Why does one eye feel drier than the other?

One eye often feels drier than the other because of something on that side of you: the pillow you sleep on, a fan, a heating vent, the car window, or a monitor set off to one side. Those cut blinking or speed evaporation on one eye more than the other. If you can’t find a cause, or the difference comes with pain, discharge or vision changes, see an eye doctor.

Can one eye be drier than the other?

Yes. Your two eyes share a lot, but they don’t live in exactly the same air. Each one has its own tear film, its own eyelids and its own exposure to the room. Small differences in airflow, light or how fully each lid closes add up over a day, and it’s common for one side to feel worse. Noticing it is useful: an uneven pattern often points to a cause you can change.

Sleeping on one side

If you always sleep on the same side, the eye against the pillow and the eye facing the room have different nights. Some people’s lids don’t close completely during sleep, and the upper eye is the one exposed to a fan or a heating vent. The lower eye, pressed into fabric, can pick up lint or feel scratchy from pressure. Notice which eye feels worse first thing in the morning and compare it with the side you sleep on.

• Turn ceiling fans down or off at night, or move the bed out of the airflow.
• Point a bedroom heater or humidifier so it isn’t blowing across your face.
• Change and wash pillowcases often.
• If someone tells you your eyes don’t fully close while you sleep, mention it to an eye doctor.

Waking up with dry eyes in winter covers the bedroom in more detail.

A vent, fan or window on one side

Look around the places you spend the most time. One-sided airflow is the most common everyday reason for one drier eye:

• At work, a ceiling diffuser or a desk fan to your left or right.
• At home, the couch next to a floor register, a window unit or a space heater.
• In the car, the driver’s window cracked open, or the dashboard vent nearest you aimed at your face.
• For drivers who rest an elbow on the open window, the eye on that side gets the most wind.
• On a train or plane, the overhead air nozzle set slightly to one side.

Try swapping sides for a week: sit on the other end of the couch, close the window on the highway, turn the vent away. If the dry eye switches sides or settles, you’ve found your answer.

A screen off to one side

With two monitors, many people put their main screen slightly off center, or work on a laptop set to one side of a big monitor. Turning your head or eyes to one side for hours changes how wide each eye opens; the eye that’s more open loses more moisture between blinks. The same goes for watching TV from an angle every evening. Center your main screen, keep its top at or a little below eye level, and take regular breaks. Screens and your tear film explains why screens matter.

Other everyday reasons

• Glasses with a scratched or smudged lens on one side, which can make you squint that eye.
• Sun from the same side every day, such as a desk by a window or a regular drive with the low sun on your left.
• Makeup applied more heavily on one side, or eyeliner close to the lash line of one eye.
• Rubbing one eye out of habit.
• Holding a phone to one side or reading in bed lying on one side.
• A contact lens in one eye that’s old, damaged or different from the other. The Quell label doesn’t cover contacts, so ask your eye doctor.

Using eye drops when one eye is drier

Quell’s directions are Apply 1 drop 3 times per day in each eye, so the label calls for both eyes, not just the one that feels worse. If you’re tempted to use extra drops in the drier eye, that’s a sign to look harder for a one-sided cause, or to ask an eye doctor about it. Quell is designed to reinforce the tear film’s oil layer to help reduce moisture loss, but it can’t fix a vent pointed at your face.

If you use a different drop in one eye on a doctor’s advice, ask that doctor or your pharmacist how Quell fits in, because the label doesn’t cover using it with other eye drops.

When one dry eye needs an eye doctor

A difference that comes and goes with your surroundings is usually an everyday thing. A difference that’s new, persistent or getting worse should be looked at, especially with any of these:

• Pain, or a feeling that something is stuck in the eye that won’t go away.
• Blurred vision, sensitivity to light, or any change in how you see from that eye.
• Discharge, crusting, or swelling of the eyelid on one side.
• The eye looks different from the other, or the eyelid sits differently.
• Symptoms that started after an injury, a splash, or something getting in the eye.

An optometrist or ophthalmologist can examine both eyes and work out what’s going on. The label is plain about when to stop: 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. Our list of eye symptoms that need a doctor has more, and the dry eye self-check can help you organize what you’ve noticed before an appointment.