Differential Diagnosis for Unilateral Eye Redness with Photophobia and Mild Headache
- Single most likely diagnosis:
- Conjunctivitis: This is the most common cause of unilateral eye redness, often accompanied by photophobia and mild headache. The 4-day duration suggests an infectious or allergic etiology.
- Other Likely diagnoses:
- Uveitis: Inflammation of the uvea can cause eye redness, photophobia, and headache. It can be unilateral and may have a sudden onset.
- Corneal abrasion or ulcer: Damage to the cornea can lead to redness, photophobia, and pain, which might be perceived as a mild headache.
- Acute angle-closure glaucoma (partial): While typically more severe, a partial or early presentation could manifest with unilateral redness, photophobia, and mild headache.
- Do Not Miss diagnoses:
- Acute angle-closure glaucoma (full): A medical emergency that requires immediate attention. Symptoms can include severe eye pain, redness, photophobia, and headache, but early or partial presentations might be less severe.
- Endophthalmitis: A severe infection within the eye that can follow surgery or trauma. It presents with severe pain, redness, and vision loss, but early stages might be less dramatic.
- Orbital cellulitis: An infection of the tissues surrounding the eye, which can cause redness, swelling, pain, and photophobia. It can lead to serious complications if not treated promptly.
- Rare diagnoses:
- Scleritis: Inflammation of the sclera, which can cause severe pain, redness, and photophobia. It is less common than other causes of red eye but should be considered in the differential.
- Keratitis: Inflammation of the cornea, which can be caused by infection or injury. It can present with pain, redness, and photophobia.
- Optic neuritis: Inflammation of the optic nerve, which can cause vision loss, pain with eye movement, and might be accompanied by headache and photophobia, though typically not with significant redness.