The eyes of a zombie, despite of a few physical deterioration, is technically the same as a human’s in both function and quality.
Zombies have a very good sense of smell. They can detect living prey above all other beings. They can smell flesh from over a mile away. It is the same as a human’s but became more reliable because of it’s importance.
Zombies have excellent hearing. They can detect and determine the direction of any sound. They are attracted to every sound that they hear, even the littlest of sounds we humans take for granted.
(Pictures and information credited to Max Brooks)