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P. G. Soderberg, Y. Zhang, J. Wang, X. Dong, L. Meyer, K. Gallichanin, S. Löfgren; UVR Cataract in Mice, Age Sensitivity. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3259. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate for the C57BL/6 mouse if there is an age dependence of: 1) The dose-response function for in vivo UVR-300 nm induced forward light scattering in the lens. 2) The threshold dose dependence on age for cataract after vivo exposure to UVR-300 nm.
Altogether 25 mice in each of four age groups (3, 6, 12, or 24 weeks), were within each age group 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 (MTD2.3:16). The expected MTD2.3:16 for the 6 weeks old group was set to 3.2 kJ/m2 based on published data. The expected MTDs for the other age groups were estimated to 1.9, 4.8, and 6.0 kJ/m2 for the 3, 12, and 24 weeks mice, respectively, based on a published data for the albino Sprague Dawley rat. The mouse was anesthetized, both pupils were dilated and then the mouse was unilaterally exposed to UVR-B-300 nm to the predetermined dose delivered during 15 minutes. All mice were sacrificed two days after exposure and both lenses were extracted for macroscopic digital photography in incident illumination against a grid and in dark-field illumination. Finally, the intensity of forward light scattering was measured. 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. The sensitivity of the lens to UVR-B was estimated for each age group as MTD2.3:16.
Two days after exposure, subcapsular opacities were observed in the exposed lenses from all dose groups except at 0 kJ/m2. In all age groups, the difference of intensity of forward light scattering increased with increasing UVR-B dose. MTD2.3:16 for avoidance of UVR-B-induced cataract was estimated to 2.0, 3.2, 4.1 and 5.2 kJ/m2 in mice aged 3, 6, 12 and 24 weeks, respectively.
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. Further, the threshold dose for cataract after in vivo exposure to UVR-300 nm increases exponentially declining with age. This finding should be considered in future updates of guidelines for avoidance of cataract after exposure of the eye to UVR.
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