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What we've learned about amniotic membrane
Amniotic membrane has been in use in ophthalmology for over 30 years to reconstruct defects of the conjunctiva and cornea when severe disease depletes a healthy surface. In my practice, where we perform about 200 procedures with amniotic membrane each year, we've learned some important truths about this useful material:
1. Amniotic membrane has powerful anti-inflammatory and antifibrotic effects.
Whether used to treat a non-healing defect on an inflamed cornea, to resurface the globe after pterygium excision or as a subconjunctival implant to prevent pterygium recurrence, this simple collagen material has a remarkable capacity to modulate the healing and inflammatory response. As such, it deserves an important place in ocular surface surgery, and surgeons who perform these procedures should become familiar with its benefits and use.
2. Both freeze-dried and cryopreserved amniotic membrane have similar biologic effects.
Different companies, such as Bio-Tissue and IOP Ophthalmics, prepare amniotic membrane in different ways, and some surgeons prefer one thickness or variety over another. However, in my experience with hundreds of cases using all types of material,
I have seen no significant difference in the behavior of these materials.
3. If you currently perform pterygium surgery leaving bare sclera, you will get better results by grafting with amniotic membrane.
This simple technique causes less pain and far less inflammation than bare sclera surgery, and recurrences range from 50% to about 5%. Using fibrin glue to secure the amniotic membrane is an easy technique to adopt by anyone performing this procedure. A step-by-step video guide to performing this procedure can be found here.
4. If you currently perform pterygium surgery with a conjunctival autograft, using adjunctive subconjunctival amniotic membrane can help you further reduce recurrence.
Placing the amniotic membrane in the subconjunctival space surrounding the pterygium excision as an implant (in the same location where we would apply mitomycin C) allows less fibrosis after surgery and clearly less recurrence in my experience of about 500 cases. A video describing this technique can be found here.
5. New applications of amniotic membrane will change the way we treat ocular surface conditions.
Development of new onlay grafts and even eye drops composed of homogenized amniotic membrane will allow us a new approach to performing extraocular surgery that will speed healing, improve comfort and avoid scar tissue in the not-too-distant future. I very much look forward to using these new technologies for challenging ocular surface conditions as they become available.
- Disclosure: Dr. Hovanesian is a consultant to IOP Ophthalmics, producer of AmbioDry products, and receives funding for research from Bio-Tissue, producer of AmnioGraft products.