Red eyes are a very common symptom, sometimes accompanied by discomfort. Master, Doctor Phung Van Thanh from the High-Tech Eye Center at Tam Anh General Hospital Hanoi, states that several conditions can cause red eyes.

Conjunctivitis

Conjunctivitis is an inflammation of the thin membrane covering the white part of the eye and the inside of the eyelids. When blood vessels in the conjunctiva dilate, the eyes become red or pink, hence the condition is commonly known as pinkeye.

The three most common causes are viruses, bacteria, and allergies. Although all cause red eyes, each cause has different accompanying symptoms. Viral conjunctivitis often causes watery eyes, a gritty sensation, and can be contagious. Bacterial conjunctivitis typically presents with significant discharge. In contrast, allergic conjunctivitis usually causes itchy, watery eyes and is not contagious.

A patient with red eyes due to conjunctivitis. Photo: Tam Anh General Hospital

Keratitis

Keratitis is an inflammation of the transparent tissue at the front of the eye, which can be caused by bacteria, viruses, fungi, parasites, or non-infectious injuries. It often causes redness, pain, watery eyes, a foreign body sensation, light sensitivity, and blurred vision.

Unlike typical conjunctivitis, keratitis can directly affect vision. If treatment is delayed, especially in severe infections, the condition can lead to corneal damage and permanent vision loss.

Uveitis

Uveitis is an inflammation of the internal structures of the eye. It can cause red eyes, eye pain, blurred vision, and light sensitivity. Uveitis symptoms can appear rapidly within a few hours or days, or sometimes develop gradually. Delayed treatment increases the risk of complications that can permanently affect vision.

Acute glaucoma

Acute glaucoma, especially an acute angle-closure attack, can cause severe red eyes accompanied by eye pain, headache, blurred vision, nausea, or vomiting. This is one of the dangerous causes of red eyes because high intraocular pressure can damage the optic nerve if not treated promptly. Patients should seek immediate medical attention if red eyes are accompanied by severe headache and nausea.

Dry eyes

Dry eyes are one of the common causes of red eyes, occurring when tears are insufficient in quantity or quality to maintain a healthy eye surface. Patients may experience red, burning, gritty, watery eyes, or temporary blurred vision.

While generally not as dangerous as keratitis or acute glaucoma, persistent dry eyes still require evaluation to identify the cause and determine appropriate treatment.

Blepharitis

Blepharitis is a common cause of red eyes but is often mistaken for conjunctivitis. Individuals with blepharitis may experience red, itchy, gritty, burning eyes, along with crusting along the eyelid margins.

Subconjunctival hemorrhage

If a bright red, well-defined patch appears on the white of the eye, the cause may be a subconjunctival hemorrhage. This condition occurs when a small blood vessel beneath the conjunctiva ruptures, causing blood to spread and form a distinct red area.

Unlike conjunctivitis, a subconjunctival hemorrhage typically does not cause severe pain, excessive discharge, or significant vision impairment. However, if red eyes appear after trauma or are accompanied by pain or blurred vision, patients should consult a specialist to determine the cause and rule out more serious injuries.

Minh Duong