Red eye

Red eye is a symptom rather than a disease. It happens when small blood vessels on the eye's surface widen or, less often, leak. The redness may cover most of the white of your eye or appear as a single bright-red patch.

Many red eyes come from irritation, dryness, allergy, or conjunctivitis. Conjunctivitis is inflammation of the thin, clear layer covering the white of the eye and inner eyelids. Some causes need prompt care, especially when redness comes with pain, sensitivity to light, or a change in vision.

Your eye may look pink, bloodshot, or intensely red. One or both eyes may be affected. Other symptoms can give clues about the cause:

• Itching and watering often occur with allergies
• A gritty or burning feeling can occur with dry eye or conjunctivitis
• Sticky discharge may make the eyelids cling together
• Crusting around the eyelashes can occur with eyelid inflammation
• A bright-red patch without pain may be a small surface bleed
• Deep pain, light sensitivity, or blurred vision can suggest a more serious problem

Discharge can briefly blur your sight, but it should clear after blinking or gently wiping the eyelids. Blurring that continues, or any other loss of vision, needs urgent assessment.

Conjunctivitis can be caused by a virus, bacteria, or an allergy. Viral conjunctivitis often starts in one eye before spreading to the other and may occur with a cold. Bacterial conjunctivitis can cause thicker discharge. Allergic conjunctivitis usually affects both eyes and is often very itchy.

Dry eye happens when the eyes do not make enough tears or the tears evaporate too quickly. It can cause burning, grittiness, watering, and redness. Screens, dry air, wind, and some medicines may make it worse.

Blepharitis is inflammation around the eyelid edges. It may cause crusty eyelashes, irritated lids, and a gritty feeling. Symptoms often come and go.

Smoke, dust, chlorine, cosmetics, rubbing, and lack of sleep can also irritate the eye. A small broken surface blood vessel can create a sharply defined red patch. This usually looks more concerning than it feels and should not cause pain or affect vision.

Less common causes include a scratch on the clear front surface of the eye, a trapped object, or inflammation inside or around the eye. Infection of the cornea, called keratitis, is particularly important in people who wear contact lenses.

Rare but urgent causes include acute angle-closure glaucoma, which causes a sudden rise in eye pressure, and serious inflammation inside the eye. These usually cause more than redness alone.

Seek emergency care now if:

• A chemical has splashed into your eye
• An object has pierced the eye or is firmly embedded
• You suddenly lose vision
• Redness comes with severe eye pain, headache, vomiting, or rainbow-coloured halos

After a chemical splash, immediately rinse the eye continuously with plenty of clean, lukewarm water while arranging emergency help. Do not try to remove an embedded object or press on an injured eye.

Arrange a same-day assessment for a red eye with pain, sensitivity to light, or blurred or reduced vision. You should also seek same-day care after an eye injury, if something may be trapped in the eye, or if one pupil looks different from the other.

If you wear contact lenses, remove them and seek same-day advice for a red, painful, light-sensitive, or unusually watery eye. Contact lens wear can increase the risk of corneal infection. A newborn with a red or discharging eye also needs prompt medical assessment.

For mild symptoms without these warning signs, book a routine appointment if the redness lasts longer than about a week, keeps returning, is getting worse, or produces ongoing discharge. Persistent dryness or eyelid irritation can also be discussed at a routine visit.

A clinician will ask when the redness began, whether it affects one or both eyes, and whether you have pain, discharge, itching, light sensitivity, injury, or vision changes. Mention contact lens use, recent eye surgery, new eye products, allergies, and anyone nearby with similar symptoms.

The examination may include checking your vision, pupils, eyelids, and eye movements. A special microscope called a slit lamp can provide a magnified view. Fluorescein, a harmless orange dye, may be used to reveal a scratch or corneal damage. Eye-pressure testing or a discharge sample is sometimes needed.

Treatment depends on the cause. Antibiotic drops only treat certain bacterial infections; they do not help viral or allergic conjunctivitis. Other conditions may require allergy treatment, lubricating drops, antiviral medicine, or urgent specialist care.

For mild irritation while arranging advice:

• Avoid rubbing or touching your eyes
• Wash your hands before and after touching the eye area
• Use a clean, cool compress for itching or watering
• Use a warm compress for crusty eyelid edges
• Consider plain lubricating eye drops for dryness
• Avoid contact lenses until symptoms have fully resolved or you are cleared to restart them
• Do not share towels, cosmetics, eye drops, or contact lens equipment

Do not use leftover prescription drops. In particular, steroid eye drops can worsen some infections and should only be used under professional supervision. Drops marketed mainly to remove redness can sometimes cause more redness when their effect wears off.

Clean discharge from the eyelids with fresh water and a clean pad. Use a separate pad for each eye. If symptoms may be infectious, careful handwashing helps reduce spread.

Simple irritation may settle after the trigger is removed. Viral conjunctivitis often improves over one to two weeks but can last longer. Allergy symptoms may continue while you remain exposed to the trigger. Dry eye and blepharitis commonly improve and return over time.

A small surface bleed usually changes colour and clears gradually over a week or two. It should not cause pain or vision loss. Seek advice if these patches recur, follow an injury, or occur with unusual bleeding or bruising elsewhere.

Is every red eye conjunctivitis?

No. Dryness, eyelid inflammation, allergy, injury, surface bleeding, and conditions inside the eye can all cause redness.

Is red eye contagious?

Viral and some bacterial forms of conjunctivitis can spread through contaminated hands and objects. Allergic conjunctivitis, dry eye, and surface bleeding are not contagious.

Can screen use make my eyes red?

Long periods of screen use can reduce blinking, allowing tears to evaporate. Taking regular screen breaks and using lubricating drops may help if dryness is the cause.

Can I wear contact lenses?

Do not wear them while your eye is red or irritated. Pain, light sensitivity, watering, or blurred vision in a contact lens wearer needs same-day assessment.

Should I cover the eye with a patch?

Usually not. Patching can trap moisture and may worsen some infections. An injured eye should be protected only as directed by an emergency or eye-care professional.