Cryopreserved Amniotic Membrane in Fornix Reconstruction Surgery
By Dane Slentz, MD
Overview of Fornix Reconstruction
The fornix is a redundant area of the conjunctiva that has an important function in ocular motility. The depth of the conjunctival fornix allows the eyelid to oppose the surface of the eye for optimal movement, and it maintains a position that is high enough on the eyelid to protect the eye. Shallow fornices may cause the eyelid to retract, which can lead to significant ocular surface dryness. Additional complications can cause the eyelid to either turn in (entropion) or turn out (ectropion). In patients with an anophthalmic socket, fornix depth directly affects prosthetic fit and whether the eyelids are able to fully close.
Fornix reconstruction can help manage cicatrizing disorders such as Stevens-Johnson Syndrome, ocular cicatricial pemphigoid, and trachoma, in addition to scarring secondary to trauma and burns. Significant scarring from previous surgical procedures involving the fornices, including orbital fracture repair, can lead to a shortened fornix that may require reconstruction. When considering grafts, the healing properties associated with amniotic membrane (AM) make it a beneficial choice for conditions involving forniceal scarring.
Challenges with Fornix Reconstruction
Improper positioning of an ocular prosthesis in fornix reconstruction can make a sizable impact on a patient’s quality of life. It is important to ensure that a prosthetic is fit comfortably, and it’s also crucial to consider the cosmetic result. An ill-fitting prosthetic could have a noticeably different appearance than the other side, which could have a social impact for patients. Patients are generally happier with a more natural-appearing eye, and a successful surgery will result in fewer ocular symptoms with an improved quality of life.
Following fornix reconstruction, the most common post-surgical complication is excessive scarring. Excessive scarring of conjunctival tissues can cause the prosthesis to deviate. While infection, excessive bleeding, and harm to the eye represent other considerable risks, scarring in the inferior fornix is noteworthy for the potential to cause shortening.
Experience with Cryopreserved Amniotic Membrane
Amniotic membrane has served as a very good and useful substrate graft with fornix reconstruction. The graft succeeds in providing lengthening and augmentation of the inferior fornix to help achieve a better position. After a scar is released, the AM graft creates more space and contains essential nutrients and biological factors that help to reduce scarring at the end, which is an important outcome for the patient.
While both dehydrated and cryopreserved AM (CAM) have demonstrated encouraging results with regard to overall healing properties, my experience with CAM (AmnioGraft; BioTissue) has been favorable, in part, due to its unique material properties. Owing to its thickness, CAM does not tear easily, so it is easier to work with in surgery. Whereas dehydrated AM requires a longer time to rehydrate, CAM is fully hydrated at first use and feels like it has more tensile strength. The overall ease of handling is a remarkable benefit, as it makes the surgery easier to perform and helps facilitate positive outcomes, as it has shown to be well-tolerated by patients.
Developments in Technique
Over time, there have been adjustments in the surgical technique of fornix reconstruction. Sutures were initially used to secure the AM, and sutures are still sometimes necessary. Our practice has also begun to use thrombin-based glue, which does not cause additional inflammation, bypasses the need for another stitch, and potentially helps to promote overall healing. While one technique may serve one patient well, the same method may not work well for another, so the decisions must be made case-by-case. Moreover, though sizing is standardized, the AM is often tailored to the defect for a better fit. It’s critical to remember that the fornix is redundant.
Ideal candidates for fornix reconstruction with CAM transplantation would include anophthalmic patients with a shortened fornix and a prosthetic that cannot be further adjusted by an ocularist. Additionally, CAM has worked very well in providing healing in cases of exposed orbital implants.
Dr Slentz discloses he is a speaker for Horizon Therapeutics.
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