red eyes

Red Eyes – Causes, Symptoms, Treatment and Prevention

Bloodshot or red eyes occur when blood vessels on the surface of the eye congested or bleed.

It is not normal for eyes to be red.

The common causes are not sight or life threatening, however some causes of red eye can point to a serious medical issue.

Causes of Red Eyes


Conjunctivitis is a common eye problem, and refers to inflammation of the conjunctiva. The conjunctiva is a clear lining of the white of the eye (the sclera) which loops around to cover the back of the eyelids. As the conjunctiva is very thin and exposed to the environment, it can become inflamed or infected easily. The irritation of the surface blood vessels causing them to swell up. This inflammation makes the eye look red or pink, instead of white.

red eyes

Conjunctivitis can be caused by infection, inflammation or allergy.

“Pink eye” refers to infective conjunctivitis, usually by either a virus (causing up to 80% of all cases) or bacteria. Signs include redness and inflammation of the white part around your eyes, making them look “pink.” Viral conjunctivitis is highly contagious due to its transmission through direct contact. You can easily get infected when you come in close proximity with an infected child or adult.

Allergic conjunctivitis can be due to allergens such as pollen, or irritants such as dust.

Wearing contact lenses for too long and not properly cleaning them may also lead to conjunctivitis due to irritation or reduced oxygen supply. Conjunctivitis through contact lenses is a common non-contagious infection of the eyes caused by irritation. It can cause reduced vision in severe cases.

Symptoms of conjunctivitis include:

  1. Eye redness
  2. Eye watering
  3. Discharge – could be watery, mucus or pus
  4. Itchy eyes
  5. Light sensitivity
  6. Poor vision
  7. Gritty feeling in one or both eyes

Treatment depending on the cause of infection. Viral conjunctivitis resolves over days to weeks, and it is important to practice proper hand hygiene and social distancing to reduce transmission and infection of other individuals. Bacterial conjunctivitis requires antibiotic eye drops. Allergic conjunctivitis is treated with anti-allergy drops and tablets, as well as avoiding the allergens that trigger the response.

Corneal Ulcer:

A corneal ulcer is an open sore on the cornea that can lead to blindness if left untreated.

It is usually caused by a bacterial infection and this can occur following eye trauma, contact lens wear or following eye surgery. Eyelid disorders and the cold sore virus (herpes simplex virus) can also cause corneal ulcers. Other causes of corneal ulcers include parasites, fungi, facial palsy (“Bell’s palsy”) and severe dry eyes.  

Symptoms of Corneal Ulcers:

  1. red eyes
  2. reduced vision
  3. pain in the eye
  4. sensitivity to light
  5. mild to severe eye discharge
  6. a white spot on the cornea
  7. soreness of the eye

Prescription medications and close follow up are required for the treatment of a corneal ulcer.

Dry Eyes:

A person who has reduced tear production, or rapid tear evaporation, can experience dry eyes. This condition, known as Dry Eye Syndrome (DES), is a very common eye problem around the world.

Dry eyes can be caused by many factors, including work-related stress or reduced tear production, which leads to insufficient moisture for healthy functioning. People suffering from this chronic ailment may feel constantly uncomfortable with eye redness, stinging sensation, burning pain behind the eyelid, and (somewhat surprisingly) excessive tearing.

Dry eye can be caused by an underlying medical condition or just as a result of reduced gland function in older age. It is difficult to determine the cause without visiting your doctor and getting tested for dry eyes.

Symptoms of dry eye syndrome include:

  1. stinging or burning eyes
  2. foreign body sensation
  3. pain and redness in the eye
  4. excessive tearing
  5. blurry vision
  6. eye fatigue
  7. stringy eye discharge
  8. increased discomfort after watching television or reading (due to reduced blinking during these activities)

For mild cases, artificial tears might help supply some lubrication. More severe conditions require prescription medications, and sometimes surgery.

Subconjunctival Haemorrhage:

The conjunctiva is the thin membrane that covers and protects your eye. Many blood vessels in this area can burst and cause a subconjunctival haemorrhage when their lining is broken. There will be a small amount of bleeding under the outer layer of membranes when it does happen. This causes a small or large bright red patch to appear.

It is common for people not to know why they suddenly have a subconjunctival haemorrhage. It often occurs due to minor injury or trauma, such as rubbing the eye too hard. Straining also has been reported in some cases and can be caused by coughing, sneezing or constipation. It is more common in patients who are on aspirin or blood thinning medications. However, many times doctors are unable to determine what triggered this type of bleeding under the eyelid even after investigation.

Symptoms of Subconjunctival Haemorrhage:

  1. When bleeding first occurs, you may experience a full feeling in the eyes.
  2. mild eye irritation
  3. Red patch on eyes

Subconjunctival haemorrhage resolves on its own over a few weeks. The blood can spread initially and become larger in the first 24 hours. The colour changes to yellow before disappearing completely. No medications are required.


Glaucoma is a condition that causes damage to the optic nerve due to pressure build-up in the eye. The front part of your eyes contains clear fluid, called aqueous humour. This fluid nourishes your eye. There are many causes of glaucoma, however a sudden build-up of pressure can occur due to “acute angle closure”, when fluid can no longer drain out of the eye.

The symptoms of acute glaucoma are:

  1. eye redness
  2. eye pain, usually severe
  3. seeing halo-like glows around lights
  4. blurred vision
  5. nausea and possibly vomiting

Other causes of red eyes:

These are just a few common disorders associated with red eyes. Others include:

  1. inflammation of the cornea (keratitis), iris (iritis or uveitis), or white of the eye (scleritis)
  2. too much sun exposure
  3. dust or other particles in the eye
  4. injury
  5. swimming
  6. smoking or drinking
  7. environmental irritants or pollutants

Treatment of Red eyes

The treatment for red eyes depends upon its cause and seriousness. Sometimes just giving your eyes rest or gently massaging over the eyelids can help. Washing your eyes and eye drops can also be used to treat red eyes. Your doctor may also prescribe you some eye drops or ointment.

Prevention of Red eyes

Follow these tips to prevent red eyes:

  1. You should wash your hands if you’ve come in contact with someone who has an eye infection.
  2. Always remember to remove eye-makeup before going to bed.
  3. Avoid wearing contact lenses for too long, generally not more than 12 hours per day.
  4. Clean your contact lenses regularly.
  5. Stay away from daily activities that put pressure on your eyes.
  6. Avoid substances that can cause allergies.


Red eyes are often harmless and usually go away on their own. However, if you have constant eye redness, associated pain, discharge or reduced vision, it is best to consult an eye doctor. An eye doctor will help detect its cause and provide appropriate treatment before it becomes serious.

As an ophthalmologist in Canberra, Dr Parth Shah is committed to providing excellent eye care service for his patients with modern research and the latest technology.