What characterizes allergic conjunctivitis?

Allergic conjunctivitis is primarily characterized by bilateral eye itching and redness. This condition typically results from exposure to allergens such as pollen, pet dander, or dust mites, leading to an inflammatory response in the conjunctiva. Itching and redness are hallmark symptoms, and patients often describe their eyes as feeling itchy, scratchy, or irritated. The bilateral nature of the symptoms is especially relevant; unlike some other types of conjunctivitis, such as bacterial or viral, which may present unilaterally, allergic conjunctivitis commonly affects both eyes simultaneously.

The presence of itching indicates the involvement of histamine and other inflammatory mediators released in response to allergens, differentiating it from other conjunctival conditions that do not typically induce these symptoms.