Age dependence of cataract induced by ultraviolet radiation-B in mice

Purpose: To investigate for the C57BL/6 mouse if there is an age dependence of the dose‐response function for in vivo UVR‐300 nm induced forward light scattering in the lens. Methods: Each of four age groups of 25 mice aged 3, 6, 12, or 24 weeks were randomly distributed on five age group specific UVR‐B dose levels. The dose levels selected for each age group were derived from the expected maximum tolerable dose (MTD). Expected MTDs were set to 1.9, 3.2, 4.8, and 6.0 kJ/m^2 for the 3, 12, and 24 weeks mice, respectively, based on published data for the albino Sprague Dawley rat. Each animal was unilaterally exposed to UVR‐B to the pre‐determined dose, delivered during 15 minutes. All mice were sacrificed two days after exposure and both lenses were extracted for; macroscopic imaging in incident illumination against a grid and in dark‐field illumination, and measurement of intensity of forward light scattering. The difference of intensity of forward light scattering between the exposed and the contralateral not exposed lens was fitted against dose received using regression based on a second order polynomial model. Results: Two days after exposure, subcapsular opacities were observed in the exposed lenses from all dose groups except at 0 kJ/m^2. In all age groups, the difference of intensity of forward light scattering increased with increasing UVR‐B dose. The increase was age dependent. Conclusions: In the pigmented C57BL/6 mouse, an increasing in vivo dose of UVR‐300 nm induces an increasing intensity of forward light scattering that is age dependent in the age interval 3‐24 weeks. This finding should be considered in future design of experiments on UVR‐effects to the mouse lens.