This chapter introduces contact lenses as a medical device designed to improve vision. The introduction to contact lenses, which include hard and soft contact lenses and the alternative purpose of wearing contact lenses, such as for cosmetics, were mentioned in this chapter. Then, this chapter is followed by the evolutionary path of contact lenses, which covers the history of contact lenses from the earlier theory by Leonardo Da Vinci, the birth of scleral lenses and plastic contact lenses, soft lenses from silicone material and its improvement, advancement and current technology of contact lenses. Furthermore, this chapter discusses the forecast and projected demand for contact lenses, which covers the compound annual growth rate (CAGR) from 2023 to 2030, factors that increase the global demand for contact lenses, efforts in pushing technological advancements, lists of the current key players in contact lens market, reasons of wearing contact lenses, and the regional distribution of contact lens revenue. Lastly, this chapter discussed how contact lenses improve vision by correcting common eye problems such as near-sighted and far-sighted vision.