The Photomatic lens darkens to the color of sunglasses when exposed to sunlight or UV, and returns to its clear state when indoors, away from UV light. The Photomatic lens is made of a variety of materials, including plastic and mineral glass. It is commonly used as sun protection by simply dimming from a clear lens indoors to a deep sunglass tone when outdoors, and vice versa. It usually takes about 30 seconds for it to go completely dark and between five and ten minutes for it to return to its clear state. Photomatic lens anti-reflective coating further improves performance. An anti-reflective coating allows more light to pass through the Photomatic lens for sharper vision in low-light conditions (such as driving at night) and eliminates reflections from sunlight and other light sources on the inside of the lens. In addition to protecting your eyes from outdoor reflection, Photomatic also offers an additional important benefit – with the added Remuve 420 finish, it helps protect your eyes from harmful blue light. Blue light contributes to constant eye strain and causes stress in the retina. It's even possible that long-term exposure to harmful blue sunlight or computer screens, smartphones, and other digital devices can increase the risk of macular degeneration and other eye problems later in life.