When standard optical glass is subject to radiation it causes severe darkening (browning), resulting in almost total transmission loss. To stabilize optical glass against transmittance loss the composition is doped with cerium oxide (CeO₂). Cerium oxide acts as a stabilising agent, preventing the darkening. A lens produced from non-browning glass will continue to work until it has exceeded its accumulative dose of radiation. In the case of Resolve Optics radiation resistant lenses – they are rated for 100,000,000 rad – so depending on the level of radiation they are exposed to daily you could expect a lens to have a life of around 10 years.
Learn more: https://www.resolveoptics.com/selecting-a-lens/
