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Reading Prescriptions
How to read your prescription for glasses or lenses
On your prescription, you’ll see all kinds of parameters and values. To break it down for you, we have created a quick overview of all the parameters and their common abbreviations for both glasses and contact lenses.
Please remember that you should renew your prescription at least once a year. Even if you haven’t noticed any changes in your vision, it’s important to be examined by your optician. Under UK law, it is the buyer’s responsibility to maintain an up-to-date prescription before purchasing online.
you’re looking to order contact lenses and need help reading your prescription? It might not be easy interpreting what’s written there, so we’ve put together a small guide to help you. We’ve also included some common questions regarding prescriptions for glasses or lenses. Take a look below and don’t hesitate to contact us in case you have any further questions.
| Abbreviation | Explanation |
| SP(H), PWR or D | Sphere, Power, or Dioptre value indicates the value of near or farsightedness (+ or -). A possible (=) sign indicates (-). |
| CYL or CP | Cylinder indicates astigmatism and tells the vertical curve of your eyeball |
| X, AX, AXE | Axis indicates the degree and direction of the cylinder |
| ADD | ADD power indicates the extra strength for multifocal lenses |
| D and N | For your ADD power, these letters simply differentiate between you dominant (D) and non- dominant (N) eye |
| BC | Base Curve is used specifically for lenses and indicates the degree of curvature and how the lens will fit on the eyeball |
| DIA | Diameter is used specifically for lenses and describes the width of the lens |
| PL | Plano indicates coloured contact lenses without power |
| EXP | Expiration date indicates when the lenses will expire |
| PD | Pupillary distance is a value used specifically for glasses and indicates the distance between your pupils. The exact distance is important in order for us to correctly centre your lenses on your eyes. |
Plus or Minus?
Are you shortsighted (myopic), meaning you can’t see well in the distance? Then your power will be minus. Farsighted, or struggling to see close objects? This condition is also called hyperopia, and it means your power will be plus. This value can be indicated on your prescription as either “D” diopter value; “PWR” power; or “SPH” sphere. Be careful when selecting your power, as a small slip-up can cause a big difference in eyesight. For lenses, if you have accidentally ordered the wrong value, you can always return unopened boxes according to our Exchange & Return Policy.
How do I choose cylinder and axis?
Cylinder and axis are two measurements in toric lenses necessary to correct astigmatism. The cylinder is an extra correction that denotes the severity of astigmatism and has a minus value expressed in increments of 0.25. The axis is expressed in degrees between 0° and 180°. We advise you to consult with your optician if you have any doubts regarding these two parameters.
What does the ADD power mean?
If you suffer from presbyopia and require multifocal contacts, your prescription may include an ADD, or additional power to help with near vision. ADD powers range from +0.50 to +3.00. Some brands of lenses offer ADD power in low, medium or high values. “D” and “N” may further indicate which eye is the dominant eye (D) and which is non dominant (N). Some manufacturers of lenses require you to properly select this as well. In case you have any doubts about this, consult us or your optician first.
Right or Left Eye?
Your optician may indicate this with a simple “L” and “R” or the Latin terms “Oculus Dexter” (right) and “Oculus Sinister” (left). When ordering glasses, simply input the correct values for your left and right eye. In case you’re ordering lenses, if you require a different power for each eye, you’ll need to click “Select attributes for second” eye when placing your order on our website. When placing your order, there is no distinction between left and right, so just think of them as Eye #1 and Eye #2 (be sure to make sure whichever values input correspond to the correct eye). If you have the same prescription for both eyes, there’s no need to select the second attribute! Just fill in your parameters once, and select the number of boxes you require.