i saw in some video that it was because of an injury in a fight and he had to get surgery on it. still resulted in a permanent scratch in his eye.
so says wiki
"He then faced Japanese star Hayato Sakurai, who would go on to win in a fast paced see-saw affair that showcased both the toughness and heart of Pulver, and the experience and technicality of Sakurai. During the fight Pulver was accidentally thumbed in the eye by Sakurai, which left a corneal abrasion on his eye. During the fight Pulver can be seen repeatedly rubbing his eye and wincing in pain. Despite being temporarily blinded in one eye, Pulver nearly knocked out Sakurai with a left hook in the latter part of the first round. "