Differential Diagnosis for Eye Redness and Pain with Tears

• Single most likely diagnosis
  • Conjunctivitis: This is the most common cause of eye redness and pain, often accompanied by tearing. It can be viral, bacterial, or allergic in nature, and the presentation of redness, pain, and tearing is consistent with this diagnosis.
• Other Likely diagnoses
  • Dry Eye Syndrome: Although it might seem counterintuitive, dry eye syndrome can cause eye pain and redness, and sometimes patients might experience tearing as a reflex to the irritation.
  • Corneal Abrasion: A scratch on the cornea can cause significant pain, redness, and tearing. The pain is often described as sharp or stabbing.
  • Blepharitis: Inflammation of the eyelids can lead to redness, itching, and sometimes pain, along with tearing due to irritation.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Acute Angle-Closure Glaucoma: This is a medical emergency that presents with sudden onset of severe eye pain, redness, blurred vision, and tearing. It requires immediate treatment to prevent permanent vision loss.
  • Endophthalmitis: A severe infection within the eye that can occur after surgery, injury, or blood infection. Symptoms include severe eye pain, redness, decreased vision, and swelling.
  • Orbital Cellulitis: An infection of the tissues surrounding the eye, which can cause pain, redness, swelling, and tearing, along with fever and general malaise.
• Rare diagnoses
  • Scleritis: Inflammation of the sclera (the white part of the eye), which can cause severe pain, redness, and tearing. It's less common than other conditions but can be associated with systemic diseases.
  • Uveitis: Inflammation of the uvea (the middle layer of the eye), which can cause pain, redness, sensitivity to light, and vision problems. It can be associated with systemic diseases or occur independently.