To begin with, the user's vision is very clear, much more than the Sharingan or the Byakugan. This is because a larger amount of light it taken in by the user's vision. They can see the insects that crawl around on the ground through the grass or even distinguish and see individual raindrops as its raining. They can also see a considerable distance however no where near as far as the Byakugan. Because of the light intake by the user's eyes they are able to see in the dark and jutsu that try to obscure the vision are completely useless against the user.