Eye Guy's upper-body is covered with green eyes and black pupils, although he ironically has no eyes on his face, which consists of a mouth and a very large pair of bat-like ears. He has dark yellow skin with lighter yellow skin on his chest and feet.
In Omniverse, 16 year old Eye Guy looks almost the same as he did in the original series, but now the white stripes on his pants have been replaced with green belts and his main belt is now green with white stripes on the left and right of it. He wears green cuffs and his eye placement is slightly different, and bigger. The pupils of his eyes are now light green instead of black. He has also gained eyes on his palms. He has a green belt where the Omnitrix symbol is located.
11 year old Eye Guy looks the same as the original series, but now has white cuffs, and the Omnitrix symbol on his belt is now green. He also gained eyes on his palms and the different eye placement and pupil color of his 16 year old self.