Allergic Conjunctivitis: This condition is characterized by itching, redness, and swelling of the eyes, often accompanied by clear discharge. It is a common and benign condition, usually triggered by allergens such as pollen, dust, or pet dander.

Vernal Keratoconjunctivitis (VKC): A seasonal allergic disorder that affects the eyes, causing itching, swelling, and clear discharge. It is more common in children and young adults.
Giant Papillary Conjunctivitis (GPC): An inflammatory condition that occurs in response to an allergic reaction or irritation, often associated with contact lens use. It presents with itching, swelling, and clear discharge.
Blepharitis: An inflammation of the eyelids that can cause itching, swelling, and clear discharge. It is often associated with meibomian gland dysfunction or rosacea.

Acute Angle-Closure Glaucoma (with atypical presentation): Although typically presents with severe eye pain, blurred vision, and redness, some cases may have a more subtle presentation, including itching and swelling. Missing this diagnosis can lead to permanent vision loss.
Keratoconjunctivitis Sicca (Dry Eye Syndrome): Can present with itching, swelling, and clear discharge, especially if the dryness is severe. It is essential to rule out this condition, as it can lead to complications such as corneal ulcers.

Phlyctenular Keratoconjunctivitis: A rare inflammatory condition that affects the eyes, often associated with an allergic reaction or infection. It presents with itching, swelling, and clear discharge, but is typically accompanied by a characteristic phlycten or nodule on the conjunctiva.
Mucous Membrane Pemphigoid: A rare autoimmune disorder that affects the mucous membranes, including the eyes. It can cause itching, swelling, and clear discharge, but is often accompanied by other systemic symptoms.