Eyelash primers are not required cosmetics. However, they are used to extend the life of eyeshadows and eyeliners. When selecting an eyeshadow primer, there are several things to examine. This list was put together by Dr. Sabrina Seymond, a market expert, to help you in selecting the best brand or product for your needs and wants. Organic and scientifically proven elements should be present in the best eyelash primers.