Your best bet is to have a vet evaluate the horse and tell you the long-term prognosis.
Uveitis (moon blindness), if that is what the horse has, affects appaloosas which do not generally have blue eyes that I know of, so blue eyes do NOT cause a horse to have more eye problems.
The horses that I know of that have Uveitis have to wear face masks and some even have special masks with filters for the eyes. I know one lady that worked for over 2 years to get her mare treated. She uses the mare for light trail riding and the mare has to wear the mask with eye filters all the time.
Another horse, a halfinger, is a pasture pet and wears his mask with eye filters all the time.
There are rescues that have blind horses. The blind horses are paired with one other horse who wears a bell that the blind horse can follow.
There's a lot of good horses out there. I suggest that you keep looking.