SUNBOND OPTIX / LENS TESTING The first batch passing tells you the formula works. It does not tell you the hundredth batch will. A photochromic lens is not a coating with a colour in it. It is a chemical system that has to take in UV, change state, and come all the way back, tens of thousands of times. How well it does that is decided during manufacture. Dye concentration. Imbibing time and oven temperature. Resin lot. Cure schedule. Coating thickness. Every one of those move