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A “red eye” is an eye that is red and bloodshot.

Bloodshot eyes are usually painless and usually develop when blood vessels near the surface of the eye become swollen. The tiny blood vessels (many of which normally are invisible) can become swollen because of environmental or lifestyle-related reasons or because of specific eye problems.

Red eyes are usually caused by an allergy, eye fatigue, over-wearing contact lenses or common eye infections such as conjunctivitis. However, redness of the eye sometimes can signal a more serious eye condition or disease, such as uveitis or glaucoma

Who can help you if you have red eyes?

You should see your optometrist if you have red, bloodshot eyes – especially if the redness started quickly, or you are uncomfortable, or have pain or blurred vision!

Many instances of red eyes are relatively harmless but, if your red eyes are accompanied by eye pain, light sensitivity, swelling, or blurry vision, you need to see your optometrist straight away.

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What causes a red eye?

Environmental causes of bloodshot eyes include;

  • Airborne allergens
  • Air pollution
  • Smoke, including second-hand cigarette smoke
  • Dry air, including from airconditioned offices, or a plane cabin
  • Dust
  • Chemical exposure, chlorine in swimming pools can cause irritation
  • Overexposure to sunlight


Allergies can affect the eyes, causing them to be red and swollen. Other symptoms that you may experience include:

  • itching
  • a burning sensation
  • increased tears

Eye allergy symptoms can also be accompanied by sneezing and an itchy, runny nose. Common allergy triggers include:

  • pollen
  • dust mites
  • mould
  • pet dander
  • irritants like cigarette smoke or air pollution

Dry Eye

Tears are made by small glands above the eyes that help protect and lubricate the eyes. You have dry eyes when your eyes don’t produce enough tears.

Dry eyes are very common, especially in women, people over the age of 50, and individuals who wear contact lenses.

If you have dry eyes, you may notice that your eyes appear red. Other symptoms include:

  • a stinging, scratchy, or burning sensation
  • feeling like something is in your eye
  • sensitivity to light
  • blurred vision (that comes and goes, especially when reading)


Many common medicines taken daily can cause bloodshot eyes. Antihistamines, sleeping pills, anti-anxiety pills, and some pain relievers like ibuprofen cause dryness and redness by reducing blood flow to the tissue in and around the eye.


Children are most likely to get conjunctivitis as they are in close contact with others in school or day care centres. Conjunctivitis can be very contagious, so it is important to see an optometrist or doctor for correct treatment of the infection.

Other symptoms that may occur with conjunctivitis are:

  • itching
  • a burning sensation
  • feeling like something is in your eye
  • increased tearing
  • discharge of mucus or pus, which can lead to crusting of the eyelids or eyelashes

Contact Lenses

In addition to eye redness, complications from contact lenses are:

  • eye pain
  • increased tearing
  • blurry vision
  • sensitivity to light

If you wear contact lenses and have any of the symptoms above, remove your contacts for a few hours. If your symptoms continue or become worse, contact your optometrist.

Digital Eye Strain

Eye irritation and discomfort from digital eye strain has become quite prevalent.

Symptoms can range from physical fatigue, dry eyes, eye twitching and red eyes. The discomfort is caused by a combination of factors: reduced blink rate when concentrating on screens, straining to focus on small print for extended periods of time and the high energy blue light emitted from digital screens causing eye discomfort.

Scratches or grit in the eye

Red eyes can be the result of a piece of grit getting in your eye. If there’s something in your eye, your optometrist will try to remove it with the assistance of an anaesthetic drop. Once a foreign body is removed, you may be given antibiotic eye drops and ointment to prevent an infection occurring during the healing process.


Receiving an eye injury may cause it to become red. Other symptoms that may occur with an eye injury are:

  • eye pain
  • swelling of the eye or the surrounding area
  • trouble moving your eye
  • decreased vision
  • different pupil sizes

Other causes of eye redness include:

  • use of alcohol or cannabis
  • eye irritation from sun exposure
  • ocular rosacea, a skin condition that most often affects the cheeks, nose, or forehead but can also affect your eyes
  • trichiasis, in which eyelashes grow inward and irritate the eye
  • retinoblastoma, a type of cancer that affects the eye
How can you prevent eye redness?

Some eye redness can be prevented by using proper hygiene and avoiding irritants that can cause redness.

You should also:

  • Wash your hands frequently, particularly if you’re exposed to someone who has an eye infection.
  • Remove all makeup from your eyes each day.
  • Don’t wear contact lenses longer than recommended or while swimming.
  • Don’t wear contact lenses overnight.
  • Clean your contact lenses regularly.
  • Avoid activities that can cause eyestrain.
  • Avoid contact with substances that can cause your eyes to become irritated. If exposure does occur, flush out your eye immediately with eyewash or water if eyewash isn’t available.
When should you see the optometrist?

Although red eye can go away on its own, sometimes your red eyes are a symptom of a more serious eye condition or disease.

Contact an optometrist if:

  • Your eyes are painful
  • Vision is affected
  • Eyes become extra sensitive to light
  • Symptoms have continued for a week or more, or are getting worse
  • The eye is producing a lot of pus or mucus
  • A fever or aches are also present with the eye discomfort
If your red eyes are accompanied by eye pain, light sensitivity, swelling, or blurry vision, it is important to make an appointment with an optometrist immediately.
The best and safest way to get rid of red eyes, is to see your optometrist to determine the cause of your bloodshot eyes and receive the most effective treatment options.

Until you can see your optometrist about your red eye problem, remove your contact lenses (if you wear them) and wear your glasses instead. Bring your contacts with you to your appointment so your optometrist can evaluate whether your contact lenses are causing your red eyes.