We have evaluated a new in vitro opacitometer method as an alternative to the in vivo Draize test for ocular irritancy. Several concentrations of timolol maleate (timolol) with or without 0.005% benzalkonium chloride were applied to porcine isolated corneas which were either intact or with the epithelium, endothelium, or both epithelium and endothelium removed. Corneal opacities were measured using an opacitometer. In general, timolol with benzalkonium chloride caused a greater degree of opacity to develop in the cornea than did timolol alone. At the lower concentrations of timolol, the increased opacity probably represented additive effects of the two compounds. However, at the highest concentration of timolol (5 x 10 2M), there was an enhanced opacification in the presence of benzalkonium chloride, which may have been due to an increase in penetration, particularly through the epithelium. Timolol caused a greater degree of opacity to develop in the isolated intact porcine corneas when the drug was applied to the endothelial surface, than when applied to the epithelial surface or to both the epithelial and endothelial surfaces. However, timolol with benzalkonium chloride caused a greater degree of opacity in the intact cornea, when the drug was applied to both surfaces than when it was applied only to the epithelial or the endothelial surface.

中文翻译：

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使用透光度计比较含有和不含苯扎氯铵的噻吗洛尔的体外角膜混浊效果

我们评估了一种新的体外透光度计方法，作为体内 Draize 眼刺激试验的替代方法。将含有或不含 0.005% 苯扎氯铵的几种浓度的马来酸噻吗洛尔 (timolol) 应用于分离的猪角膜，这些角膜要么完整，要么上皮、内皮或上皮和内皮均被去除。使用不透光度计测量角膜不透明度。一般而言，噻吗洛尔与苯扎氯铵相比，单独使用噻吗洛尔会导致角膜中出现更大程度的混浊。在噻吗洛尔浓度较低时，增加的不透明度可能代表两种化合物的叠加效应。然而，在噻吗洛尔的最高浓度 (5 x 10 2M) 下，在苯扎氯铵的存在下，不透明性增强，这可能是由于渗透增加，特别是通过上皮。与应用于上皮表面或同时应用于上皮和内皮表面相比，当将药物应用于内皮表面时，噻吗洛尔在分离的完整猪角膜中产生更大程度的混浊。然而，当将药物应用于两个表面时，与仅应用于上皮或内皮表面时相比，噻吗洛尔和苯扎氯铵会导致完整角膜中更大程度的混浊。