We rely heavily on the eyes of others. We believe they can tell us if the other person is alert, interested, cagey, lying, and a hundred other gut reactions we form about people before even opening our mouths or giving them a chance to speak for themselves. When we can't see a person's eyes we react to them differently. Sometimes it's a person we trust, like a priest or a superhero and it's a relief to us that we can't see them calculating our sins and misgivings. Other times it's a person we don't trust, like a bank robber or a dementor, and it's all the more frightening for us. In those instances we take other cues and form a decision about whether or not we can be okay with the fact that we can't see the eyes that see us. But even in entirely mundane instances, we take the lack of eyes as a vague threat. It makes us uneasy.
How would your character react to an entity whose eyes they can't see? Is that entity likely to be another person, or something else entirely?

Write. Comment. Repeat.
How would your character react to an entity whose eyes they can't see? Is that entity likely to be another person, or something else entirely?
Write. Comment. Repeat.