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Last updated: October 31, 2025View editorial policy

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Differential Diagnosis for a Swollen Red Eye

Single Most Likely Diagnosis

  • Conjunctivitis: This is the most common cause of a swollen red eye, often due to viral or bacterial infections. It presents with redness, swelling, and discharge.

Other Likely Diagnoses

  • Blepharitis: Inflammation of the eyelids can cause redness and swelling, often associated with itching and burning sensations.
  • Dry Eye Syndrome: Chronic dryness can lead to inflammation and redness of the eye, though swelling is less common.
  • Allergic Conjunctivitis: An allergic reaction can cause redness, itching, and swelling, especially in individuals with known allergies.
  • Corneal Abrasion: A scratch on the cornea can cause pain, redness, and swelling, often accompanied by sensitivity to light.

Do Not Miss Diagnoses

  • Acute Angle-Closure Glaucoma: A medical emergency that presents with severe eye pain, redness, and swelling, along with blurred vision and nausea. Missing this diagnosis can lead to permanent vision loss.
  • Endophthalmitis: A severe infection within the eye that can cause pain, redness, and swelling, often following eye surgery or trauma. It requires immediate treatment to preserve vision.
  • Orbital Cellulitis: An infection of the tissues surrounding the eye, which can cause swelling, redness, and pain, and may lead to serious complications if not promptly treated.

Rare Diagnoses

  • Keratoconus: A progressive thinning of the cornea that can cause vision problems and may lead to redness and swelling in advanced stages.
  • Scleritis: Inflammation of the sclera (the white part of the eye), which can cause severe pain, redness, and swelling, and is often associated with systemic autoimmune diseases.
  • Uveitis: Inflammation of the uvea (the middle layer of the eye), which can cause pain, redness, and swelling, and may be associated with systemic diseases or infections.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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