[aristus]

I think you got your signs reversed. The spider in question has extremely good vision.

"Jumping spiders already have excellent vision and Portia’s is ten times as good, making it sharper than most mammals."

[pmelendez]

I don't know if the parent post was edited but it does state right now:

"The story is a little different in the case of Portia, given that they are apparently at a visual advantage to their prey. "