 Oxygen permeability continues to be an extremely important factor in the development of these devices and is one of the main reason that much research is beginning to focus on this area of drug delivery.The amount of water content that a particular contact lens can retain is another extremely important factor that must be taken into account when these devices are designed.Research in this specific area of design suggests that contact lens wearers find it more comfortable to wear lenses that retain water more than those that deter water.