There are many different types of sight systems that are available for use on defensive handguns. While some sight systems are manufactured with materials that are not practical for rigorous use and combat applications, others are designed in a way that can impede the shooter from obtaining a fast sight picture. Sight systems that don’t conform to the physiology of how the human eye functions in combat can actually hinder or delay the shooter from finding the front sight under duress and lead to loss of combat accuracy. This article will explore handgun sight design and provide technical information on how to select a sight system that will work best for your personal defense handgun. There are five primary elements that affect how we see and use handgun sights during combat: vision, sight design, lighting, movement and applications.