Differential Diagnosis for Unilateral Eye Itching/Pain
Single Most Likely Diagnosis
- Dry Eye Syndrome: This condition is characterized by a lack of sufficient lubrication on the surface of the eye, leading to itching, pain, and sometimes a feeling of grittiness. The absence of drainage, discharge, erythema, and vision changes aligns with dry eye syndrome, making it a plausible first consideration.
Other Likely Diagnoses
- Blepharitis: An inflammation of the eyelids that can cause itching and pain without necessarily presenting with discharge or erythema, especially in its early or mild stages.
- Conjunctivitis (Allergic): Allergic conjunctivitis can present with itching and sometimes pain, but typically without significant discharge or vision changes. The absence of erythema does not rule out this condition, as it can be mild.
- Corneal Abrasion: A scratch on the cornea can cause pain and itching, and while it might not always present with discharge or erythema, it's a common enough condition to consider in the differential.
Do Not Miss Diagnoses
- Acute Angle-Closure Glaucoma: Although this condition typically presents with severe pain, blurred vision, and sometimes nausea and vomiting, it's crucial not to miss due to its potential for permanent vision loss. The absence of vision changes in the question does not entirely rule out this diagnosis, as presentations can vary.
- Herpes Zoster Ophthalmicus: This condition, caused by the reactivation of varicella-zoster virus in the ophthalmic division of the trigeminal nerve, can initially present with pain and itching before the onset of the characteristic rash. Missing this diagnosis could lead to serious complications, including vision loss.
Rare Diagnoses
- Sjögren's Syndrome: An autoimmune disorder that can cause dry eyes among other symptoms. While it's less common than dry eye syndrome, it's a consideration in patients with persistent symptoms.
- Trigeminal Neuralgia: A chronic pain condition that affects the trigeminal nerve, which could potentially cause eye pain. However, it's less directly associated with itching and is generally considered rare.
- Phlyctenular Keratoconjunctivitis: An inflammatory condition of the cornea and conjunctiva, often related to an allergic or immune response, which can cause itching and pain but is less common than other conditions listed here.