Libera Rodrigo Doyle, Melo Gustavo Barreto de, Lima Acácio de Souza, Haapalainen Edna Freymüller, Cristovam Priscila, Gomes Jose Alvaro Pereira
Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil.
Arq Bras Oftalmol. 2008 Sep-Oct;71(5):669-73. doi: 10.1590/s0004-27492008000500011.
To determine the efficacy of freeze-dried amniotic membrane (AM) for reconstruction of the ocular surface in rabbit eyes.
The sterilized, freeze-dried amniotic membrane (lyophilized or FD-AM) is a preservative method that uses the drying by freezing process to maintain the AM well preserved for a long time even at room temperature. This paper is an experimental animal interventional study. One eye of each of 15 male New Zealand rabbits (1.5 - 3.0 kg) had the central cornea marked with a 6.0 mm trephine. The marked area was deepithelialized with a No.15 blade. The denuded corneal surface was covered as follows: Group 1: cryopreserved AM (n=6); Group 2: freeze-dried AM (n=6); and Group 3: not covered (control group, n=3). The AM in group 1 and 2 and the periphery of the denuded area in group 3 were secured with continuous 10-0 nylon sutures. The clinical evaluation was made by a blinded observer and graded on a four-point scale (1= minimal, 4= marked) for conjunctival and ciliary hyperemia, eyelid edema, corneal neovascularization, corneal opacity and reepithelialization on postoperative (PO) days 1, 7 and 30 . After PO day 30, the rabbits were euthanized and their corneas were sent for histopathological and ultrastructural analysis to evaluate tissue inflammation, reepithelialization, and basement membrane integrity.
Two eyes in group 2 had a corneal infection and were excluded from the analysis. No statistically significant differences among the three groups were found (p>0.05) regarding the clinical evaluation on 1st, 7th and 30th PO days. On transmission electron microscopy, the basement membrane in lyophilized and control groups was more continuous and homogeneous than in the glycerol group.
The freeze-drying method seems to be a good option to preserve human amniotic membrane to be used in ocular surface reconstruction. This preservative method reduces the preservation costs and may enhance the use of AM, facilitating its storage and transport.
确定冻干羊膜（AM）用于兔眼眼表重建的疗效。
经消毒的冻干羊膜（冻干或FD-AM）是一种保存方法，它利用冷冻干燥过程，即使在室温下也能使羊膜长时间良好保存。本文是一项实验动物干预研究。15只雄性新西兰兔（1.5 - 3.0千克），每只兔子的一只眼睛用6.0毫米环钻标记中央角膜。用15号刀片去除标记区域的上皮。裸露的角膜表面覆盖如下：第1组：冷冻保存的羊膜（n = 6）；第2组：冻干羊膜（n = 6）；第3组：不覆盖（对照组，n = 3）。第1组和第2组的羊膜以及第3组裸露区域的周边用连续的10-0尼龙缝线固定。由一名不知情的观察者进行临床评估，并在术后第1、7和30天对结膜和睫状充血、眼睑水肿、角膜新生血管、角膜混浊和上皮化进行四点评分（1 = 轻微，4 = 明显）。术后第30天，对兔子实施安乐死，并将其角膜送去进行组织病理学和超微结构分析，以评估组织炎症、上皮化和基底膜完整性。
第2组有2只眼睛发生角膜感染，被排除在分析之外。在术后第1、7和30天的临床评估中，三组之间未发现统计学上的显著差异（p>0.05）。在透射电子显微镜下，冻干组和对照组的基底膜比甘油组更连续、更均匀。
冷冻干燥法似乎是保存用于眼表重建的人羊膜的一个好选择。这种保存方法降低了保存成本，可能会增加羊膜的使用，便于其储存和运输。
