Why do people make odd facial expressions when self-administering eye drops?

— Akarsh

A: People often make oddly tense facial expressions when putting eye drops in their own eyes because the activity significantly tasks the nervous system.

To place a drop in your eye, you need to control yourself while something approaches a sensitive part of your face. People instinctively tense their facial muscles and may open their mouths as part of this effort. This is similar to the involuntary grimaces people make when doing something requiring fine motor control, like threading a needle.

The brain doesn’t always activate only those muscles needed for an activity. When you focus on a difficult movement, especially one involving your hands, other muscles can also become activated unnecessarily. Facial muscles are particularly prone to this.

Next, the eye blinks reflexively when the dropper approaches it, so you need to deliberately suppress blinking while also keeping your eye open and aiming accurately, creating tension around the eyes, forehead, and the mouth. Some people unconsciously open their mouths as part of the attempt to hold still.

People sometimes also hold their breath when concentrating, including if they have previously found eye drops uncomfortable, and opening the mouth can ease breathing.