We have a Zuchon (actually Mrs. C has the dog) which is a Shih-Tzu/Bichon Frisse cross. We have working dogsd here on the ranch in western U.S., and I didn't take readily to the little white dog. But... I won't admit it to Mrs. C, but the little white dog is probably the smartest dog I've been around. They are super hard headed and even house training was a fight "royale".
As to your question, I noticed the same thing. Firstly, I was surprised that on walks, especially, the dog is a "nose" or scent dog... nose buried in everything and plants feet and resists pulling the leash when something really stinky gets her attention. I noticed that the right eye looks askance when she's looking directily at you and there's white showing around the inside edge even when looking straight ahead. Our Vet and some breeders of small dogs I know have both stated that, due to the "skrunched" up face, the dogs often have sight problems, which is one reason they rely so much on thier nose. Nothing one could do about it really, (laser eye surgery for dogs? Not!)... and like many other things they just compensate...