Please consider the following before you make a purchase online.
PD or pupillary distance is the distance between your pupils, or the dark center of your eyes. This measurement is used to indicate where your eyes sit relative to a pair of glasses.
Why is this important? Your pupil distance helps determine the optical center (OC) of the lenses that are being made to your prescription. Your prescription is only accurate if you’re looking through the OC when you put your glasses on.
What happens if the PD is incorrect? If glasses are ordered with an incorrect PD, you will most likely not be looking through the OC of the glasses you order. This can cause your prescription to seem blurry or even cause eye strain and headaches. These symptoms are worsened the higher your prescription is because the strength difference is more noticeable.
What if I wear trifocals, lined bifocals or progressive lenses (no line bifocals)?
Trifocals, lined bifocals and progressive lenses need an additional measurement called a seg height. This measurement indicates where the bifocal sits relative to your pupil. This measurement is taken differently for lined trifocals, lined bifocals and progressives. If this measurement is incorrect, the reading strength of your lens may be situated too high or too low when your lenses are made, causing you to see blurry for distance or reading, depending on the error.
Glasses are medical devices designed to help you see to your best potential. Therefore, it is important that a knowledgeable professional is involved in selecting a frame that fits well and ensuring that all measurements are taken accurately in order for you to see your best.
If you have additional questions please contact our optical dispensary at (219) 922-6226.