Look at Tommy's eyebrows, and feel above your own eye. Like you, Tommy has a big top eyelid with long eyelashes, and a small bottom eyelid with shorter eyelashes. His lids open and close from top to bottom, but not from side to side. The outside two are the ones we usually see. On eagles the bottom eyelid is bigger than the top eyelid, so they blink up instead of down.
Birds also have an inner eyelid, called a nictitating membrane.
This eyelid is transparent, and sweeps across the eye from side to side. It grows in the inner corner of the eye, right next to the tear duct. Look in your partner's eye or in a mirror and see if you can see a tiny hole in both the upper and the lower eyelids, right in the inner corner of your eye. These are tear ducts. Tears help to keep the eye moist, and have a special chemical called a lysozyme that kills bacteria, protecting the eyes from infection.