By Dr. Mark Page · · 4 min read
A patient who moved from Seattle told me her eyes had started burning by mid-afternoon within about eight months of arriving, and she was convinced something had gone wrong. Nothing had. She had moved from roughly seventy percent humidity to something that regularly drops below ten.
This is one of the most common presentations in our practice, and the Phoenix-specific version of dry eye is worth understanding properly, because the standard advice does not work here as well as it does elsewhere.
How the tear film actually works
Your tears are not just water. They have three layers, and the one that matters most in this climate is the outermost.
Against the eye is a mucin layer that helps tears spread. Above it is the watery layer that most people think of as tears. On top of that is a thin oil layer, produced by glands in your eyelid margins, whose entire job is to stop the water underneath evaporating.
When that oil layer is thin or absent, your tears evaporate before the next blink replaces them. You can be producing plenty of tears and still have a dry ocular surface, which is why volume is the wrong thing to measure.
The four Phoenix factors
- Humidity
- Relative humidity here regularly drops into single digits. Evaporation from any wet surface, including your eye, accelerates as the surrounding air gets drier. This is simple physics and it operates all day.
- Air conditioning
- We run it for most of the year, and it moves dry air across the eye surface continuously. Vents aimed at the face, in cars and offices, are one of the most common aggravating factors we find and one of the easiest to fix.
- Dust
- Monsoon season haboobs and everyday desert particulate deposit material on the ocular surface, which triggers inflammation. Inflammation makes the meibomian glands work worse, which makes evaporation worse, which is a genuine feedback loop.
- Ultraviolet
- Phoenix leads the country in UV index for much of the year. UV contributes to ocular surface inflammation independently of humidity, and over decades it contributes to pterygium, which itself disrupts the tear film.
Why your dry eyes water
This confuses more patients than anything else. Constant watering is one of the most common presentations of dry eye, not evidence against it.
The mechanism is straightforward once explained. A dry, irritated ocular surface triggers a reflex response, and the lacrimal gland floods the eye with watery tears. Those reflex tears have no oil layer to speak of, so they do not stay on the eye. They spill over and run down your face without relieving anything.
So the patient who says my eyes water constantly, they cannot be dry is often describing textbook dry eye.
Why over-the-counter drops disappoint
Most people arrive having tried three or four drops from a pharmacy shelf with brief relief at best, and having concluded that nothing works.
The usual explanation is that the drops were treating the wrong layer. If your problem is a failing oil layer, adding more water gives you a few minutes of comfort and then evaporates on the same schedule as your own tears. You are topping up the thing that was never the problem.
Evaporative dry eye needs treatment aimed at the meibomian glands: sustained heat at sufficient temperature to liquefy blocked contents, physical clearing, and where inflammation is driving it, prescription anti-inflammatory therapy.
What actually helps here
- Redirect every air vent away from your face. Car, office, bedroom ceiling fan. This one change resolves a surprising number of cases and costs nothing.
- Warm compresses done properly, which means sustained heat for long enough to liquefy the gland oil. Most home attempts use a flannel that cools within a minute and achieve nothing.
- A humidifier in the bedroom, since eight hours of overnight exposure to single-digit humidity does real damage before your day starts.
- Deliberate full blinking at screens. Partial blinks do not resurface the tear film and are extremely common during concentrated work.
- Wraparound sunglasses outdoors, which cut both UV and the wind-driven evaporation that a standard frame does not block.
- Omega-3 supplementation, which has reasonable evidence for improving the quality of meibomian secretions.
- Getting the type diagnosed, because evaporative and aqueous deficient dry eye need genuinely different treatment.
When to stop adapting and get it looked at
The reason to treat dry eye is not only comfort, though comfort matters. Chronic untreated dryness causes inflammation and damage to the corneal surface, and untreated meibomian gland dysfunction can cause permanent loss of gland structure. That loss is not recoverable.
So if you have been managing with drops for more than a few weeks, if your vision fluctuates and clears when you blink, or if your contact lenses have quietly become uncomfortable, that is worth an appointment rather than another brand of drops.
Want the full detail?
Read about dry eye treatmentThis article is general educational information, not medical advice or a diagnosis, and it is not a substitute for an examination. If you are experiencing sudden vision loss, eye pain or an eye injury, contact us immediately or go to an emergency room.