Red eyes are a common condition that can occur due to several reasons.

Eye redness, also known as conjunctival injection, is usually caused by dilation or inflammation of the blood vessels in the conjunctiva, a thin transparent layer that lines the inside of the eyelid and covers the white part of the eye. Eye redness can occur in one or both eyes, and it may or may not be accompanied by other symptoms like itching, burning, discharge, swelling, pain, sensitivity to light, and blurred vision.

Depending on the cause, eye redness may require medical attention. Here are some possible reasons for red eyes:.

Allergies

Allergies are a common cause of red eyes. This can occur when a person is exposed to allergens such as dust, pollen, animal dander, or mold spores.

The conjunctiva becomes inflamed in response to the allergen, and the blood vessels dilate, causing redness. Additionally, other symptoms like itching, tearing, and swelling may also occur in some individuals.

Eye Infection

An eye infection can cause redness. It is usually caused by bacteria, viruses, or fungi that enter the eye through contaminated hands, contact lenses, or makeup.

The conjunctiva becomes inflamed in response to the infection, and the blood vessels dilate, causing redness. Other symptoms like discharge, pain, and sensitivity to light may also occur in some cases. Common eye infections include conjunctivitis or pink eye, keratitis, and blepharitis.

Dry Eyes

Dry eyes occur when the eyes cannot produce enough tears or the quality of tears is poor.

This can be caused by several factors such as aging, hormonal changes, certain medications, environmental factors, and medical conditions like Sjogren’s syndrome, rheumatoid arthritis, and lupus. The lack of adequate lubrication can cause the conjunctiva to become inflamed and red. Other symptoms like burning, itching, and grittiness may also occur in some individuals.

Foreign Object

A foreign object such as dust, dirt, or an eyelash can get into the eye and cause redness. The object irritates the conjunctiva, and the blood vessels dilate, causing redness. Other symptoms like tearing, pain, and sensitivity to light may also occur.

It is important to remove the foreign object as soon as possible to avoid further irritation.

Eye Trauma

Eye trauma such as a blow to the eye or a scratch on the cornea can cause redness. The trauma can cause the conjunctiva to become inflamed, and the blood vessels to dilate, causing redness.

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Other symptoms like pain, swelling, and blurred vision may also occur. It is important to seek medical attention if the trauma is severe or if vision is affected.

Contact Lenses

Contact lenses can cause red eyes in some individuals. This can be due to several reasons such as wearing lenses that do not fit properly, wearing lenses for too long, using expired lenses, or wearing lenses while swimming or sleeping.

The lack of oxygen to the cornea and the irritation caused by the lenses can cause the conjunctiva to become inflamed, and the blood vessels to dilate, causing redness. Other symptoms like itching, burning, and discharge may also occur.

Glaucoma

Glaucoma is a serious eye condition that can cause redness. It occurs when the pressure inside the eye increases, causing damage to the optic nerve.

The conjunctiva becomes inflamed in response to the pressure, and the blood vessels dilate, causing redness. Other symptoms like blurred vision, halos around lights, and severe eye pain may also occur. Glaucoma requires immediate medical attention to prevent vision loss.

Uveitis

Uveitis is an inflammatory condition that affects the uvea, the middle layer of the eye that contains the iris, ciliary body, and choroid. It can cause redness, as well as other symptoms like pain, sensitivity to light, blurred vision, and floaters.

Uveitis can be caused by various factors such as infections, injuries, autoimmune disorders, and certain medications. It requires medical attention to prevent complications like cataracts, glaucoma, and vision loss.

Corneal Ulcer

A corneal ulcer is an open sore in the cornea, the clear layer on the front of the eye. It can be caused by bacterial, viral, or fungal infections, as well as by dry eyes, contact lens wear, trauma, and autoimmune disorders.

A corneal ulcer can cause redness, as well as other symptoms like eye pain, discharge, blurred vision, and sensitivity to light. It requires medical attention to prevent vision loss.

Conjunctival Hemorrhage

A conjunctival hemorrhage is a burst blood vessel in the conjunctiva, usually caused by a minor injury, coughing, sneezing, or straining. It can also occur spontaneously, especially in individuals with high blood pressure or blood clotting disorders.

A conjunctival hemorrhage can cause redness, but it usually resolves on its own within a few days without any complications.