How blinking spreads tears across the eye

A blink works like a windshield wiper with a built-in washer. As the upper lid closes, it pushes old tears toward the inner corner to drain, and as it opens, it lays down a fresh, even film of water, mucus and oil across the eye. Complete blinks renew the whole surface; partial blinks, common when you concentrate or look at screens, leave the lower part to dry.

A blink, step by step

• The upper lid starts to fall. The lower lid barely moves; most of the work is done from above.
• As the lids close, the upper lid’s edge sweeps across the eye, moving the old tear film and any dust with it.
• When the lids meet, gentle pressure squeezes a little oil from the glands along their edges.
• The used tears move toward small openings near the inner corner of each eye, where they drain toward the nose.
• As the upper lid lifts, it draws a new layer of tears up over the eye, with oil spreading over the top.
• For a moment the film is even and complete, then it starts to thin until the next blink.

All of that happens in a fraction of a second, mostly without your noticing. You blink without thinking about it, although you can also choose to blink, which matters for the habits further down.

Why blinking matters for the oil layer

The tear film’s outermost layer is a thin coat of oil that slows evaporation. That oil comes from tiny glands in the lids, and the blink itself is part of how it gets out of those glands and onto the film. A full, firm closure helps express it; a flutter that doesn’t bring the lids together helps less. So blinking does two jobs at once: it replaces water and it refreshes the oil that keeps that water from evaporating. The tear film’s oil layer covers what that oil does once it’s there.

Partial blinks while concentrating

When you focus hard on something, reading, threading a needle, driving in traffic, the brain tends to hold off on blinking so you don’t miss anything. Many of the blinks that do happen are incomplete: the upper lid comes partway down and goes back up without meeting the lower lid. That leaves a strip along the bottom of the eye that doesn’t get a fresh film. People who notice dryness or a burning feeling mainly along the lower edge of the eye after reading are often noticing that strip.

Why screens reduce blinking

Screens combine several things that work against a healthy blink. You concentrate, which reduces blinking. You often look straight ahead or slightly up at a monitor, so the eye opening is wider and more surface is exposed. Rooms with computers tend to have heating or air conditioning blowing, which speeds evaporation from a film that’s already being renewed less often. Screens and your tear film covers the setup side of this.

Blink breaks: a simple routine

You can’t stop concentrating, but you can build complete blinks into your day on purpose:

• Set a reminder on your phone or computer to go off at regular intervals during long screen sessions.
• When it goes off, look away from the screen at something across the room or out a window.
• Close your eyes gently and fully, hold for a second or two, then open. Repeat a few times.
• Check that your lids actually meet; a light squeeze at the end confirms it.
• Go back to work and let your blinking return to normal.

Lowering your monitor so you look slightly down also helps, because the lids then cover more of the eye even between blinks. Keeping fans and vents from blowing at your face gives each fresh film longer before it thins.

When blinking feels different

Blinking more than usual, a feeling that you have to blink hard to clear your vision, or twitching lids are things people often notice when their eyes are dry or tired. They can also have other causes. If changes in blinking come with pain, vision changes or don’t ease, an eye doctor should take a look. The label’s guidance on that is: Stop use and ask a doctor if you feel eye pain or changes in your vision, if irritation or redness continues, or if the condition worsens or persists for 72 hours.

Where drops fit in

A lubricating drop adds to the tear film from the outside, and blinking is what spreads it. After putting a drop in, close your eyes gently and blink a few times so it covers the eye evenly, rather than squeezing hard, which can push it out. Quell’s directions are Apply 1 drop 3 times per day in each eye, and its Uses are For use as a protectant against further irritation or to relieve dryness of the eye. It’s designed to reinforce the tear film’s oil layer to help reduce moisture loss, which works alongside the oil your own blinks deliver. See how to use eye drops as directed for the full routine, and keep the tip clean: Do not touch tip of bottle to any surface to avoid contamination.