Dry eyes

The surface of the eye is covered at all times by a very thin film of water, oil and mucus. While the film holds together you never notice it; the moment it breaks up between blinks, the eye starts complaining — it burns, it scrapes, as though sand had been tipped under the lid. The complaint is usually put down to screen fatigue, and in most cases that is exactly what it is. But the same dryness has quite different things behind it: half the causes lie not in the eye but in the medicine cupboard or in a whole-body illness, and they only come to light if you know what to look for.

The eyes stream and the diagnosis is dryness

This is the first thing that throws people. Somebody comes in complaining that their eyes water: they sting in the wind, they run in cold weather, they have to be dabbed with a tissue. On hearing the word «dryness» the person does not believe it — how can something wet be dry?

Here is how it works. The tear gland produces two separate flows. One is steady and sparing, and it is the one that maintains the film. The other is the emergency flow: irritation triggers it and it releases a burst of very watery tear. When the steady flow falls short, the surface becomes irritated and the brain presses the emergency button again and again. Tears pour out, but this is water without the oily part: it runs down the cheek and spreads poorly across the eye. The surface stays dry.

Hence a practical consequence: watering in the wind, in the cold and towards the end of the day is a classic sign of dry eye, not an argument against it. And drops that «dry things up» do precisely the opposite of what is needed here.

The film breaks down in two different ways

The distinction matters, because each one responds to something different.

• There is too little tear. The gland makes less fluid than it should — this happens with age, after the menopause, in whole-body illnesses and after radiotherapy to the head.
• The tear evaporates too quickly. There is enough fluid, but the oily layer that stops it drying out is faulty. The oil comes from glands inside the eyelid, and their openings block easily: the lid margins turn red, there are crusts on the lashes in the morning, and everything is worse by evening. This is the commoner pattern, and it is the one treated with warm compresses rather than with drops.

Most people have both at once, simply in different proportions.

What dries the eyes out day after day

• The screen. While working at one, people blink three to four times less often than usual, and blink incompletely at that, so the film never gets rebuilt. What helps is not «resting your eyes» in the abstract but deliberate full blinks and a break every twenty to thirty minutes.
• Age: beyond fifty dryness is very common, and it starts earlier and more often in women.
• Contact lenses, particularly when worn for longer than intended and without days off.
• Dry air: air conditioning, heating, a car vent aimed at the face, aircraft cabins, wind and dust.
• Smoking and smoky rooms, other people's smoke included.
• Eye operations, laser vision correction among them: dryness afterwards is normal and usually settles over a few months.
• Lash extensions, permanent eyelid make-up and eyeliner along the inner lid margin, which is exactly where the oil glands open.

Medicines nobody thinks of

This is the most frequently missed cause and at the same time the one you can actually do something about. Dry eyes are caused by:

• antihistamines taken for allergy;
• antidepressants, especially the older groups, and also sleeping and anxiety medicines;
• diuretics and some blood pressure medicines, beta blockers included;
• isotretinoin, prescribed for severe acne;
• medicines for an overactive bladder, for travel sickness and for spasm;
• hormonal contraceptives and menopausal hormone therapy;
• glaucoma drops, both through the active ingredient itself and through the preservative when they are used for years.

Never stop a prescribed medicine on your own initiative. The right move is to go to your doctor with a list of everything you take, over-the-counter items included. Sometimes it is enough to switch to another drug within the same group, or to a preservative-free form, and the eyes settle within a fortnight.

When dryness is not about the eye but about the whole body

There are illnesses in which the immune system attacks the glands that make fluid. The chief one is Sjögren's syndrome. It is not recognised by the eyes on their own but by the combination:

• dry eyes lasting months and not yielding to the usual measures;
• a dry mouth: dry bread is hard to swallow without a drink, you wake in the night for water, teeth decay quickly;
• joint pain and morning stiffness, marked fatigue;
• sometimes dry skin and mucous membranes, and swelling of the salivary glands in front of the ears.

