Why does Yi have goggles for 7 eyes?

The goggles? Just for reading.

He has 2 eyes, just like the most of the humans.

I always assumed each lens ha a different function. Thermal imaging, electromagnetic spectrum, probably something hextech/magic-y.

He has two eyes. The googles allow him to see in different angles. Good for killing, and making the best salads.

So he can Q.

So he can see really, really well.