Hypopigmentation is the loss of skin color. It is caused by melanocyte or melanin depletion, or a decrease in the amino acid tyrosine , which is used by melanocytes to make melanin.  As melanin pigments tend to be in the skin, eye, and hair, these are the commonly affected areas in those with hypopigmentation. 
Hypopigmentation is the absence of normal amounts of melanin (the chemical that gives skin its color) caused by disease, injury, burns or other trauma to the skin. Hypopigmentation can be tricky to treat. There are topical medications that sometimes help, and light-based procedures like IPL, excimer lasers, and the Fraxel Restore laser can also be used.