By Eyecare NG

Overview   |  Causes   |   What to do 


Red eye is a term used mostly to describe red, sore and bloodshot eyes. It occurs as a result of the dilation and engorgement of the blood vessels of the conjunctiva (the outer covering of the eye) and/or the sclera (the white part of the eye).

Red eye is a common symptom of eye problems. Eye care service providers from day to day see patients with complaint of red eye.

Most of us have experienced red eye at some point in our lives. It may have involved one or both eyes, may have appeared suddenly or developed over time and may have even resolved on its own without treatment.

While some cases of red eye resolve without treatment, it can be a symptom of a serious eye condition. Therefore, it is important that you see an eye care professional when you have red eyes that get worse or fail to resolve within few hours.

Causes of Red Eye

There are many causes of red eye ranging from minor conditions to vision-threatening conditions. The common causes include infection, inflammation, allergy and injury. In addition to red eye, these conditions may present with pain, light sensitivity, discharges, tearing, foreign body sensation, swelling and blurry vision.

Infection and Inflammation

An eye infection is a disease that is caused by the invasion of the eye tissues by germs. Inflammation, on the other hand, is a condition of the eye characterized by swelling, pain, redness and heat. While inflammation commonly occurs as a result of infection and injury, it may not have a specific cause in some cases.

Some infection/inflammatory conditions that have red eye as a symptom include:

  • Conjunctivitis – Inflammation of the conjunctiva (the thin, transparent covering of the sclera and lining of the inner part of the eyelids).
  • Keratitis – Inflammation of the cornea (the clear tissue covering the coloured part of the eyes)
  • Blepharitis – Inflammation of the eyelids
  • Iritis – Inflammation of the iris (the coloured part of the eyes
  • Sclera – Inflammation of the sclera (the white part of the eyes)


This is a condition that occurs as a result of a person’s sensitivity to allergens. These allergens are substances that are capable of triggering abnormal immune reactions in the body. They include pollen, dust, animal fur/hair, grass and some medications.

Red eye due to allergy is normally accompanied by itching and swollen lids.

Some allergic conditions are seasonal. Hence, susceptible persons are advised to avoid or minimize exposure to known allergens and also have the anti-allergic medications prescribed by their doctor handy during the seasons.

Dry Eye

This is a condition in which the surface of the eye dries out due to insufficient tears, insufficient blinking or prolonged exposure of the eyes in an airy and windy environment. Dry eyes can cause red eye.

In this era of heavy computer and other digital device use; computer vision syndrome has become a major factor in dry eyes and red eyes. This is because most computer and digital device users do not blink sufficiently while working on their devices.


Physical injuries to the eye normally cause red eye. This may be associated with other symptoms such as swelling, pain, heat, a reduction in vision and a black eye (that occurs if blood vessels get broken and leak blood under the surrounding skin).

Chemicals and Foreign Bodies

If chemical substances and foreign materials (like sand) get into the eye, they can cause red eye. Severe damage can be done to the eye if the chemical substance is alkaline in nature. This is because alkaline substances penetrate deeper into the eye than most acidic substances. Therefore, the first thing to do if your eyes get exposed to any chemical is to flush it with plenty of clean water. Flushing your eyes with water removes chemical in the eye and limits its penetration into the deeper parts of the eye.


Glaucoma is a group of eye diseases characterized by progressive optic nerve damage and visual field loss. If left untreated, glaucoma can lead to permanent loss of vision. Red eye in glaucoma usually occurs when the pressure in the eye suddenly goes up to very high levels. Other symptoms experienced include severe eye pain, tearing and blurry vision. The person may also have headaches and sees haloes (rainbow-like colours around light).

Glaucoma is a very serious eye condition. It has no cure but can be managed successfully with continuous professional care.

Contact Lens Misuse

Contact lenses are medical devices used in the correction of refractive errors. They are placed directly in the eye on the cornea. Improper handling and over wear of contact lenses can irritate the eyes and result in red eyes. To avoid complications with contact lens use, it is recommended that contact lens wearers adhere to doctor’s instructions on the use, care and replacement of their lenses.

Subconjunctival Haemorrhage

This is bleeding under the conjunctiva. It appears as a bright or dark red batch on the sclera. It occurs when there is a rupture of the blood vessels that supply the conjunctiva. This rupture could be caused by any condition that weakens the blood vessels or increases the pressure of blood flowing into them. Some factors that may play a role in subconjunctival haemorrhage include constipation, excessive coughing, strenuous exercises, physical injury, suffocation and use of some blood thinners such as warfarin and aspirin.

Other causes of red eye include lack of sleep, smoking, alcohol and some drugs such as marijuana and cocaine.

What to Do When You Have Red Eye

Treatment and care given to red eye depend on the cause and other associated factors. Sometimes, red eye clears on its own without any treatment. In some cases rest, cold compress and behavioural changes are all that is required. In other cases, medications and even surgical care may be required.

  1. If you have red eyes due to prolonged use of computer and other digital devices, it is advised that you make effort to consciously blink periodically and adopt the 20:20:20 rule while using your devices. With the 20:20:20 rule, every 20 minutes of digital device use, you should look at an object 20 feet away and blink for 20 seconds.
  2. If you experience red eye with contact lens use, remove them immediately, wash them with the right solution, store them properly and give your eyes some rest before resuming lens wear. Remember to adhere the replacement schedule for your contact lenses.
  3. If you have red eye that gets worse or does not resolve within a few hours, consult your eye doctor.
  4. If you have red eye associated with purulent discharges or severe pain, headache, blurry vision, and light sensitivity, consult your eye doctor immediately.
  5. Avoid self-medication as this can lead to complications including vision loss and blindness.