Eyes are the most important thing for a human being....people say, "dari mata turun ke hati..cheewah!". So does a cartoon feel...mcm hidup plak. Regardless using Photoshop brush or barely hand-drawing, simple dots may represent what kind of mood each cartoon character is portraying.
With that, I would say...different eyes represent different expressions in cartoons, caricatures, or doodles.
These are the examples of the simplest eyes with simple dots, by just adding lines….
HoW tO DrAw these EyES usiNg AdoBe PhOTosHop (for beginners):