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Red eyes: Causes, Symptoms, Diagnosis, and Treatment

Red eyes (aka bloodshot eyes) is a condition in which the eyes appear red. Red eyes can be caused due to mechanical irritants, infections, environmental irritants, medical conditions or allergic reaction. In most cases, the condition is mild and gets resolved on its own. However, severe cases may need immediate treatment.

Red EyesWhat is Red eye?

A red eye is a condition in which the surface of the eye (sclera) may have several red lines or diffused red color. This condition occurs due to dilated or swollen blood vessels. The redness is mostly benign, which disappears in 7 to 10 days. But in some cases, where the redness is associated with pain and change in vision and, indicates a serious eye problem and requires medical intervention.

Causes of Red eyes:

Red eyes are mainly caused due to inflamed blood vessels between the sclera and the conjunctiva (thin, transparent layer covering the white part of the eye). The inflammation of the blood vessels can be due to some specific irritant or any other eye condition. The following are the causes of red eyes.

Eye conditions: The eye conditions that can lead to red eyes include:

  • Dry eyes: The reduced tear production causes dry eyes that make the blood vessels inflamed and irritated. Dryness can be due to dry weather, use of contact lens for a long time, lack of sleep, or conditions like arthritis, diabetes, pregnancy or menopause.
  • Eye allergies: The eye irritants can cause inflammation of the blood vessels, which can lead to eye allergies. Some of the irritants causing red eyes include dust, exposure to sun, bacteria or virus, pollen, pet dander, chlorine, smoke or contact lens.

Eye infections: Bacterial, viral, helminths or fungal infections can lead to red eyes. Eye infections can be caused by the use of cosmetic products or contact lens. The following are some of the common eye infections that cause red eyes.

  • Conjunctivitis: It is the infection of the conjunctiva caused by bacteria or viruses.
  • Blepharitis: It is a non-contagious, scaly infection of the eyelids.
  • Sty: It is an infection of the eyelash follicles where a small bump appears on the base of the eyelash or the eyelids.
  • Preseptal cellulitis: It is a bacterial, viral, fungal or helminth infection where the eyelids and the surrounding skin gets swollen.
  • Uveitis: It is the inflammation of the uvea, the middle layer of the eye.
  • Corneal ulcers: It is a bacterial or viral infection where painful sores appear on the cornea, the protective outer layer of the eye.

Other causes of red eyes include glaucoma (damage of the optic nerve), chemical burns, recent eye surgery, use of drugs and alcohol.

Signs and Symptoms of Red Eyes:

Red eyes may occur in both or one eye. In some cases, the condition may have no other symptoms except redness. Whereas, most often the condition is associated with the following symptoms:

  • Dryness
  • Discharge
  • Pain
  • Irritation
  • Burning sensation
  • Watery eyes
  • Light sensitivity
  • Itching
  • Blurry vision

Diagnosis of Red Eyes:

Before initiating the treatment, it is essential to diagnose the underlying cause of red eyes. The doctor can diagnose the condition by obtaining a detailed history from the patient and carefully examining the eye.

The doctor will ask for the history of the following:

  • Duration of symptoms
  • Severity of pain
  • Unilateral or bilateral eye involvement
  • Amount and type of discharge
  • Presence of visual change
  • Use of contact lens
  • Any previous treatment
  • Presence of allergies or systemic diseases
  • Photophobia

The doctor will examine the following to diagnose the underlying cause:

  • Pupil size
  • Pupils reaction to light
  • Eyelids
  • Corneal involvement
  • Pattern and location of hyperemia (increased blood flow in the blood vessels)
  • Lacrimal sac

In severe cases of red eyes, specific laboratory tests are performed, like the tear osmolarity test to diagnose dry eyes.

Treatment for Red Eyes:

According to the diagnosis, the doctor will decide the treatment method to reduce the symptoms. The treatment options include:

  • Medications: In severe cases, the doctor may prescribe antibiotic therapy to cure eye infection caused by bacteria.
  • Eye drops: Most medicines for eye conditions are in the form of drops. These drops must be taken according to doctor’s prescription. Some of the eye drops prescribed to treat different conditions are:
    • Anti-redness: It is used to reduce the redness.
    • Antibiotic eye drops: They are prescribed for an eye infection.
    • Naphazoline or tetrahydrozoline eye drop: It is a decongestant used to treat allergic reaction or irritation.
    • Glaucoma drops: These are used to reduce pressure in the eyes.
    • Eye lubricant drop: These are used to treat dry eyes.
  • Eye patches: In cases where the eyes are extremely irritated, the doctor may advise eye patches to protect the eyes from light and accelerate the healing process.


The following measures may help to prevent red eyes:

  • Maintain proper hygiene: Always wash hands with soap and warm water, before touching the eyes. In case something reaches the eye, rinse it to flush out the irritants.
  • Cosmetics: Remove all the eye makeup before sleeping and use good quality eye makeup.
  • Contact lenses: Clean the contact lenses before wearing them. If the contact lenses are irritating, do not wear them for a few days.
  • Eyestrain: Avoid doing activities that can strain the eyes.
  • Avoid irritants: Protect eyes from eye irritants, such as pollen, smoke, dust, microbes, etc.


Eye Redness . Medline Plus. Accessed on December 8. Accessed December 8, 2018.
Diagnosis and Management of Red Eye in Primary Care . American Family Physician . Accessed December 8, 2018.

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