They had macular degeneration which usually can be slowed down or stopped while there's a bit of vision left. Now they're at "no light perception". Considerably worse.
Sure, it only lasts a couple of years. But, when you are 80+ years old, that may be all you need.
My mother has macular degeneration and the only thing they even said was possible so far is injections with Eylea, Lucentis or Macugen.
I guess she manages currently, but it's interesting to see that there are other options