The Effects of Tween 20 onin vitroBovine Lenses

Abstract

The optical properties of the cultured bovine lens were analyzed after exposure to various concentrations of Tween 20, a nonionic surfactant, to find a nonirritating concentration for commercial products. Bovine lenses were extracted and placed into a culture chamber for 24 hours at 37 C with 4-5% CO 2 . The lenses were placed into three treatment (1%, n ¼ 10; 10%, n ¼ 9; and 100%, n ¼ 10 Tween 20) and one control group (n ¼ 7) for 15 minutes. For 8 days following treatment, the lens optics were analyzed periodically for back vertex distance (focal length) and back vertex distance variability (sharpness of focus) using a laser-scanning device. For both the control and the 1% Tween 20 condition, no significant change was seen from the beginning of the experiment (p > 0.05). The 10% Tween 20 solution induced significant loss of sharp focus (0.62 AE 0.1 mm SEM) 4 hours after exposure, increasing to BVD ¼ 1.69 AE 0.3 mm SEM by the end of experimentation (p < 0.05). At full strength (100%), Tween 20 began to cause damage after 4 hours (BVD ¼ 0.50 AE 0.06 mm SEM), and this change increased to BVD ¼ 4.46 AE 0.59 mm SEM after 8 days following treatment (p < 0.05). Therefore, a dose-dependant increase in back vertex distance (BVD) variability was detected. This research suggests that using 1% Tween 20 in commercial solutions should not produce ocular irritation, whereas concentrations above 10% will cause significant irritation. As well, the bovine lens assay, paired with the automated lens scanner, provided a sensitive approach to measure mild ocular irritation.