This is a systemic disease and not «screen fatigue», and it belongs with a rheumatologist: blood tests and an assessment of the salivary glands are needed. If your eyes and your mouth are drying up at the same time, say so explicitly — taken separately, the two complaints go to different specialists and never meet in the same set of notes. The other half of that pair is set out on the neighbouring page, «Dry mouth».

Dry eyes also occur in rheumatoid arthritis, in lupus, in thyroid disease (where the eyes additionally protrude and the lids no longer close fully), in diabetes, after a bone marrow transplant, and in some injuries to the facial nerve where the lid stops shutting.

What genuinely helps

• Artificial tears. They are used not «when you can no longer bear it» but to a timetable, several times a day, over weeks. If you need them more than four to six times daily, choose a preservative-free form: instilled often, the preservative irritates the surface in its own right. Gels and ointments are thicker and last longer but blur the vision for a while, which makes them convenient at night.
• A warm compress on the closed lids for five to ten minutes, followed by gentle massage of the lid margin with a finger, from top to bottom, and cleaning with a mild product. Daily and for at least a month — the effect does not show up sooner. This is the mainstay of treatment when the lid glands are blocked.
• Rearranging the workstation: the screen below eye level so that the lids cover more of the opening, the airflow not pointed at the face, and a humidifier in the room.
• A break from lenses: glasses rather than lenses on bad days.
• Giving up smoking, and moving away from other people's smoke.
• If the lid stays slightly open during sleep, your doctor may advise ointment at night and taping the lid shut — that heals things faster than anything else on this list.

When these measures are not enough, an ophthalmologist adds treatments that are not sold over the counter, up to plugging the tear ducts with tiny stoppers so that your own tear stays on the eye for longer.

What not to do

• Using vasoconstrictor drops «to take the redness out». They clear the red within minutes by narrowing the vessels, but they moisten nothing at all. With repeated use the vessels respond by widening further still, the eye ends up redder than before, and the person reaches for the bottle more often. In a dry eye that is a spiral with only one direction.
• Using antibiotic or steroid drops left over from a previous occasion. Steroid drops without supervision raise the pressure inside the eye and hold back healing.
• Rubbing the eyes. It relieves things for a second and damages the surface; constant rubbing can change the shape of the cornea.
• Bathing the eyes in tea, camomile or home-mixed salt water: the residue from the brew and the wrong concentration irritate more than they soothe.
• Wearing lenses when the eye is painful, red or the vision has blurred. The lens comes out and does not go back in until the eye has been examined.

This is no longer dryness: when to be seen urgently

Dryness is unpleasant but it does not take away sight. Everything listed below is a sign of something else, and it needs sorting out the same day; the first few points immediately, by calling an ambulance or going to an eye casualty department:

• pain inside the eye rather than soreness on the surface, all the more so if it is severe and comes with nausea;
• it hurts to look at light, the eye screws up and waters in brightness;
• the sight has worsened: a veil, flashes, floating specks, crooked lines or a missing patch of the visual field;
• the redness is deep and dark, forming a ring around the iris rather than spread across the white;
• coloured haloes around lights, a hard eye, a headache on the same side and nausea — that is how a sudden rise in eye pressure shows itself;
• injury to the eye, or a metal fragment, glass, lime or any chemical getting into it;
• pus, swollen lids and a temperature;
• any pain or redness in a contact lens wearer: take the lens out at once and be seen the same day, because in lens wearers an infection of the cornea sets in within hours.

Not urgent but not to be left, a visit to the ophthalmologist is due if the dryness does not yield to home measures within a few weeks, if the shape or position of the lids has changed, or if dry eyes appear in a child or a teenager.

Online consultation

More than half the questions on this subject can be settled remotely. The doctor will work out which kind of dryness you have — too little tear, or tear that evaporates too fast — and that determines what will help you: the drops or the daily lid routine. They will go through your list of medicines separately and point out what is worth raising with whoever prescribed them. They will ask about a dry mouth, about your joints and about fatigue so that a whole-body cause is not missed, and explain which tests make sense. Above all, they will separate ordinary dryness from the signs that call for the eye to be examined the same day.

This material is for information only and does not replace medical advice.