Wonderful photo and gorgeous horse. Although, I don't think it's albinism because that would cause red eyes because of the lack of pigment. Are they deaf? Usually animals that are white with blue eyes are deaf...hmmm...
Blue-eyed horses are often descended from the original Spanish Mustangs, though random recessive genes could also be the case. There's a great many blue-eyed horses at the Wild Horse Preserve by Hot Springs, SD, that are known to be be Spanish Mustang descendants.
Anyways, wonderful photo!