HealthInfo Canterbury
Symptoms and causes of dry eyes
Your tears, which keep your eyes moist, are a mixture of three layers – oils (lipid layer), water (aqueous layer) and mucus.
The oils are on the outside and are made by the meibomian glands in your eyelid. These oils help to stop the watery layer underneath from evaporating too quickly.
The tear ducts (lacrimal gland) in your upper eyelids make the middle water layer. This keeps your eyes moist and washes out dust or anything else that gets in your eyes.
The cells on the surface of your eyes (conjunctiva) make a mucus, which helps the watery layer to stick and spread over your eyes.
What are the symptoms of dry eyes?
Common symptoms include:
- eyes feeling gritty or sandy
- red eyes
- sore eyes, often with a burning feeling
- variable or blurred vision that gets better after blinking
- uncomfortable contact lenses
- being very sensitive to light.
What causes dry eyes?
Many different things can contribute to having dry eyes.
Age and gender
As we get older we make fewer tears. Women are also more likely to get dry eyes because of the hormonal changes that happen with their periods, pregnancy, breastfeeding, and menopause.
Reading
Using your eyes for fine tasks such as reading for a long time can contribute. We blink less when we're reading a computer screen, when reading print, or when we're watching TV.
Environment
Dry or windy climates, higher temperatures, pollution, and smoking can all make your eyes dry.
Other eye conditions
These include blepharitis, ectropion (when your eyelid turns out, which can happen as you get older), a problem with your meibomian glands, refractive surgery (especially LASIK), pterygium or pinguecula, an eye injury, or abnormal blinking. As well, wearing contact lenses increases your risk of getting dry eyes.
Other diseases
These include autoimmune and connective tissue diseases such as Stevens-Johnson and Sjögren's syndrome, hepatitis C, HIV and Aids, sarcoidosis, diabetes, hormone deficiency, and rosacea.
What you eat
If you don't eat enough omega-3 fatty acids and too many omega-6 fatty acids you can get dry eyes.
Medicines
Certain medications such as chemotherapy, diuretics, antidepressants, antihistamines, hormone replacement therapy, beta blockers, and oral isotretinoin for acne can cause dry eyes.
HealthInfo recommends the following pages
- EyeSmart – What is dry eye?
Several web pages explaining what causes dry eyes, its symptoms, who is at risk, diagnosis and treatment.
On the next page: How are dry eyes diagnosed?
Written by Canterbury optometrists. Adapted by HealthInfo clinical advisers. Endorsed by clinical director, Ophthalmology, Canterbury DHB. June 2016.
SourcesReview key: HIDRE-206293
