Zenni Optical - Most optometrists don't measure your PD, so we've created this handy guide to help do it yourself! http://bit.ly/YYB2oz #ZenniOptical #DIY | Facebook
Glasses Frames and Lenses - How to use a PD ruler
Zenni Optical PD Ruler PDF | PDF | Eye | Visual System
Answering Your Top Questions About Pupillary Distance (PD)