Dry Eye
Management of insufficient or unstable tears causing burning, irritation or fluctuating vision
What is dry eye?
The surface of the eye is covered by a tear film in three layers. An oily layer made by glands in the lid margins stops the tears evaporating, a watery layer underneath carries oxygen and antibodies, and a sticky layer holds the whole film against the surface. Dry eye is a fault in that film, and in most people the fault is the oil.
When the lid glands block or their oil thickens, the film breaks up within a few seconds of each blink and the surface is left exposed between blinks. The exposed surface becomes inflamed, and the inflammation damages the glands further, so it tends to keep itself going once it starts.
The common drivers are ordinary. Concentrating on a screen cuts the blink rate by more than half. Air conditioning, fans, dust and smoke strip the film faster. Contact lens wear, the hormonal changes around the menopause, several long-term medicines including some for blood pressure, allergy and depression, and a group of autoimmune conditions all contribute. The surface of your eye is often watering at the same time, because a dry, irritated surface triggers a reflex flood of tears that runs down the cheek without ever coating the eye properly.
What you might notice
- Eyes that feel gritty or burning
- An eye that waters constantly
- Blurry or dim vision
How it is diagnosed
Your eye doctor examines the lid margins at the slit lamp, pressing gently on them to see whether the oil that comes out is clear or thickened and whether the gland openings are blocked or scarred. That single observation decides most of what happens next.
They then put a drop of orange dye on the surface, ask you to blink once and count the seconds until the film breaks up. A film that breaks in under ten seconds is unstable. Under the blue light the same dye stains any patch of surface where cells have been damaged by drying, and where those patches sit tells them which part of the film is failing.
A small paper strip tucked into the lower lid for five minutes measures how much watery tear you actually produce. Alongside this they check for allergy, for inflammation of the lid margins and for the joint, mouth and skin symptoms that point to an autoimmune cause, because dry eye that is part of something larger is treated differently from dry eye that is not.
Recovery
Lubricating drops work within minutes and wear off within hours, so they relieve the symptom without changing the cause. Use them as often as you need to, and choose a preservative-free form if you are using them more than four times a day.
The treatments that change the cause are slow. Warm compresses and lid cleaning, done properly for ten minutes daily, take six to eight weeks to show a difference and stop working when you stop doing them. Anti-inflammatory drops are judged at three months. Omega-3 supplements and changes to your screen habits work on the same timescale.
Set your expectations for control and not for cure. Most people reach a point where they are comfortable through a normal day and need to do more during a dusty season, a long flight or a heavy stretch at the computer. Your doctor will review you at six to eight weeks to see whether the surface staining has improved, since that improves before the symptoms do.
If it is left untreated
Dry eye that is left alone rarely threatens sight, and for most people the cost is measured in comfort, concentration and the number of hours they can work or read before their eyes give up. That cost is substantial and is a good enough reason to treat it.
The surface damage does accumulate. Persistent drying leaves the cornea irregular, so vision fluctuates through the day and blurs between blinks. Severe or long-standing disease can thin the surface, scar it and, uncommonly, allow an infection to take hold in a surface that has lost its defences. Contact lenses become progressively harder to tolerate, and an unstable film makes laser vision correction a poor idea until it has been settled.
The lid glands themselves are the part that does not come back. Glands that stay blocked long enough drop out permanently, and the oil layer they were making cannot be replaced by drops. Treating early keeps glands that treating late cannot recover. A red, painful eye with light sensitivity and falling vision is a different problem and needs seeing the same day.
Questions about dry eye
My eyes water constantly. How can they be dry?
Watering is one of the commonest ways dry eye presents. The tear film has an oily layer that stops it evaporating, and when that layer fails the surface is left exposed between blinks. The exposed surface is irritated, and irritation triggers a reflex flood of watery tears from the main gland. That flood is the wrong kind of tear, it arrives too fast to spread properly, and it runs down your cheek without ever coating the eye. Treating the oil layer, with warm compresses and lid cleaning, usually reduces the watering. Watering with a sticky discharge or a swelling near the inner corner is a blocked drainage duct instead, which is a different problem.
Will I become dependent on lubricating drops?
No. Lubricating drops sit on the surface of the eye and are not absorbed into the gland that makes your tears, so using them does not reduce your own tear production or create a dependence. If you find you need them more often over time, that reflects the underlying condition progressing and is worth a review, not the drops themselves. One thing does matter: preservatives. If you use drops more than four times a day, use a preservative-free form, because the preservative in a multi-dose bottle is itself irritating to an already inflamed surface at that frequency.
How long before it gets better?
Lubricating drops relieve the symptom within minutes and wear off within hours. The treatments that address the cause are much slower. Warm compresses and lid cleaning done properly for ten minutes daily take six to eight weeks to show a real difference, and anti-inflammatory drops are judged at three months. Most people are stopping too early and not being given the wrong treatment. Your doctor will review the surface staining at six to eight weeks, and that usually improves before the symptoms do. Expect to reach good control and to need extra drops during a dusty season, a long flight or heavy screen work.
Other ophthalmology treatments
Removal of a cloudy natural lens and replacement with an artificial lens to improve vision
Day CareLaser vision correction that reshapes the cornea to reduce dependence on glasses or contact lenses
Day CareTalk to a care coordinator about dry eye
Leave a number and a care coordinator calls you back with what the treatment involves and which hospital it would be at. They book a consult only if you want one