Perhaps if you could fix the blindness, that is one decision. But that isn't really what we are talking about. If termination is the option then what we are doing, essentially, is looking at all those who are congenitally blind and saying - this world would be better if a different, sighted, person existed instead of you.
Thematically, this is the same as scenarios involving prophylactic usage amongst teen women and their partners. We're then looking at those born to teenage mothers and saying "this world would be better if a different, younger, person existed instead of you".
I don't agree with the reasonings. I don't think that discouraging teenage pregnancies is the same thing as disparaging those born to such unions. It IS close, in some ways, but it's not the same.