Eyelashes are normally arranged in two or three rows on the upper and lower eyelids. They are more numerous on the upper eyelid, with approximately 150 eyelashes being present on the upper and 75 on the lower eyelid. Eyelashes, like body hair, are shed regularly every 100 to 150 days. Usually, the shed eyelashes do not cause any symptoms.

However, the cilia may sometimes get misplaced and end up in the lacrimal puncta, meibomian gland orifice, subconjunctival space, and corneal stroma. An eyelash that gets misplaced into the punctum has the potential to cause additional problems. Once the eyelash enters the punctum, the barbs on the hair prevent it from being expelled.