What is the most likely cause of pain during lens insertion, excessive tearing, and blurry vision with zigzag linear corneal staining?

The scenario described involves pain during lens insertion, excessive tearing, and blurry vision with zigzag linear corneal staining, which strongly suggests the presence of a foreign body under the lens. When a foreign object is trapped between the contact lens and the cornea, it can irritate the ocular surface, leading to discomfort or pain upon lens insertion. The excessive tearing is a response to the irritation caused by the foreign body, while the blurry vision can result from corneal distress and disruption in the optical surface due to the staining pattern.

The zigzag linear corneal staining seen under fluorescein dye indicates areas of epithelial damage, often associated with the friction caused by the foreign object. This combination of symptoms distinctly aligns with the presence of a foreign body rather than other potential issues related to lens fit or material interaction. Understanding this helps in diagnosing and addressing the underlying cause effectively, ensuring a better experience for the contact lens wearer.