Some creatures have eyes that suit their situation.
If they live in muddy rivers, or caves, then eyesight isn't worth much. But for many, better eyesight creates opportunities. It might let a bird fly a bit faster through a forest, or let a bee see distant flowers on a slightly cloudier day. It might give a deer more warning of a predator, or of quicksand, or of brambles. It would let a male elk watch a bigger harem for strays and interlopers.