If you have already got your eyeglasses prescription, you need to split the Add number in half, and combine that split number with the SPH to get a single vision lenses for computer use. For example, a typical prescription would look like this:
OD: -1.50 -0.25 x 165
OS: -1.00 DS
ADD: + 2.00 OU
PD 64/62
If you would like to buy a pair of single vision computer glasses, you will have to split the Add number in half, and combine that split number with the SPH, Ignore the remaining Add and use the bigger PD 64mm. Here is the standard format:
SPH CYL AXIS
OD: -0.50 -0.25 165
OS: Plano DS
PD 64mm
Hope this helpful.