There are various places to focus the eyes, depending upon the meridians and parts of the brain to be stimulated.
Third Eye Point (Sixth Chakra): This is our default gaze in Kundalini Yoga and turns your attention inward. To practice, close the eyes and gently focus to the Brow Point, at the center of the forehead, a little above the eyebrows. This gaze stimulates the pituitary gland and sushmuna (central nerve channel of the spine), and develops intuition.
Tip of the Nose: Relax the eyes and look at the tip of the nose. This gaze is uplifting, balances the ida, pingala, and sushmuna (left, right and central nerve channels of the spine), stimulates the pineal gland and frontal lobe of the brain, and creates new energy pathways and neural circuits in the brain.
Tip of the Chin (Moon Center): Closed eyes are focused downwards to the center of the chin. This location corresponds to the Moon Center. This produces a calming and cooling effect. Meditating here will balance all your emotions (good, bad, right, wrong), and help you clearly perceive yourself.
Top of the Head (Crown Chakra): Closed eyes focused upwards, as if looking through the very top, center of the head. This area is the Crown Chakra, the Tenth Gate. This stimulates the pineal gland and the Crown Chakra, creates a sense of expansiveness, and cultivates God Consciousness.
1/10th Open (9/10th Closed): Eyelids are light and relaxed, open 1/10th, just enough to see out of them. This eye focus slightly stabilizes the optic nerve, minimizes sensory input which helps in meditation, and calms and develops intuition.