PD for online eyeglasses shopping
PD or Pupilary Distance is the exact measurement in millimeteres from the center of one pupil to the center of the other while your eyes are looking perfectly straight. It is one of the most important values used by your optician to create eyeglasses that will fit you perfectly. The reason PD is so important is due to the nature of the lens in your eyeglasses and the way they sit within the frame. By knowing the PD, the optician will know where the center of the lens should be located and where the bend in the lens will exist.
The PD is usually given on the prescription from your eyecare professional. More and more doctors and stores will refuse to give you your PD to stop you from ordering glasses from an online discount store and force you to buy from them at full retail price. Please be aware that this is illegal in most states and you can demand your PD at any time. However, if you don’t want to deal with the whole process you can simply take a ruler and measure the PD yourself. Place the ruler flat on your fore head, and line the zero with the pupil of your left eye, Take the reading where the pupil coincides with the right eye.
If you do have the PD on your prescription but you see two numbers. Don’t panic! All they really mean (close,far). The first value is for reading and the second value is for distance. These usually occur in people who have bi-focals. When you make a purchase online, if you’re unsure in which of the 2 values to put for the PD, since the website’s generally ask for just one number. Remember, the lowest is for reading, the higher is for distance. If you’re just not sure what kind of glasses you need, enter the lowest of the two, it’s usually the safest bet.