A red eye is usually a sign of some type of ocular irritation, which can occur due to dry environments, cream or makeup use, or as a result of an allergic reaction. In these cases, washing the face and applying soothing eye drops to the affected eye can generally relieve symptoms.

Nonetheless, a red eye can also be caused by a more serious condition, like conjunctivitis or blepharitis.

Therefore, if you notice red eyes frequently, if it takes a long time to resolve, or if it is accompanied by other symptoms like pain, discharge or difficulty seeing, you should consult an ophthalmologist to identify the underlying cause and start treatment as necessary.

Why is my eye red?

Some common situations or conditions that can lead to red eyes include:

1. Foreign body

It’s common for a particle of dust or sand or other tiny object to enter contact with the surface of the eye. This can irritate the sclera and cause itchiness and discomfort.

What to do: Cleanse your eyes with saline or eye drops from the pharmacy to help eliminate the foreign body. It is important to avoid rubbing your eyes or putting your fingers directly on the eyeball, as this can increase the risk for infection.

2. Reaction to cream or make-up

Some people are more prone to reactions from make-up or creams, and these reactions can be noted in the eyes as well, with red eyes, irritation and tearing. This can especially occur when makeup or other products are used beyond their expiry date.

Eye shadow, liner, and mascara are the makeup products most likely to cause red eyes and irritation. Sun screen for the body should not be used on the face or near the eyes, for example, as it can irritate the eyes.

What to do: Wash the face with cold water and remove all remains of cream and makeup. Apply moisturizing eye drops or saline to the eyes, and keep them closed for a few minutes. A cold compress over the eyes can also help with swelling and irritation.

3. Scratched cornea or conjunctiva

Scratches to the cornea or conjunctiva are common situations that can leave the eyes red and irritated due to injury. This type of scratch can occur due to direct trauma to the eye, during a sports game, or after being attacked by a cat. It can also be a result of a foreign body in the eye.

What to do: To decrease discomfort, you should keep your eyes closed and wait a few moments before opening it slowly. In addition, you can apply a cold compress over the eye for a few minutes, and use sunglasses to protect the eye from the sun‘s rays. If you suspect you have injured your cornea or conjunctiva, you should see an ophthalmologist for assessment and treatment as necessary.

4. Dry eye syndrome

People who work many hours in front of a computer or spend a lot of time watching TV or using their cell phone have a higher chance of having dry eye syndrome. This is a condition that can leave the eyes reddened and irritated, especially at the end of the day, due to the a decrease of tear production.

What to do: To relieve symptoms of dry eye syndrome, you should make an effort to blink frequently when in front of a screen. You can use eye drops or artificial tears throughout the day when you start to feel eye discomfort.

5. Pink eye

Pink eye, also known as conjunctivitis, is an inflammation of the membrane that lines the eyelids and surface of the eye. It can cause symptoms like red eyes, light sensitivity, itching, and yellow crust, which can affect just one eye.

This inflammation is usually caused by a virus, but it can also occur due to bacteria or an allergy.

What to do: If you suspect conjunctivitis, it is important to consult an ophthalmologist to identify the cause of it and to start treatment. Treatment can include antibiotic or antiallergenic eye drops, or artificial tears. It is important to keep your eyes clean and free of discharge.

Depending on the cause, conjunctivitis is an infection that is easily transmitted to others. Therefore, you should ensure adequate hand hygiene with soap and water. Particularly after cleaning the eyes or coming in contact with the discharge.

6. Blepharitis

Blepharitis is an inflammation of the eyelids that leaves the eyes red and irritated. It can also cause small cysts that make opening the eyes difficult when waking. This is especially true if the blepharitis is caused by an abnormality in the Meibomian glands.

What to do: Treatment for blepharitis consists of keeping the eyes clean. You may need to wash your face and eyes with a mild kids‘ shampoo so that you can properly wash the eyes without burning them.You can then apply a warm compress over the eyes. Ideally, the blepharitis should be assessed by an ophthalmologist, as it may be caused by a bacterial infection that requires more targeted treatment.

7. Uveitis

Uveitis is an inflammation of the uvea of the eye which can cause symptoms very similar to conjunctivitis. These include a red eye, light sensitivity, crust and pain. Uveitis is not as common as conjunctivitis and mainly occurs in people with other conditions, especially autoimmune diseases (like rheumatoid arthritis of Behcet's disease) or infectious diseases (like toxoplasmosis, syphilis or AIDS).

What to do: You should consult an ophthalmologist for diagnosis and treatment, which is aimed at reducing inflammation and healing through anti-inflammatory drops and corticosteroids.

8. Keratitis

Keratitis is an inflammation of the external part of the eye, known as the cornea. It commonly occurs in people who use contacts incorrectly , as it favors the growth of fungus and bacteria on the outermost layer of the eye.

The most common symptoms of keratitis include red eyes, pain, blurry vision, excessive tearing and difficulty opening the eye.

What to do: You should consult an ophthalmologist to confirm a diagnosis, identify the underlying cause, and start appropriate treatment, which may include antifungal or antibiotic eye drops or ointments.

9. Glaucoma

Glaucoma is an ocular disease that is most times caused by increased pressure within the eye. This pressure gradually worsens over months to years. There are some types of glaucoma that can cause red eyes, like glaucoma secondary to retinopathy from diabetes.

Glaucoma is most common in people over 40, who have a positive family history of it.

What to do: Ideally, glaucoma should be identified in its initial stages, before symptoms start to emerge, as symptoms are easier to manage and complications like blindness can be prevented. Therefore, you should regularly see an ophthalmologist for check-ups. If a diagnosis is confirmed, treatment can be done with special eye drops that reduce pressure within the eye.

When to see a doctor

It is important to see a doctor or go to the hospital if you frequently notice red eyes and it does not resolve with time. This an be a sign of a very serious eye condition.

You should seek immediate medical attention if:

Your eyes become very red becomes a possible perforation
You have a headache and blurry vision
You experience confusion and do not know who you are or where you are
You are nauseous or vomiting
The eyes are red for more than 5 days
You suspect you may have something in your eye
You are having yellow or green discharge from the eyes

In these cases, you should be assessed by an ophthalmologist for testing and assessment, so that treatment can be initiated.