Good vision is less necessary for hunting than you might think. One common hunting role is simply to walk though an area while making a lot of noise. Abstractly large numbers of people have poor vision in large part because our ancestors could get by with poor vision. Traps and fishing are other examples with minimal requirements in terms of vision.

Remember, hunter gathers don't need to read tiny text, or the pattern of bark on a tree. So, even what we think of as poor vision was actually often 'good enough'.