Aug 31, 2015 How to Measure Your Pupillary Distance (PD) for New Designer Reading Glasses Ensure the Perfect Fit When Buying Reading Glasses Online The term "pupillary distance" refers to the distance between your pupils. This measurement is used to determine where the optical centers of your eyeglasses should be placed in order to optimize your vision. To measure your pupillary distance before purchasing quality reading glasses, follow the steps below. Ask a friend for help. Whether you’re ordering designer reading eyewear online or an inexpensive pair of prescription sunglasses, you will need a friend or family member to help you measure your pupillary distance. Place a ruler horizontally across the top of your nose. Begin by placing a ruler (that measures in millimeters) across the top of your nose. Ask your friend/assistant to stand arm's length away from you. Look straight ahead while your assistant writes down the measurements of the center of your pupils. Measure the distance. Ask your assistant to place the ruler's 1mm mark in front of the center of your left pupil. Next, he or she should make note of the number that lines up with the center of your right pupil with the ruler equidistant from the front of both eyes. Make sure that you are looking straight ahead throughout this process. Re-check the measurement. Before you start shopping for eyeglass frames for sale online, re-check the measurement between the pupils a few times to ensure accuracy. Take advantage of the assistance and get other measurements, too. Most eyewear retailers and wholesalers (including I Heart Eyewear) will list the measurements of the frames and lenses. For example, lens width, lens height, bridge width, and temple length are usually listed in the product description. Have your assistant help you determine those measurements, and buying glasses online will be easier than you ever thought possible! Find Best-Fitting Eyeglass Frames Today! The I Heart Eyewear team would love to help you on your journey to clearer (and hipper) vision. Our online catalog offers a plethora of stylish eyewear and accessories, and we’re also available by email to answer questions you may have about our eyewear sizing, and help you find the perfect fit for your pupillary distance and face shape.