How to Find the Right Lens for Computer or Reading Glasses
What is this? This simple calculator converts your current prescription for eyeglasses into a prescription for single-vision glasses that focus at a specific distance. This information is useful when choosing eyeglasses for reading or for working at a computer screen - or for anything else you want to see at a fixed distance.
What do I need?
You need to know the distance from your eyes to what you want to focus on. You may want to ask someone to help you measure this distance.
You also need a current prescription for eyeglasses. You need only the SPH (sphere) portion of your prescription. The cylinder and axis portions remain the same. Ignore the ADD since that is for bifocals.
If you do not need prescription glasses but still would like glasses for close distances, use 0 for the SPH.
Then fill out the form below and press the button to find your new lenses.
What next? Use the results from this calculator for the SPH value for your new glasses. Or, if your eyes are not too different from each other, you may want to try a pair of inexpensive glasses with the magnification shown for the non-prescription lenses. The example below shows how a current prescription is converted to a new prescription for single-vision glasses that will focus at a distance of 12 inches (30.5 cm).
Approximate non-prescription lenses: +2.25
For the example above, first you could try non-prescription glasses with a magnification of around +2.25. You may find that a little more or less magnification works better for you so don't be afraid to try some other values around +2.25. If you do not like the non-prescription glasses, you could purchase a pair of single-vision prescription glasses using the values shown for the new lenses. In this example, you would use +2.75 for the left eye, +1.50 for the right eye, and the same cylinder and axis values as the original prescription.
Where to buy new glasses? Inexpensive non-prescription glasses are widely available at drugstores, bargain stores, and big-box retailers. Prescription glasses can be purchased online from various companies. Some example retailers are shown below.
How does this work? An eyeglass prescription is for a lens that corrects your vision to see clearly at a long distance. By putting another lens in front of your eyeglass lens, the resulting focal point can be changed to any desired closer distance. The power of the additional lens is computed as 1 divided by the desired focal distance measured in meters. This calculation gives the lens power measured in diopters. Instead of putting an extra lens in front of your eyeglass lens, though, we can simply add the power of the new lens to the power shown in the sphere value in your current prescription. The result is a new single-vision lens that focuses at the desired distance.
Notice: The information provided in this website is for educational purposes only. No guarantees are made that the information is completely correct or that anything you do with this information will meet your specific needs. This is not medical advice. You should see an appropriate medical provider for all questions concerning your health.
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