None of the in vitro method are suitable for directly classifying of a substance as an eye irritant (category 2). They can classify substance as category 1 (serious eye damage) or as "no category" (not requiring classification). The aim of this study was to develop a new method for direct classification of a substance as category 2. Cytotoxicity Assay to Assess Eye Irritation (CEI) was performed on fibroblast - HDFn cell line with 36 substances. 5 concentrations of all substances and neat substances were applied directly to the cells. After 30 minutes, medium was added and cells were incubated at 37 °C. The next day, the cytotoxicity assay was performed (MTT assay in the first run and NRU assay in the second run). Based on viability and IC50 value (concentration with 50% viability) a substance could be classified in category 2, category 1, and as "no category". The results obtained were referred to ECHA database. This new method had high sensitivity (53.8-88.9%), specificity (73.9-100.0%) and accuracy (69.4-88.9%) in the classification to all categories. It effectively classifies not only substances in category 2 but also in category 1 and substances that do not require classification.

中文翻译：

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一种通过细胞毒性试验直接分类眼刺激物的新体外方法的提案 - 初步研究

没有一种体外方法适合将物质直接归类为眼刺激物（第 2 类）。他们可以将物质分类为第 1 类（严重眼损伤）或“无类别”（不需要分类）。本研究的目的是开发一种将物质直接分类为第 2 类的新方法。对具有 36 种物质的成纤维细胞 - HDFn 细胞系进行细胞毒性测定以评估眼刺激 (CEI)。将 5 个浓度的所有物质和纯物质直接应用于细胞。30 分钟后，加入培养基并将细胞在 37°C 下孵育。第二天，进行细胞毒性测定（第一次运行中的 MTT 测定和第二次运行中的 NRU 测定）。根据存活率和 IC50 值（50% 存活率的浓度），物质可归为第 2 类，类别 1，并作为“无类别”。所得结果参考ECHA数据库。这种新方法在对所有类别的分类中具有高灵敏度（53.8-88.9%）、特异性（73.9-100.0%）和准确度（69.4-88.9%）。它不仅有效地对第 2 类物质进行分类，还有效地对第 1 类物质和不需要分类的物质进行分类。