Low-velocity projectiles, such as windblown dust particles, can be retained in the tear film, the upper tarsal plate, or in a conjunctival sac. The patient will feel a foreign-body sensation but may not be very accurate in locating the foreign body by sensation alone. On examination, normally occurring white papules inside the lids can be mistaken for foreign bodies, and transparent foreign bodies can be invisible in the tear film (until outlined by fluorescein dye) after orbit radiographs are obtained.