Axon Optics SpectraShield Lenses are personalized digitally surfaced lenses. This means we can make a lens personalized to your prescription and frame. If you have a simple single vision correction with astigmatism (sph, cyl and axis), prism or have a correction stronger than +/-1.50 we will also need the Pupillary Distance (PD) and Ocular Center (OC) for your selected frame. These measurements are obtained with the frame on your face. If your provider does not sell frames or will not give you the complete prescription, you can do it yourself or with the help of a friend.
The Ocular Center (OC) is the vertical measurement in millimeters from the bottom of the lens in your frames, to the beginning of the progressive addition on a progressive lens, or the top line of a lined bifocal. The determined OC is unique to each specific frame and is measured while the frame is on your face after adjustment. Even if you have multiple frames that are the same, the OC will need to be measured for each frame.
When these measurements are not available or provided in an order, our technicians can calculate the center based on your frame dimensions and prescription type. Multi-focal lenses can sometimes take up to 2 weeks to get used to them, especially if you are new to progressives. Sometimes there is a little visual disturbance or disorientation, but it usually subsides within these 2 weeks. It is helpful if you do not switch back and forth between another frame.
If you place transparent scotch tape vertically on the lens, you can then mark your pupils with a sharpie. The mm measurement between the dots is the PD. The mm measurement from the dot to the bottom of the frame is the OC. You can also leave the tape/markings on the lenses so my technician can confirm the measurement. Here is an image submitted by another customer.
How do I measure my own OC?
1. Use a ruler that has millimeter measurements. You can also use a ruler with centimeter measurements and simply times the result by 10 to get your millimeter measurement.
2. Put the glasses on your face and adjust them so that they sit comfortably.
3. Stand about 8 inches (20 cm) away from a well-lit mirror with your face parallel and square to the mirror.
4. Align the ruler's zero (0) measurement to the lowest point at the bottom of your lens (not the bottom of the frame), keeping it exactly vertical.
5. Stare straight ahead and read the millimeter line that lines with the center of your pupil. This is your segment height measurement for these frames.
6. Repeat these steps at least 3 to 5 times to get an accurate and consistent measurement. Make sure your head and the ruler do not move after lining up the zero (0) measurement with the bottom of your lens until you note your measurement. Ask a friend to help if you are having trouble.
Pupillary distance (PD) measures the distance between the centers of your pupils. This measurement helps us determine the “sweet spot” on your optical lenses. The average adult’s PD is between 54-74 mm. Your eye doctor will usually measure your PD during an eye exam and usually has it on file even if it is not on your paper prescription. If you cannot obtain your PD, you can measure it yourself or with the help of a friend.
How to Measure Your PD?
1. As before, stand 8 inches away from a mirror.
2. Hold the ruler against your brow.
3. Close your right eye then align the ruler’s 0 mm with the center of your left pupil.
4. Look straight then close your left eye and open your right eye.
5. The mm line that lines up to the center of your right pupil is your PD.
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