For this tutorial I'm going to focus on fixing this gentleman's right eye. As you can see there is a tear that runs directly over his right eye. I'll try to repair the right eye by using the left eye.
Use the eyedropper tool to select a shade of gray from the nose. Then select the paintbrush tool, changing its mode to Lighten with a fairly low opacity
With a couple strokes of the paintbrush, the shadows around the nose look a lot better and the eye repair is complete!