I would not get concerned about what someone says about a photo...does your chihuahua have any symptoms of neurological distress ?
My Zari has what some people deemed to be " east -west "eyes and she does not have hydrocephalus...
Go to your vet and get a professional opinion...not one from a forum or photos and then you can relax and enjoy your little Forrset.
He looks fine to me, Ike was not real playful when he was real young like Forrest. He is now 6 months old and a terror. Forrest is still a very young baby. I think Forrest is just adorable. He is so cute. Is he still eating okay?