Final answer:
Giant papillary conjunctivitis is an allergic conjunctivitis associated with contact lens irritation, differing from bacterial and viral types which involve pathogens. Bacterial keratitis is a risk for contact lens users and requires prompt treatment.
Step-by-step explanation:
Giant papillary conjunctivitis (GPC) is a type of allergic conjunctivitis which is commonly associated with contact lenses as the primary irritant, due to prolonged mechanical irritation. Unlike bacterial or viral conjunctivitis, which can be caused by bacteria such as Haemophilus influenzae or viruses like adenoviruses, GPC is a response to the chronic presence of a foreign body, namely contact lenses, which irritates the inner linings of the eyelids. The condition can result in discomfort, itching, and heavy discharge, and in such cases, discontinuation of contact lens use is recommended.
Infections like bacterial keratitis are also notable concerns for contact lens wearers, mostly caused by Staphylococcus epidermidis and Pseudomonas aeruginosa. Proper care and hygiene of contact lenses are crucial to prevent such infections, which can be severe and quickly lead to more serious conditions such as corneal scarring and blindness if left untreated.