Eyelashes prevent most particles or objects from entering the eye, and tears usually are able to rinse out particles that do get in the eye. Occasionally, a solid object or projectile can adhere to the eye or embed itself below the surface of the eye.
Foreign bodies in the eye can be small specks of dirt or eyelashes, or larger objects such as cinders, rust or glass. The eye is damaged easily.
The most common type of eye injury is a corneal abrasion — a scratch in the cornea, the transparent layer that lies over your pupil (the center of your eye) and iris (the colored part). If the foreign body sticks to the undersurface of the eyelid, the scratch occurs when the object rubs against the cornea as you blink, and the scratch will be in a vertical line. Alternatively the foreign particle may be stuck to the clear cornea.
Small foreign bodies on the white of the eye actually often do not cause much discomfort.