A glasses prescription looks like a code, but once you know what each part means, it is simple to read. This guide explains every number on your prescription, so you can understand it and order glasses online with confidence.
The layout of a prescription
A prescription is a small table with one row for each eye and columns for the different values:
- OD (oculus dexter) — your right eye.
- OS (oculus sinister) — your left eye.
- SPH (sphere), CYL (cylinder), AXIS, ADD — the lens powers.
- PD (pupillary distance) — the distance between your pupils, in millimetres.
SPH — the main power
SPH is the main lens power for each eye. A minus sign (−) means short-sightedness (myopia): you see near things clearly but distance is blurry. A plus sign (+) means long-sightedness (hyperopia): distance is clearer than near vision. A value of 0.00, sometimes written as PLANO or PL, means no power is needed for that eye. The bigger the number, the stronger the prescription — for example, −4.00 is stronger than −1.00. SPH is usually written in steps of 0.25.
CYL and AXIS — astigmatism
CYL corrects astigmatism, which happens when the eye is shaped slightly more like a rugby ball than a football, so light focuses unevenly. CYL is the extra power needed, and AXIS is its direction, given as a number from 0 to 180 degrees. If CYL and AXIS are blank or marked with a dash, you do not have astigmatism correction in your prescription.
ADD — reading addition
ADD is the extra power added for reading, used in bifocal or varifocal (progressive) lenses. It is usually between +0.75 and +3.00. If you only need glasses for distance, ADD is usually blank.
PD — pupillary distance
PD is the distance between the centres of your pupils, in millimetres — for example, 62, or written as two numbers such as 31/31 (one for each eye). The PD centres the lens correctly in front of each eye. It is not always printed on the prescription; if yours does not include it, an optician can measure it for you.
Prism and Base
Some prescriptions include prism values, written as a number with a direction such as Base In, Base Out, Base Up or Base Down. Prism corrects eye alignment problems. It is less common and is usually prescribed by an eye specialist, so most prescriptions will not have it.
What else is on the prescription
- Expiry date: prescriptions usually last one to two years. An old prescription may no longer match your eyes.
- Date of examination and prescriber: who tested your eyes and when.
- Distance or near: some prescriptions show separate values for distance and reading.
How to order glasses online with your prescription
- Enter the SPH, CYL, AXIS, ADD and PD exactly as written, for each eye.
- Double-check the minus and plus signs — a wrong sign gives the wrong lens.
- If a value is blank, enter 0.00.
- Check that the prescription is still in date.
If you are unsure about any value, message us on WhatsApp at +92 328 9695238 or send a consultation enquiry before ordering.
Keep your prescription current
Eyes change over time, so have them tested every one to two years — and more often for children, whose eyes change faster. A current prescription means sharper vision and less eye strain. Our free online eye test is a basic screening only; it cannot replace a full eye examination.
Ready to order? Browse prescription eyeglasses at Frame Aura.
An example prescription
Here is what a typical prescription might look like: right eye (OD) SPH −2.00, CYL −0.50, AXIS 90; left eye (OS) SPH −1.75, CYL −0.25, AXIS 80; ADD +1.00; PD 62. This means both eyes are short-sighted, with a small amount of astigmatism in each, and a reading addition of +1.00. If your prescription looks confusing, compare it with this example — the layout is the same on most prescriptions issued in Pakistan.