I wouldn't worry too much about that. I don't know where that thing comes from that it has to also be with one eye. Astigmatism isn't necessarily in every eye. My left eye has it worse than my right eye. So if I were to try and look with one eye, I'm sure it would be worse with my left than my right. I don't know what the one eye thing is supposed to mean without more context, but your two eyes are never the same.