Mineral oils are used in some special eye drops to help people whose tears dry up too fast. Normally, your tears have a little bit of oil in them to stop them from evaporating, like a lid on a pot to keep water from boiling away. When your eyes don’t make enough of this oil, they get dry and irritated. That’s where mineral oil eye drops come in—they add the oily layer back and help your natural tears stay longer. These drops are a bit thicker and feel different from watery ones, but they’re great for people who have meibomian gland problems (tiny oil glands in your eyelids). Some are even used at bedtime to keep your eyes moist while you sleep.