What is the differential diagnosis (DDX) for persistent eye redness unresponsive to antihistamines and hydrating drops, with normotension (Normal Blood Pressure)?

Differential Diagnosis for Eye Redness

Single Most Likely Diagnosis

• Dry Eye Syndrome: This condition is a common cause of eye redness that may not respond to antihistamines or hydrating drops. It occurs when the eyes do not produce enough tears or the tears are of poor quality, leading to chronic irritation and redness.

Other Likely Diagnoses

• Blepharitis: A condition characterized by inflammation of the eyelids, which can cause eye redness, itching, and irritation. It may not respond to antihistamines or hydrating drops and requires specific treatment.
• Conjunctivitis (bacterial or viral): While antihistamines and hydrating drops may provide some relief, conjunctivitis often requires specific antimicrobial treatment. The lack of response to initial treatment suggests a possible infectious cause.
• Keratoconjunctivitis Sicca: An autoimmune condition that affects the eyes, causing dryness, redness, and irritation. It may not respond to standard treatments and requires specialized care.

Do Not Miss Diagnoses

• Acute Angle-Closure Glaucoma: A medical emergency that can cause eye redness, pain, and vision loss. It is essential to rule out this condition, as delayed treatment can lead to permanent vision loss.
• Endophthalmitis: A severe infection within the eye that can cause redness, pain, and vision loss. Prompt diagnosis and treatment are crucial to prevent serious complications.
• Scleritis: Inflammation of the sclera, which can cause severe eye pain, redness, and vision loss. It is essential to distinguish scleritis from other conditions, as it requires aggressive treatment to prevent complications.

Rare Diagnoses

• Sjögren's Syndrome: An autoimmune disorder that can cause dry eye syndrome, among other symptoms. While it is a rare condition, it should be considered in patients with persistent eye redness and dryness.
• Ocular Rosacea: A condition characterized by inflammation of the eyes and eyelids, often associated with rosacea of the skin. It can cause eye redness, irritation, and dryness, and may not respond to standard treatments.