what does dia mean in contact prescription
Here are the definitions of the symbols/abbreviations used in a typical contact lens prescription: 1  Eye - Which eyes the prescription line item is for. 2  SPH - Sphere (this can also be referred to as Power or PWR) 3  BC - Base Curve (usually a number between 8 and 10)  DIA - Diameter (usually a number between 13 and 15)