With true split lighting, the only light on the shadow side of the face is the catch light in that eye, but there are variations that result in a softer light that falls more on the shadow side of the face.
As the name implies, it splits the face into equal halves, with one side being in the light and the other side being in the shadow. It tends to be used more with men rather than women because it creates more dramatic, masculine-appearing images. With true split lighting, the only light on the shadow side of the face is the catch light in that eye, but there are variations that result in a softer light that falls more on the shadow side of the face.