In average "blink of an eye" lasts only a tenth of a second, but that's all the time needed to clear away dust particles and spread lubricating fluids across the eyeball. Every time you blink, your eyelids spread a cocktail of oils and mucous secretions across the surface of the eye to keep your globes from drying out. Blinking also keeps eyes safe from potentially damaging stimuli, such as bright lights and foreign bodies like dust.
Blinking is controlled by a reflex, an automatic nerve action. Besides making your eyes blink regularly, the automatic control also works to close your eyelids when something is about to strike your face. So blinking is important in protecting your eyes.