Differential Diagnosis for Unilateral Pink Eye
Single Most Likely Diagnosis
- Viral conjunctivitis: This is the most common cause of unilateral pink eye, characterized by watery discharge and the absence of itching. It is highly contagious and often accompanied by a viral upper respiratory infection.
Other Likely Diagnoses
- Bacterial conjunctivitis: Although it typically presents with a thicker, more purulent discharge, some bacterial conjunctivitis cases can have a watery discharge, especially in the early stages.
- Allergic conjunctivitis: While allergic conjunctivitis is usually itchy and bilateral, some cases can be unilateral and less itchy, especially if the allergen exposure is asymmetric.
- Irritant conjunctivitis: Exposure to a chemical irritant or a foreign body in the eye can cause unilateral pink eye with watery discharge.
Do Not Miss Diagnoses
- Acute angle-closure glaucoma: Although rare, this condition is an emergency that can present with unilateral redness, watery discharge, and severe eye pain. It requires immediate medical attention to prevent vision loss.
- Herpes simplex keratitis: This viral infection can cause unilateral pink eye, and if left untreated, can lead to serious complications, including vision loss.
- Corneal ulcer: A bacterial or fungal infection of the cornea can present with unilateral redness, watery discharge, and severe eye pain, requiring prompt medical attention to prevent vision loss.
Rare Diagnoses
- Sjögren's syndrome: An autoimmune disorder that can cause unilateral or bilateral dry eye, but in some cases, can present with watery discharge due to inflammation.
- Sarcoidosis: A systemic disease that can cause uveitis, which may present with unilateral pink eye and watery discharge.
- Tuberculosis: Rarely, tuberculosis can cause conjunctivitis, which may present with unilateral pink eye and watery discharge.