Thank you for all your answers!

So, we could theorize that blindness in FFXIV can come from the same reasons or consequences as IRL, as illnesses, birth defects, injuries, and we could probably add some magical/aether discharge accidents in the mix, but otherwise it seems quite a standard condition then. Would a healer be able to do anything about it?
It seems through the lore I've read, that most handicaps can't be fixed through healing if they're old or serious enough (incapacitated or cut limbs, deep scars and so on), but just to be sure...