Owls have 2 sets of eyelids. One is the nictitating membrane and the other is its regular eyelid. The nictitating membrane is a translucent eyelid that are used to protect and keep the eye moist while the owl maintains its vision. It is a very handy thing to have.
While owlets primarily depend on sound for hunting, vision is also very important to them. They have keen sight and use it in social behaviors. Owlets will try very hard to make eye contact while tweeting and chattering when begging for food or wanting attention. They are very curious creatures and like to use their eyes in order to keep from being ignored.
Owls eyes are fixed in their sockets and they can only get depth perception by moving their head from side to side. Therefore, if they were trying to get your attention and you were a familiar person to them, they would move their heads in all kinds of positions and hop around you while tweeting in an attempt to make eye contact with. Lol.