Cryopreserved amniotic membrane (Bio-tissue, Miami, FL www.biotissue.com) can be used either as a Permanent Graft, a Biologic Bandage, or both
|Permanent Graft||Biologic Bandage|
|What biologic action(s) are primarily delivered?||Anti-inflammatory, anti-scarring, anti-angiogenic, and growth promotion||Anti-inflammatory and growth promotion|
|Where does the epithelialization occur?||Over the membrane||Under the membrane|
|Will the membrane be integrated into the host tissue?||Yes
(either conjunctiva or cornea)
|Will the membrane be removed/dissolve?||No||Yes. After healing the tissue will dissolve or be removed. Rapid dissolution in less than one week suggests an “exposure” problem|
|How many layers are needed?||One or multiple layers to fill in stromal defects of any shape||One|
|Does the orientation matter?||Yes
(stromal/sticky side down for the top layer)
|Do I need to use sutures?||Fibrin glue or sutures can be used to secure the graft (if multiple layers are used, the top layer must be sutured)||10-0 nylon sutures by purse-string perilimbal or running otherwise|
Differences in cryopreserved Amniotic Membrane Delivery Methods
|Surgically Attached Layers
|Mode of use||Permanent graft or biologic bandage||Biologic bandage only|
|Treated area||Cornea, conjunctiva or both||Cornia only|
|Depth of defect||Superficial or deep||Superficial only|
|Number of layers needed||Single or multiple||Single only|
|Sutures used?||Yes (sutures or fabrin glue needed)||No|
Surgical Handling of Cryopreserved Amniotic Membrane
Cryopreserved amniotic membrane is semi-transparent and is resilient to stretching or tearing. To help orient the membrane during clinical use, the tissue’s sticky stromal side is manufactured attached to the carrier paper. This carrier paper is enclosed in a dualpouch system (A) and shipped in a temperature controlled shipping container.
In the operating room, the circulating nurse peels open the foil pouch (B), while the scrub nurse retrieves a clear plastic bag from inside using sterile smooth forceps or gloves to remove the inner pouch containing the tissue (C). The clear inner pouch may be introduced to the sterile field. Using sterile scissors, cut below the sealed line of the inner pouch and remove the tissue and carrier paper using smooth sterile forceps (D).
Removing Cryopreserved Amniotic Membrane from the Carrier Paper
During surgery, the orientation of AmnioGraft® should be “the sticky stromal side down” if it is used as a permanent graft. If multiple layers are used, the orientation of the bottom layer(s) does not matter; only the orientation of the top membrane needs to be “sticky stromal side down”. The following methods can be used to ensure such an orientation.
If an assistant is available, the surgeon may use two 0.12 forceps to grab the two corners of the membrane while the assistant retrieves the backing support from the surgeon (E). By keeping the two forceps apart, the surgeon can ensure that the sticky stromal side (facing the backing support) is placed down on the area to be grafted.
If an assistant is not available, the surgeon may use one 0.12 forceps to grab the backing support while a dry surgical sponge or 0.12 forceps are used to peel off the membrane gradually from one side until 3 to 5 mm of the remaining membrane is still adhered to the backing support. The backing paper is then flipped so that the membrane is underneath and the semi-detached membrane is flattened on the eye. This ensures the sticky stromal side is facing down on the area to be grafted.
Confirming Amniotic Membrane Orientation
If the orientation becomes questionable, the following method can be used to verify the desired orientation:
(Video link doesn’t work)