UltraDot clarity

I realized when looking thru my son's new UD that the lenses on my old UD's were not nearly as clear as new.  Mine have been on my bullseye pistols for years and over time, I did not realize how much haze I was looking thru.  They are certainly useable, but I wish they were clearer.  The exterior lenses are clean so the haze must be within.  Is this just something to live with or can it be corrected?
Thanks
Phil

If there is a haze on the inside, I would assume a seal has failed and it is time for a service visit.