Before revision: The Phoroptor was smaller (lenses reduced again, to 9/16 inch diameter) and more precisely made than the 574, but with a similar power range, and the front clips for hand-held trial lenses were removed and replaced with batteries of cylinder lenses ranging from -0.25 to -4.75 .
After revision: The Phoroptor was smaller (lenses reduced again, to 9/16 inch diameter) , with a similar power range, and the front clips for hand-held trial lenses were removed and replaced with batteries of cylinder lenses ranging from 0.25 D to 4.75 D .