suma kasher ladun?

The gemara in nidda 49b-50a assumes that a person who is blind in both his eyes is not allowed to testify (Tosafos Harosh points out that this is even if he's testifying on something he saw before he became blind). The gemara then says that it's a machlokes tannaim about whether a suma can judge. The gemara says clearly that according to R' Meir a person who is blind in one eye can testify but cannot judge. The gemara says that the Chachamim argue and hold that a blind person can judge. I think that the simple reading of the gemara is that the machlokes is about someone who is blind in one eye but if he's blind in two eyes then everyone would agree that he can neither judge nor testify. However, I was surprised that Tosafos says that the Chachamim hold that someone who is blind in both eyes could judge but cannot testify. So it's a machlokes mikatze lakatze.

UPDATE (3:30 PM) I just looked up the Rambam and he argues with Tosafos. He paskens that someone who is blind in one eye can judge but not someone who is blind in both eyes. Hagaos Maymoniis asks that this seems to contradict our gemara but the Kesef Mishna points out that it doesn't necessarily contradict it if he doesn't learn like Tosafos. From the simple reading of our gemara, the Chachamim only argue by a person blind in one eye but everyone agrees that someone who is blind in both eyes cannot judge.