Over the past five years, this column has covered many topics related to lenses and prisms, but it has not yet discussed yoked prisms in detail. As we all learned in optometry school, a prism shifts light, and the person shifts their eye in response. Specifically, yoked prisms shift images the same direction and amount in both eyes. If you stick with the basic understanding of prisms as chiefly ray shifters (1.00cm for every 1.00m traveled per 1.00D of prism), you will miss their true power. Read More