With the presence of online ordering, many patients are asking their doctors of optometry for a PD (pupillary distance) measurement, which is the distance between the eyes.
While a PD measurement can be performed during your visit to the doctor of optometry’s office, it is not part of the prescription as it has no clinical relevance. A PD should be performed during the fitting of the glasses by an optical dispenser. The PD will differ depending on the purpose of the glasses and the type of lenses. For example, reading glasses will require a different PD measurement than a pair of driving glasses or computer glasses.
A PD is also only one component of many measurements that are required during the proper fitting of a pair of glasses. Your fitting will also include:
- Segment or OC height (determines where the lens will be positioned in the frame).
- Vertex distance (distance between the frame and the cornea).
- Pantoscopic tilt (amount of tilt on the front of the frame).
- Wrap angle (amount the frame is curved towards your face).
- Base curve (curvature on the front surface of the lens).
It will also take into consideration the frame size, width, bridge contour, temple length, lens type, index and material.
As a PD measurement is not part of the optical prescription, some offices charge a fee for this service. This can be confirmed with the clinic staff.