Tear Film Break-Up

As part of our eyes' normal function, tear film is produced, spread over the eyeball, and continually washed out through tiny holes on the edges of the upper and lower eyelids. Our impulse to blink is due to the tear film thinning out and evaporating, giving us the automatic impulse to blink and refresh the tear film. The process of the tear film thinning out is called tear film break-up.

When not enough tear film is being produced to keep the eye moist between blinks, or when the tear film composition is abnormal, tear film break-up can occur too quickly—before our impulse to blink. This causes dry spots to appear on the eye's surface (cornea).

Even if tear film is fairly normal, dry spots can still appear if the cornea has been compromised in some way. The cells on the corneal surface have very delicate structures that allow the tear film to stick to the eye, and if compromised, tear film can break-up too quickly.