What symptom is most likely caused by a damaged contact lens?

The most relevant symptom linked to a damaged contact lens is sudden onset pain. When a contact lens is damaged, it can cause discomfort and pain to the eye due to sharp edges, tears, or debris that may scratch or irritate the cornea. This immediate and intense pain is a clear indication that the lens is no longer functioning properly and may be causing harm to the ocular surface, prompting the need for removal and further evaluation.

Other symptoms like itching and redness may occur due to various conditions such as allergies or dry eyes, and persistent blur could indicate an incorrect lens fit or other refractive issues rather than a specific issue with the lens itself. Increased tear production often arises as a response to irritation or dryness but does not specifically point to a lens being damaged. Thus, sudden onset pain directly signifies that the contact lens may be problematic, making it the most appropriate symptom to identify a damaged lens.