While most opticians have tools to measure your current prescription right from your current lenses, it is often frowned upon.
Most Opticians prefer you get a fresh eye exam and prescription, before spending the time and energy to make you new glasses. This is often because often vision degrades slightly over time and the old prescription is no longer accurate. Another reason is the current lenses have likely developed their own sratching or damage that lowers accuracy when determining your current magnification.
In short, your eye exam is often covered and is painless. Get your eyes tested before buying those stylish new glasses!
