I am blessed to have good eye sight and don't need to go through any hassles of having my eyes check. I have read different stories from people who had their eyes checked from eye specialist. Not all of them experienced good treatment and complete eye check up. I only experienced having my eyes check during my medical as per requirement for my US visa. However, the PD or pupillary distance measurement should be done for a patient that needs prescription eyeglasses. Unfortunately, there are some eye doctor don't do this process and don't let their patient know what PD is. The PD or Pupillary Distance is the distance between the pupils of the eyes, center to center, in Millimeters. This measurement is needed to ensure proper eyeglass fitment. Well, I have read online a growing thread of discussion shared by different eye care professionals about certain topic which is the Pupillary Distance. They have mixed thoughts and reaction to the topic as well as different opinions about it. It shows that some eye doctor don't give their patients the PD they want to get prescription eye glasses. Probably they want them to buy their prescription eye glasses to them. But, for practical reason other choose to buy their prescription eye glasses to other optical like Zenni for they have such inexpensive and quality eyeglasses. But Opticians don't want you to order from ZenniOptical.com. Zenni is a trusted company when it comes to eye glasses. They have been in business for years and providing affordable and quality product is their best interests at heart. Prescription eyeglasses are a health item necessity for most wearers, and to that end Zenni take considerable pride in offering a very high quality product at truly unheard of affordable prices.