Berachos 25a - Part II

I wrote in a previous post: "What I'm wondering is: A person with eyeglasses or contact lenses - what is considered normal vision for him? Is it as far as he usually sees (in other words, as far as he sees while wearing glasses), or, as far as he naturally sees?" In that post we discussed the Halachic ramifications of the question. Two new points:
1) On Friday night I had the pleasure of attending the Shalom Zachor of a good friend. His brother-in-law, an anonymous attorney from Manhattan, suggested the following answer: When one is wearing glasses, his vision is considered to be how far he can see while he has glasses on, while if his glasses are off, then his vision is considered as far as he can see with them off. Based on this, the same person will have a different status in halacha depending if he is wearing glasses or not. I'm not sure if he's right, but it certainly is worth thinking about.
2) As far as what the distance of one's vision is, obviously it depends on the individual person's eyesight. However, to give us an idea of a minimum in the times of Chazal, see the gemara on 33a: "Rabbi Oyshia learned: One should distance himself fifty amos [even] from a docile ox, and from an ox with a history of goring, as far as one can see." We see from here that the amount of one's vision was more than fifty amos. (However, one could differentiate by saying that the gemara on 33a is talking about an ox, which is much bigger, and therefore more visible even at a longer distance - while in our gemara, where we're talking about unclean items which may be very small, the distance of one's vision is considered less than fifty amos.)