Very nice article on UXmatters by Pabini Gabriel-Petit. Part IV in her series on “Color Theory for Digital Displays” she describes how color can be used to ensure web sites and applications are accessible to people with color-deficient vision.

If you do not consider the needs of people with color-deficient vision when choosing color schemes for applications and Web pages, those you create may be difficult to use or even indecipherable for about one in twelve users.