Which type of allergic conjunctivitis is characterized by a bilateral presentation?

Perennial allergic conjunctivitis is characterized by its bilateral presentation due to the continuous exposure to allergens that can occur throughout the year. This persistent form of allergic conjunctivitis is typically triggered by indoor allergens such as dust mites, pet dander, and mold, leading to symptoms that affect both eyes simultaneously.

Other types of allergic conjunctivitis, while they may also present bilaterally, have distinct characteristics. For example, vernal keratoconjunctivitis and giant papillary conjunctivitis tend to be associated with specific environmental triggers and typically manifest in specific populations (such as children and contact lens wearers, respectively). Seasonal allergic conjunctivitis is primarily linked to outdoor allergens and tends to have a seasonal pattern, which can also result in bilateral symptoms but isn’t defined as a true year-round allergy like perennial allergic conjunctivitis. Hence, the defining feature of perennial allergic conjunctivitis is its year-long presence and bilateral impact.