If your eyes feel dry, gritty or stinging by the end of the day, the first option is over-the-counter artificial tears. What makes the difference isn’t so much the brand as the format — single-dose vials or a bottle — and consistency: they are applied on a schedule through the day, not as a rescue once the discomfort has set in. If you’re no better after a few days, the next step isn’t trying a fifth brand, it’s having someone look at the eye.
What’s actually going wrong when an eye dries out
Dry eye doesn’t always mean “not enough tears”. According to the National Eye Institute, it can come from three different things: the glands not producing enough tear fluid, the tear film evaporating too quickly, or the tears you do produce not doing their job properly. Which is why two people with the same symptom can need different products.
Typical symptoms are a gritty feeling, as though something were in the eye, stinging or burning, red eyes, discomfort in bright light, and intermittent blurred vision that clears when you blink.
Some people are likelier to get it: being 50 or over, being a woman, wearing contact lenses, not getting enough vitamin A or omega-3, and having certain autoimmune conditions such as lupus or Sjögren’s syndrome. Long hours in front of a screen are also associated with dry eye, essentially because you blink far less than you think.
The formats, and who each one suits
The artificial tears sold in pharmacies share one aim — to lubricate and stabilise the tear film — and differ mainly in packaging and viscosity.
| Format | When it fits | What to bear in mind |
|---|---|---|
| Preservative-free single-dose vials | Frequent or long-term use, sensitive eyes, contact lens wearers | Each vial is used once and discarded even if fluid is left |
| Multi-dose bottle with preservative | Occasional or one-off use | Respect the in-use period after first opening, which is shorter than the printed expiry |
| Eye gel | Persistent discomfort that drops don’t settle | More viscous: can blur vision for a few minutes |
| Night-time lubricating ointment | Dryness on waking, eyes that don’t fully close in sleep | Blurs vision, which is why it’s kept for bedtime |
On active ingredients, two of the most common in Spain are authorised as medicines and you can read their full leaflet on CIMA, the AEMPS database: hypromellose (a cellulose derivative that increases viscosity and adheres well to the cornea and conjunctiva) and carmellose sodium, whose formulations include salts designed to resemble the natural composition of tears. If you want to know whether a specific eye drop is authorised as a medicine in Spain, search for it by name on CIMA.
The usual regimen given in the hypromellose product information is one drop in the affected eye 3 to 5 times a day, or more often if needed. And there is a sentence in those leaflets worth holding on to: treating dry eye requires an individualised dosing regimen. In other words, the starting schedule is a guide, and it gets adjusted.
How to put a drop in properly
It sounds trivial and isn’t: a good share of “it does nothing for me” complaints start here.
- Wash your hands before touching the container.
- Check the single-dose vial is intact. It opens by levering the winged tab, not by twisting.
- Pull the lower lid gently down to form a pocket and look up.
- Squeeze the container to release one single drop into that pocket. The eye can’t take more: a second drop just overflows.
- Blink a couple of times, normally. Don’t squeeze your eyelids shut.
- Don’t let the dropper touch the eye, the lashes or any surface. That’s the commonest route to contamination, and the leaflets warn that dropper contact with the eye can damage the surface of the eye.
- If you use several different eye drops, leave at least 5 minutes between them. Otherwise the second washes out the first.
Two storage details people often skip. A single-dose vial is thrown away after use even if solution is left: it isn’t kept for the next dose. And a multi-dose bottle has an in-use period from first opening that is independent of the printed expiry date — for bottled hypromellose, for example, it is 6 weeks — so write the opening date on the box. Nor should you use an eye drop if the solution has changed colour or gone cloudy.
If you wear contact lenses
Here the format stops being a preference and becomes a specific instruction, and it depends on whether the product contains a preservative:
- Preservative-free (single-dose): you don’t need to remove soft lenses to apply it.
- With preservative (bottle): take soft lenses out before applying and wait at least 15 minutes before putting them back in.
Always check this part on the leaflet of the product you actually bought, because it varies between formulations.
Side effects, and one little-known warning
These are very safe products, but not inert. With hypromellose, burning, blurred vision and sticky eyelids are described as uncommon (between 1 and 10 in every 1,000 patients). With carmellose sodium, eye irritation, pain, itching and visual disturbance are listed as common (up to 1 in 10 people).
Watch out for the blurred vision: carmellose can cause it transiently, usually for 1 to 15 minutes. If you’ve just applied it, don’t drive or operate machinery until you can see sharply.
And a warning almost nobody knows about: many of these eye drops contain phosphates as an excipient. If you have severe damage to the cornea, treatment with phosphates can, in very rare cases, cause calcium deposits that cloud the cornea. One more reason to have a damaged eye assessed by a professional rather than treating it yourself.
What you can change without buying anything
The environmental measures the National Eye Institute recommends add up to more than you’d think:
- Avoid smoke, direct wind and the blast from air conditioning or a car heater.
- Use a humidifier if the air at home is very dry.
- Limit screen time and take breaks: blink deliberately when you’ve been at it a while.
- Wraparound sunglasses outdoors.
- Drink enough water and sleep 7 to 8 hours.
If dry eye starts or worsens after beginning a new medicine, mention it: sometimes that is the cause and it can be reconsidered.
When to see a doctor
Stop self-treating and get a professional assessment if any of these appear:
- Eye pain — not discomfort, pain — or pain that doesn’t let up.
- Loss or worsening of vision, or blurred vision lasting beyond a few minutes after applying the drop.
- Intense redness, discharge, crusting, flaking, or a sore on the eye or eyelid.
- A history of a blow, injury or foreign body in the eye.
- A dry mouth alongside joint pain or stiffness, which can point to an autoimmune condition.
- No improvement after a few days of correct use. The leaflets are explicit: see a doctor if you get worse, or if you are no better after 3 days with single-dose presentations and 7 days with the bottle.
Severe untreated dry eye can end up damaging the cornea, and there are treatments available only on prescription or in clinic — from immunomodulating drops to punctal plugs — for cases artificial tears don’t resolve. Persisting with over-the-counter drops when something is wrong only delays that step.
This information is general guidance and does not replace assessment by a healthcare professional. Always read the leaflet of the specific product you use. Sources: Patient leaflet, Hypromellose 3.2 mg/ml single-dose eye drops (CIMA, AEMPS, in Spanish), Patient leaflet, Artific 3.20 mg/ml eye drops solution (CIMA, AEMPS, in Spanish), Patient leaflet, Carmellose 5 mg/ml single-dose eye drops (CIMA, AEMPS, in Spanish) and Dry Eye, National Eye Institute (NIH).