You might recognize shih-tzus as the dogs that usually have their hair up in a bow. That's not just a cute fashion accessory. You have to pull the dog's hair up, away from the face, because otherwise it covers up their eyes, and they can't see. Either you trim the hair, or pull it back.
Since Luna has a Pomeranian-shaped skull, the hair covers more of her face than it normally would, to the point where her eyebrows sometimes cover her eyes. We try to keep her hair trimmed, but it doesn't always work. As best as we can figure, Luna doesn't see more than three or four feet. If we're playing fetch with her, and the object goes farther than that, she gets confused and can't find it.
Here's a picture of Luna, which kind of shows off the hair on her head covering up one eye. Mostly, the picture shows how her big old whiskers get in the way and make trimming her hair impossible.
Luna, what happened? You don't look so good. pic.twitter.com/k7sMMIMeVU— Michael Gray (@arglefumph) December 2, 2016