Obtain your prescription
Have you had an eye test, but your optician didn't provide your prescription because they were concerned you wouldn't buy their glasses?
The UK Opticians Act of 1989 stipulates that it is the responsibility of every optician to provide you with your prescription. The optician will conduct a comprehensive eye examination and, as required by law, provide you with a copy of your personal prescription.
Understand your prescription
Important tip - The most common misunderstanding!
One of the most common mistakes customers make is selecting the wrong "+" and "-" when entering their prescription online. We cannot emphasize enough how important it is to pay extra attention when choosing these values!
At first glance (especially for new wearers), your eyeglass prescription may seem very confusing, but it is actually quite easy to understand. Your prescription usually looks like this (depending on the country):
Let's see what these measurements mean.
SPH / Sphere
The sphere value indicates the strength of the lens required to correct your focus. A positive number corrects hyperopia (farsightedness - difficulty seeing close objects), while a negative number corrects myopia (nearsightedness - difficulty seeing distant objects).
The sphere value is measured in diopters. Your prescription might also include terms like "plano" or an "infinity" symbol, which means you are neither nearsighted nor farsighted, and your sphere value is zero. However, you may still have astigmatism, which will be indicated by "CYL" (cylinder) and "AXIS" on your prescription. Typically, the range for sphere values is between 0.00 and +/- 20.00, in increments of 0.25.
CYL / Cylinder
CYL (Cylinder) and AXIS values compensate for astigmatism. So, what is astigmatism? Astigmatism occurs when the shape of the eye is slightly like an oval (similar to an American football or torus) rather than a perfect sphere like a soccer ball. This means the eye has difficulty focusing at certain angles.
This field can be left blank or filled with positive or negative values. The unit of measurement is diopters. Typically, the range for cylinder values is between +/- 0.25 and +/- 4.00, in increments of 0.25.
AXIS
Only when there is a value in the CYL field does the AXIS field come into play. The AXIS indicates the orientation of the astigmatism in your eye. The unit of measurement is degrees. Typically, the range for axis values is between 0 and 180, in increments of 1, 5, or 10 degrees. We only display integer values for the axis, but if your prescription includes a fractional degree, you can specify this additional condition when placing your order.
ADD / Addition
ADD stands for reading addition, which is the additional magnifying power needed for reading. This value is reflected in reading glasses, bifocal lenses, or progressive lenses.
The ADD value indicates how much additional power is required for near or intermediate vision on top of the distance prescription at the top of the lens. This extra value is always the same for both eyes and may appear only once on your prescription. However, it applies to both eyes. The unit of measurement is diopters, and the typical range is between +0.50 and +3.50, in increments of 0.25.
The ADD power only appears if your glasses are intended for reading or close-up work. If your glasses are for distance vision only, this will not be an issue. Some opticians use "Add" or "Near" to indicate the reading addition. Even if it appears only once on your prescription, it applies to both eyes and is consistent for both (e.g., 'Add' +2.50 - applies to both eyes).
Pupillary Distance (PD)
Pupillary distance is the distance between your pupils, ensuring that the prescription lenses are centered correctly in front of your eyes.
The most common method for measuring PD uses a simple PD ruler. Typically, the optician holds the PD ruler between their thumb and index finger, using the other three fingers to stabilize the patient's head. The optician then closes their right eye and instructs the patient to look at their open left eye, aligning the zero mark of the ruler with the patient's right iris edge. The optician then closes their left eye, opens their right eye, and instructs the patient to look at their open right eye. The value that aligns with the patient's left iris edge is the PD.
You can ask your optician for this measurement, or if you have an extra pair of glasses, you can send them to us along with your printed order. We can measure your PD from these to ensure the correct optical center for your lenses. We will return your new and old glasses to you.
For adults, PD usually ranges from 60 to 66mm (see diagram). While 63mm is a common PD, we recommend obtaining this measurement from your optician or an existing pair of frames. Alternatively, you can measure your own PD using the method described above.
If you prefer, you can also enter your monocular PD measurements in the additional information section when placing your order. This can be useful when purchasing progressive or bifocal lenses.
Measuring your PD with a single PD ruler
Typically, the optician holds the PD ruler between their thumb and index finger, using the other three fingers to stabilize the patient's head. The optician then closes their right eye and instructs the patient to look at their open left eye, aligning the millimeter mark with the center of the patient's right pupil. The optician then closes their left eye, opens their right eye, and instructs the patient to look at their open right eye, aligning the millimeter mark with the center of the patient's left pupil.
Add the two numbers to get your PD. For example, if your right eye is 32mm and your left eye is 33mm, your total PD is 65mm. For adults, PD typically ranges from 60 to 66mm.
If you prefer, you can also enter your monocular PD measurements in the additional information section when placing your order. This can be useful when purchasing progressive or bifocal lenses.
Refractive index and prescription range
We provide lenses with specific refractive indices to match different prescription ranges, ensuring the best visual performance:
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Prescription range 0 to -3.00: Lenses with a 1.6 refractive index. These lenses are lightweight and offer excellent visual clarity.
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Prescription range -3.01 to -6.00: Lenses with a 1.67 refractive index. These thinner lenses are designed for moderate prescriptions, providing greater comfort.
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Prescription range -6.01 and above: Lenses with a 1.74 refractive index. These ultra-thin lenses are ideal for higher prescriptions, ensuring the best aesthetics and comfort.