Lid stones are caused by repeated chronic inflammation of the conjunctiva, which causes a large number of epithelial cells to be shed, which accumulate and concentrate with the mucus in the eye to form stones. Conjunctival stones appear as single or multiple hard yellowish-white dots on the lid conjunctiva. When the conjunctival stones protrude from the conjunctival surface, they irritate the cornea, creating a foreign body sensation, or abrasion, and even causing corneal abrasions and erosions, which need to be removed with a sharp knife or foreign body needle under surface anesthetic.