The normal tear fluid that lubricates the eyes is made up of three layers – an oily (lipid) layer, a watery (aqueous) layer, and a sticky (mucous) layer – and these normal tears are what prevent our eyes from feeling dry.
You release extra tears when you cry. These are the same tears that are also triggered when something goes into or irritates the eye including chopping onions.
What is dry eye?
People with dry eye either don't make enough normal (lubricating) tears or the ones that they make are of poor quality, causing the tears to dry up too quickly and the front of the eye to become dry and irritated. As a result, dry eye can be uncomfortable and cause the eye to produce the watery type of tears. This only helps for a short time – leaving the eye uncomfortable and gritty.
If your eyelids are sore and red, you may also have another condition called blepharitis. Blepharitis is a condition that affects the eyelids making them sore and inflamed. If the eyelid glands become blocked, you may have a condition called meibomian gland dysfunction. It is quite common to have a combination of these conditions.
Dry eye doesn't tend to cause serious damage to the eyes, but it can be very uncomfortable. Severe cases do have a risk of causing long-term damage, but fortunately these are rare.
Dry eye is much more common in people over the age of 50. This is often because the glands that make the normal tears, and particularly the oily part of the tears, tend to become less effective as you get older. Also the tears tend to spread across the eye less well with age.
Some general health conditions can cause dry eye as a side effect, such as autoimmune diseases and hormonal changes. The condition is also more common in windy, cold, dry and dusty conditions.
If you’re concentrating on your computer or smartphone for long periods of time without a break, this may also make your eyes feel dry.
Air conditioning and central heating can make dry eye worse too, as can some medications and general health problems.
Smoking has also been linked to dry eye as it may both cause the condition and make it worse.
People with dry eye may get some or all of the following symptoms.
- A sandy or gritty feeling
- Sore eyes
- Uncomfortable and sometimes painful eyes
- An itching or burning sensation
- Short-term blurred vision
- Watery eyes, as if you are crying (having watery eyes can mean you are producing poor-quality tears and actually have dry eyes)
Most cases of dry eye tend to be a long-term condition, meaning that you’ll need ongoing treatment.
There are lots of different types of drops and gels that can help your eyes feel more comfortable. The best ones don’t have preservatives in them, or if they do they contain very gentle preservatives, which helps to reduce irritation. They may also contain an ingredient called sodium hyaluronate, known to be very effective in treating the condition.
It’s important to use the correct type of drops. The wrong drops are unlikely to cause any harm, but they won’t help as much. If your drops aren’t working or you’re not sure which drops to use, your local optometrist can advise you and may be able to offer other treatment options.
Resources for your practice
You can download our patient leaflet on dry eye.
If you're a practitioner, we recommend that you use this information, following a suitable examination, to reinforce advice given to the patient who has symptoms of dry eye.
For more information on eye health and eye conditions, explore our For patients section.