Preparation and preservation of amniotic membrane

The human amniotic membrane (AM) is the innermost layer of the placenta and consists of a single epithelial layer, a thick basement membrane and an avascular stroma. Due to the number of its properties, AM is increasingly used in the treatment of severe ocular surface diseases. The amniotic basement membrane facilitates migration and growth of epithelial cells, therefore promoting epithelialization. The avascular stroma of the AM reduces fibrovascular ingrowth and abnormal neovascularization. Amniotic epithelium produces anti-inflammatory and growth factors beneficial to the treatment of inflammatory corneal diseases. AM is prepared from a fresh placenta under sterile conditions, washed with balanced salt solution containing penicillin, streptomycin, neomycin and amphotericin B, placed in tissue culture and glycerol at a ratio of 1:1, and stored at -80 degrees C. A donor serological test for human immunodeficiency virus and hepatitis B and C viruses has to be all negative. After transplantation of the amniotic membrane (AMT) onto the eye surface, AM will be slowly absorbed within approximately 4-6 weeks. Depending on consumption, amniotic membranes are used up to 1 year after preparation, although many have recommended storage for an indefinite period. Since AM is not a completely transparent tissue, the patient's visual acuity may decrease after AMT; the patient should be aware of this temporary effect prior to surgery.