School of Pharmacy, University of Reading, Rm 108, Hopkins Building Whiteknights, PO Box 228, Reading RG6 6UB, UK.
Br J Ophthalmol. 2010 Aug;94(8):1057-61. doi: 10.1136/bjo.2008.153064. Epub 2009 Mar 19.
BACKGROUND/AIMS: Scant consideration has been given to the variation in structure of the human amniotic membrane (AM) at source or to the significance such differences might have on its clinical transparency. Therefore, we applied our experience of quantifying corneal transparency to AM.
Following elective caesarean, AM from areas of the fetal sac distal and proximal (ie, adjacent) to the placenta was compared with freeze-dried AM. The transmission of light through the AM samples was quantified spectrophotometrically; also, tissue thickness was measured by light microscopy and refractive index by refractometry.
Freeze-dried and freeze-thawed AM samples distal and proximal to the placenta differed significantly in thickness, percentage transmission of visible light and refractive index. The thinnest tissue (freeze-dried AM) had the highest transmission spectra. The thickest tissue (freeze-thawed AM proximal to the placenta) had the highest refractive index. Using the direct summation of fields method to predict transparency from an equivalent thickness of corneal tissue, AM was found to be up to 85% as transparent as human cornea.
When preparing AM for ocular surface reconstruction within the visual field, consideration should be given to its original location from within the fetal sac and its method of preservation, as either can influence corneal transparency.
背景/目的：人们很少关注人羊膜（AM）在来源处的结构变化，也很少关注这些差异对其临床透明度可能产生的影响。因此，我们将定量评估角膜透明度的经验应用于 AM。
在选择性剖宫产术后，比较了胎儿囊远侧和近侧（即毗邻胎盘处）的 AM 与冻干 AM。通过分光光度法定量评估 AM 样本的透光率；通过光学显微镜测量组织厚度，通过折射仪测量折射率。
胎盘远侧和近侧的冻干和冻融 AM 样本在厚度、可见光透过率和折射率方面存在显著差异。最薄的组织（冻干 AM）具有最高的透光率谱。最厚的组织（胎盘近侧的冻融 AM）具有最高的折射率。使用角膜组织等效厚度的直接求和场法预测透明度，发现 AM 的透光率高达 85%，与人眼角膜相当。
在视野内为眼表面重建准备 AM 时，应考虑其在胎儿囊内的原始位置及其保存方法，因为这两者都可能影响角膜透明度。
