It all depends on the material you use for the eyes and the eye placement.
I use a very fine chiffon fabric for my eyes and it works very well, you can even read when in suit but you cannot see in from the outside. Other options would be buckram, sun glasses lenses, wire mesh and plastic canvas. All of them have their advantages and disadvantages
The placement of the eyes in the suit can make alot of difference as well. Putting the eyes closer together will eliminate the 'blind spot' in the center of your vision but this can make the suit look unnatural having them too close together. How the suit is built can make all the difference as well. The closer the fursuit eyes are to your actualy eyes the wider your field of vision and the easier it is to see.
The muzzle on your suit can also mess with your vision because you cannot see below them, so you have to tilt your head down to see the ground or small children.
The more you wear the head your eyes will adjust and you will get used to what you have to do to see out of it and move around safely.
And you should always have a handler that is out of suit walking with you to look out for obstacles like stairs, cars, and children etc to make sure you dont hurt yourself or anyone else
