Simple and toric transposition

The document explains transposition, a method for creating equivalent prescriptions in glasses, especially for correcting refractive errors with opposing cylinder powers in each eye. It details two types: simple and toric transposition, outlining various formulas and examples for calculating new spherical and cylindrical power, along with their axes. It also emphasizes the need for the cylinder's sign to match the base curve during toric transposition and presents specific calculation steps for deriving final prescriptions.