@awnlee jawkingSome things to consider.
Ionizing radiation comes in two main flavors. One particulate and the other EMF. Contamination is ionizing particles where they are not desired. Some stronger particles put out some EMF as well.
Alpha - particle
Beta - particle
X-ray - EMF
Gamma - EMF
Neutron - particle
Alpha and beta particles can damage external body parts, and if internalized by various means, they can damage internal organs.
A Neutron particle is a different beast. It's the highest energy level typically involved. Of the five mentioned, it's the only one that can make something radioactive that wasn't previously so. Internalizing alpha and beta particles can destroy cells in the body, but they cannot make them radioactive themselves.
Gamma and X-ray typically are only differentiated by their source and most times their energy level. X-rays are usually weaker and for people, generated by a machine. Gamma comes from one or another isotope or nuclear process (see photosynthesis, compton scattering, pair production, and fusion).
UV, while in the electromagnetic spectrum like gamma, is not considered an ionizing radiation as it does not have the energy to affect any subatomic particle (electron for instance). Yet it does have the energy to affect various chemical compounds, deoxyribonucleic acid for instance (DNA). The difference between damage done by ionizing radiation verses none ionizing radiation is one works on a subatomic scale, and the other on an exothermic/atomic scale. Both damage DNA by different means.
The matter that comprises the eye can be damaged by any of the above.
However, light colored eyes have less pigmentation in them. That makes them more susceptible to UV damage in general.
Based on your description, the blue eyes would have been a retro mutation. Conflating the damage vectors can cause confusion.