Allergic Conjunctivitis: This condition is characterized by inflammation of the conjunctiva due to an allergic reaction, leading to symptoms such as redness, itching, and swelling. The patient's lack of response to antihistamines like Allegra and Zyrtec, and eye drops, might suggest a more severe or chronic form, but it remains a primary consideration given the symptom profile.

Blepharitis: An inflammation of the eyelids that can cause redness, itching, and swelling. It's often associated with other conditions like rosacea or seborrheic dermatitis and might not fully respond to typical allergy treatments.
Dry Eye Syndrome: Can cause irritation, redness, and a sensation of itchiness, especially if the patient has been using eye drops that are not adequately addressing the underlying issue or if the drops themselves are irritating.
Contact Dermatitis: An allergic reaction or irritation from substances like makeup, contact lens solution, or other products coming into contact with the eyes or eyelids, leading to redness, swelling, and itching.

Acute Angle-Closure Glaucoma: Although less common, this is a medical emergency that can present with redness, swelling, and pain in the eye, along with vision disturbances. It's crucial to rule out this condition due to its potential for permanent vision loss if not promptly treated.
Orbital Cellulitis: An infection of the tissues surrounding the eye, which can cause swelling, redness, and pain. It's a serious condition that requires immediate medical attention to prevent complications like vision loss or spread of infection.
Keratoconjunctivitis Sicca (Severe Dry Eye): In severe cases, can lead to significant discomfort and might not respond well to standard treatments, necessitating more aggressive management to prevent complications.

Giant Papillary Conjunctivitis: Typically associated with contact lens use, this condition can cause itching, redness, and discomfort due to the formation of large papillae on the underside of the eyelid.
Vernal Keratoconjunctivitis: A severe allergic eye condition more common in children and young adults, characterized by intense itching, photophobia, and stringy discharge, which can lead to corneal complications if not properly managed.
Ocular Rosacea: A condition where rosacea affects the eyes, leading to symptoms like redness, itching, and burning sensations, which might not respond to typical allergy treatments and requires management of the underlying rosacea.