Itchy Eye Differential Diagnosis

The differential diagnosis for an itchy eye can be organized into the following categories:

• Single Most Likely Diagnosis

  • Allergic conjunctivitis: This is the most common cause of itchy eyes, often associated with other allergic symptoms such as sneezing, runny nose, and nasal congestion. It occurs due to an allergic reaction to substances like pollen, dust mites, or pet dander.

• Other Likely Diagnoses

  • Dry eye syndrome: This condition can cause itchiness, especially if the eyes are not producing enough tears or if the tears are of poor quality. It's common in people who stare at screens for long periods, wear contact lenses, or have certain medical conditions.
  • Blepharitis: Inflammation of the eyelids can cause itchiness, redness, and a gritty sensation in the eyes. It's often associated with poor eyelid hygiene, makeup use, or certain skin conditions like rosacea.
  • Conjunctivitis (viral or bacterial): While not always itchy, some forms of conjunctivitis can cause itchiness along with redness, discharge, and a feeling of grittiness in the eyes.

• Do Not Miss Diagnoses

  • Acute angle-closure glaucoma: Although rare, this condition is an emergency. It can cause severe eye pain, blurred vision, headache, nausea, and sometimes itchiness. It's crucial to diagnose and treat promptly to prevent permanent vision loss.
  • Herpes zoster ophthalmicus: Shingles that affect the eye can cause severe pain, itchiness, and potentially lead to serious complications like vision loss if not treated promptly.

• Rare Diagnoses

  • Atopic keratoconjunctivitis: A severe allergic eye disease that can cause intense itchiness, along with redness, swelling, and sometimes vision problems. It's more common in people with atopic diseases like eczema or asthma.
  • Vernal keratoconjunctivitis: A seasonal allergic condition that affects the eyes, causing itchiness, redness, and sometimes vision problems. It's more common in warm, dry climates and often affects young males.
  • Phlyctenular keratoconjunctivitis: An allergic type of conjunctivitis that can cause small, nodular lesions on the conjunctiva or cornea, leading to itchiness and redness. It's often associated with an allergic reaction to substances like staphylococcal toxins.