When and why you advice with progressive lenses ? and what is the corridor ? , and what is the proper height for corridor 14 ?

progressive lenses have many details that can effect positively in case you collect the correct informations from the customer specially his age , eye test , high addition or not , so you can choose the proper corridor , so the customer can adapt faster with his eyeglasses .

that is in addition to the frame details , so bigger or smaller lenses can effect in the distortion that may the customer will see on the lenses aspects .