic membrane's function is to protect the fetus through ant-inflammatory, anti-scarring, and anti-angiogenic properties. The use of amniotic membranes for wound care has been around since 1910. Currently amniotic membranes are used to treat a variety of ocular conditions including dry eye.
Membranes are obtained from human placentas of consenting donors undergoing cesarean delivery. The use of amniotic membranes for healing is regulated by the American Association of Tissue Banks and the FDA. The membrane and donor are screened for blood borne pathogens. Prior to preserving, the membrane is washed with antibiotics.
There are 2 ways amniotic membranes can be processed for use on the eye.
Dehydrated membranes- sterilized with low energy beam radiation and preserved with a low heat air vacuum.
Cryopreserved membranes- use a proprioratory process to cryopreserve the membrane
Some studies have shown that cryopreserved membranes may contain better healing properties than dehydrated membranes.
Amniotic membranes can help aid in the healing and reconstruction of the ocular surface. They contain ample amounts of bioactive peptides, cytokines, and growth factors which help heal the ocular surface. Amniotic membranes decrease dry eye symptoms by;
Promoting cell growth
Inhibit scar formation
Promote health of nerve cells
Cryopreserved membranes are secured on a flexible round plastic ring which is inserted underneath the upper and lower eyelids after placing a drop of anesthetic in the eye. Membranes are left on the eye for 3-10 days depending on severity of the condition. Occasionally a small piece of tape will be used to keep the eye partially closed for improved comfort. Patients can continue to use eye drops while the membrane is in the eye.
Dehydrated membranes are placed on the anesthetized eye using forceps. The graft is then covered with a bandage contact lens to hold the membrane in place. Membranes are left on the eye for 3-10 days depending on the severity of the condition.