What Causes Red Eyes?

Red eyes occur when the blood vessels on the surface of the eye or inside the eyelids become dilated or irritated. The redness can affect one or both eyes, appear suddenly or gradually, and range from a faint pink tinge to vivid crimson depending on the underlying cause.

At Upper West Optical, we see patients with red eyes regularly and help them understand whether their redness is a minor issue that will resolve on its own or a symptom requiring prompt professional attention.

Common Everyday Causes

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Dry Eye

Insufficient tear film lubrication leaves the eye surface exposed and irritated. The resulting inflammation causes blood vessel dilation and persistent redness that worsens throughout the day and in dry or air-conditioned environments.

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Allergies

Seasonal and perennial allergens trigger histamine release in the eyes, causing the classic combination of intense itching, watering, and redness that typically affects both eyes simultaneously.

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Fatigue and Sleep Deprivation

Insufficient sleep reduces tear production and increases eye surface exposure during longer waking hours, producing redness, irritation, and a heavy feeling in the eyes that resolves with adequate rest.

Conditions Requiring Medical Attention

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Bacterial Conjunctivitis

Bacterial pink eye causes redness with a thick yellow or green discharge, particularly noticeable in the morning. It is highly contagious and typically requires antibiotic eye drops to resolve properly.

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Viral Conjunctivitis

The most common form of pink eye, caused by viruses including adenovirus. It produces redness with a watery discharge, often starting in one eye before spreading to the other, and resolves on its own over one to two weeks.

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Subconjunctival Hemorrhage

A broken blood vessel beneath the conjunctiva creates a vivid bright red patch on the white of the eye. It looks dramatic but is usually harmless and resolves without treatment within one to two weeks.

      When Red Eyes Need Same-Day Evaluation
      Redness combined with significant eye pain, especially if sudden in onset
Redness with vision changes, blurring, or halos around lights
Contact lens wearers with redness that does not improve after removing lenses
Redness following an eye injury, chemical exposure, or foreign body entry
Redness with thick discharge and significant crusting in a newborn or young child
Redness that is worsening despite removing contact lenses and resting the eyes

    

Less Common But Important Causes

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Acute Glaucoma

Acute angle-closure glaucoma causes sudden redness along with severe pain, nausea, and halos around lights. This is a medical emergency that can cause rapid permanent vision loss without immediate treatment.

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Contact Lens Overuse

Wearing contact lenses for too long or in poor condition causes oxygen deprivation and mechanical irritation to the cornea, producing redness that persists until the lenses are removed and the eye has time to recover.

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Uveitis

Inflammation of the uvea, the middle layer of the eye, causes a distinctive pattern of redness concentrated around the iris. It often occurs with light sensitivity and pain and requires prompt specialist evaluation and treatment.

Managing Common Red Eye Causes at Home

For redness caused by mild dryness, fatigue, or minor irritation, preservative-free artificial tears, rest, and removing contact lenses often resolve the issue within a day. Applying a cool compress to closed eyelids can reduce inflammation and provide temporary comfort.

If redness persists beyond a few days, affects only one eye, is accompanied by discharge, or involves any pain or vision changes, a professional evaluation at Upper West Optical will identify the cause and ensure the most appropriate treatment is started promptly.