Effect of age on ocular irritancy as measured with in vitro bovine lenses

This project studied the effect of age on optical quality of cultured bovine lenses exposed to a number of common surfactants and alcohol.

Lenses from calves (8-18 months) and cows (2-3 years) were isolated aseptically and studied optically for 96 h after treatment with various commercial surfactants and an alcohol. Potential eye irritancy was evaluated using a scanning laser in vitro assay system which records the change in focal characteristics (back vertex distance variability or BVDV) of the bovine lenses. Lenses were divided into a total of 14 groups. Both calf and cow lenses (a total of 257 lenses were used) were arranged into control, 0.01% BAK, 1% SDS, 1.0% Triton X-100, 100% ethanol, 10% Tween-20 and 1.0% Tween-20 treatment groups.

The cationic surfactant BAK caused the most amount of optical change to the bovine lenses, followed by SDS, Triton X-100, ethanol and then Tween-20. There was also a significant difference in BVDV between the cow and calf groups for all the treated groups, except for Tween-20, with the calf lenses showing greater optical damage. In the case of 10% Tween-20, both cow and calf lenses show equal optical damage while at 1.0% both groups show no effect and are no different from the untreated control lenses.

Younger bovine lenses are more sensitive to the surfactants and alcohol tested when compared to their older counterparts, indicating that younger eyes may be more sensitive to these chemicals. The results further indicate that age is a factor that should be taken into account in assessing ocular risk.