@lyse@lyse.isobeef.org no, as mentioned this “diagonal arrow” eye shape, is usually used for a smug expression. The optional white part, is in this case, where the dogs sclera would be visible, while they have their eyes, like this.
Here is a comparison between a real dog, making the face it is based on, and the exaggerated drawn version.

Thanks, @thecanine@twtxt.net. It’s completely horizontal, I don’t see any diagonals. Anyway, it’s great art, happy drawing!