# Adapting a eyeglass prescription **URL:** \ **Category:** In My Humble Opinion\ **Created:** [July 17, 2014, 12:58am UTC](https://boards.straightdope.com/t/adapting-a-eyeglass-prescription/693322 "2014-07-17T00:58:22Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![shortwizard](https://avatars.discourse-cdn.com/v4/letter/s/71c47a/32.png) [@shortwizard](https://boards.straightdope.com/u/shortwizard)\ **Post date:** [July 17, 2014, 12:58am UTC](https://boards.straightdope.com/t/adapting-a-eyeglass-prescription/693322/1 "2014-07-17T00:58:22Z")
I have a prescription for progressive lenses, which I have and hate, and he also wrote a prescription for computer glasses because I am in front of my monitor4-5 hours a day. My question is this - does anyone know how to adapt the prescription for computer glasses with bifocals for reading or will I have to go back to the eye doctor for that? I am taking the progressives back and I would rather order the bifocals online and a fraction of the cost. I may get a pair for distance to keep in the car for driving, but I can see pretty well without them, except at night. I do a lot of computer work, reading, and crafting and these progressives are terrible. ---
**Author:** ![Kent\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kent_clark/32/105_2.png) [@Kent\_Clark](https://boards.straightdope.com/u/Kent_Clark)\ **Post date:** [July 17, 2014, 1:32am UTC](https://boards.straightdope.com/t/adapting-a-eyeglass-prescription/693322/2 "2014-07-17T01:32:20Z")
Looking at my prescription, I see values for O.D., O.S., Add O. D. and Add O.S. The O.D. (right eye) and O.S. (left eye) have additional values marked CYL and AXIS. Those are the measurements for distance. The ADD values are corrections to the distance for near or reading focus. Look at the prescriptions for both your regular and your computer glasses. You’ll notice the regular Rx O.D. and O.S. values will start with some number like -3.00. Look at your computer prescription and you’ll see the numbers will be some lesser number, like -2.00. Your computer bifocals will use the numbers from your computer Rx and the ADD numbers from your progressive Rx. ---
**Author:** ![shortwizard](https://avatars.discourse-cdn.com/v4/letter/s/71c47a/32.png) [@shortwizard](https://boards.straightdope.com/u/shortwizard)\ **Post date:** [July 17, 2014, 1:48am UTC](https://boards.straightdope.com/t/adapting-a-eyeglass-prescription/693322/3 "2014-07-17T01:48:36Z")
Do I still need the axis numbers? They are on the computer glasses prescription. ---
**Author:** ![shortwizard](https://avatars.discourse-cdn.com/v4/letter/s/71c47a/32.png) [@shortwizard](https://boards.straightdope.com/u/shortwizard)\ **Post date:** [July 17, 2014, 1:50am UTC](https://boards.straightdope.com/t/adapting-a-eyeglass-prescription/693322/4 "2014-07-17T01:50:02Z")
And they have a cylinder on there, too. ---
**Author:** ![shortwizard](https://avatars.discourse-cdn.com/v4/letter/s/71c47a/32.png) [@shortwizard](https://boards.straightdope.com/u/shortwizard)\ **Post date:** [July 17, 2014, 1:53am UTC](https://boards.straightdope.com/t/adapting-a-eyeglass-prescription/693322/5 "2014-07-17T01:53:08Z")
Also, I am looking at a 2 year old prescription and the axis on the OD only was o40, with none on the OS and now it’s 065 on the OD and 118 on the OS - isn’t that a lot of change in just 2 years? ---
**Author:** ![Kent\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kent_clark/32/105_2.png) [@Kent\_Clark](https://boards.straightdope.com/u/Kent_Clark)\ **Post date:** [July 17, 2014, 2:26am UTC](https://boards.straightdope.com/t/adapting-a-eyeglass-prescription/693322/6 "2014-07-17T02:26:33Z")
Yes, that’s a lot of change and a pretty good indicator that you shouldn’t be using a 2-year old prescription for anything. Either one of the scrips is wrong or your eyes are changing rapidly. I know you want to cheap out on this, but I think you should go to an optometrist, get your eyes professionally checked, and ask for distance, computer and near prescriptions. Then you can go online and order whatever you need. And yes, you’ll need CYL and AXIS numbers. They’re the same for near and distance settings, that’s why they’re only listed once. ---
**Author:** ![shortwizard](https://avatars.discourse-cdn.com/v4/letter/s/71c47a/32.png) [@shortwizard](https://boards.straightdope.com/u/shortwizard)\ **Post date:** [July 17, 2014, 2:54am UTC](https://boards.straightdope.com/t/adapting-a-eyeglass-prescription/693322/7 "2014-07-17T02:54:17Z")
I did go to an optometrist and the new prescription is only a week old. I just can’t understand why such a big change in the cylinder and axis when there is only a little change in the sphere on my left eye. I guess I will have to ask about that when I take these miserable glasses back. The distance part of them seem awfully strong when I look through, even though things are in focus, it feels like my eyes are working harder. And when I take them off everything is blurrier than it was before I wore them. How can that be good? ---
**Author:** ![Ferret\_Herder](https://avatars.discourse-cdn.com/v4/letter/f/e47774/32.png) [@Ferret\_Herder](https://boards.straightdope.com/u/Ferret_Herder)\ **Post date:** [July 17, 2014, 2:58am UTC](https://boards.straightdope.com/t/adapting-a-eyeglass-prescription/693322/8 "2014-07-17T02:58:35Z")
Cylinder and axis relate to astigmatism. Axis is just (basically) where your cornea and/or lens is misshapen, while cylinder is how much. I would not say that was a big change in two years to have that happen to axis. It only shifted 20 degrees in your right eye, and you developed astigmatism in your left eye, from none previously. ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [July 17, 2014, 3:03am UTC](https://boards.straightdope.com/t/adapting-a-eyeglass-prescription/693322/9 "2014-07-17T03:03:21Z")
Paging DougK.