In the older groups the severity of cataract had increased as compared to one week post-exposure. Discussion Younger rats developed more severe cataract. This is new information which not has been taken into consideration when current safety limits for UVR exposure was established. It may also have implications in ophthalmic laser treatment in children. There are some factors which we believe may explain this.
Young rats have a shorter depth of the anterior chamber than older rats.
The lens size increase with aging. Therefore, in a young animal the UV radiation will reach deeper, relatively, into the lens compared to a older, and larger, lens. The transmittance of UV-B radiation is higher in young lenses. Larger volume of the lenses will then be reached by the radiation. The cell division rate is higher in younger rats.