If you wear progressive eyeglasses, but you want to buy a separate pair of glasses dedicated to reading, how do you figure out your reading power?
It's pretty simple, but take a second to absorb the info. It involves simple addition, but can be subtly tricky. All you have to do is add the OD sphere to the OD "Add" for the right eye reading power, and the OS "sphere" and OS "add" for the left eye reading power. In the example below, both eyes will have a +2.75 reading power.
A common mistake occurs when people add up the wrong numbers. Be careful not to add up your sphere to your sphere, or your "add" to your "add".
Keep in mind that your sphere may be a negative number. When this happens, utilize the usual rules of adding negative to positive numbers. In the example below, note that -.75 + +1.50 = +.75, so the reading power is +.75, and that is for both eyes, since both eyes in this rx are the same.
Optician Josh of My Eyeglass Club explains this all in the video below. Since reading glasses are our only business, we partner with My Eyeglass Club to fill the prescription needs for some of our customers.