If you have a job that requires prism and there is enough power in the lens, it may be possible to create the prescribed prism by simply moving the lens off-center, rather than going through the trouble and expense of having the lab create it for you. Let's take a look at what is required and how you would calculate the necessary movement to fill a prescription for prism by decentration. Note: This video was edited from the original post to add some related information on aspheric lenses. | Lara