To place an order, you will need a prescription for corrective eyeglass lenses and your pupillary distance (PD). A contact lens prescription cannot be used to make eyeglasses.
When you have your eyes examined, request the PD (pupillary distance) from the person who does your exam. The pupillary distance is the distance in mm between the centers of your pupils. Corrective lenses can't be made without a PD. It’s used to position the optical center of the lens so that you will be able to easily see through the lens, and to center the correction in front of the pupil of your eye in the eyeglasses. If a pair of frames cannot accept your PD, you can't simply change your PD simply to make it work because you will not be able to see through a lens produced with an incorrect Pupillary Distance.
The correct PD is particularly important for a multi-focal lens (bifocal and progressive), as there are multiple viewing fields which are adjusted on the basis of the PD supplied.
The PD is often left off the prescription, although it’s usually recorded in your file. Having your PD empowers you to purchase eyeglasses from any supplier, not just with the place where you got your exam. It is your right to have your PD - you paid for it with your prescription.
PDs may be indicated in a variety of ways. You will often be given a single number – this should be your distance vision PD and is what you will need for eyeglass orders on our site. Most adults have a PD between 53 and 70, and children will be between 41-55. You might be given two numbers such as 63/60. This would mean that you use 63 as your PD for distance vision. The smaller number would be used only when converting the prescription to single vision reading glasses. You may be given fractional PD measurements, right side and left side, and split PDs may be written as 30.5/31, for example. Simply add the two numbers together to get your distance vision PD.
SPH - Spherical - Provides the depth of the focal field in the lens.
A negative sign in front of the number indicates that you're nearsighted, which is the case with the majority of people who wear corrective lens. In nearsightedness, the thinnest part of the lens is the center, and the wider the lens becomes, the thicker it will be at the outer edge. If you're concerned about the outer edge thickness of the lens, you would be advised to consider narrower lens widths.
With a positive sign preceding the Spherical number, you're farsighted, and the thickest part of the lens is in the center. The size of the lens is also important, because the larger the lens, the thinner the edge will be. This may eliminate the consideration of half rim frames because the lens may become too thin to provide for the groove, to carry the filament, to help keep the lens in the frame.
Cyl and Axis - The two designations will be included if you have an astigmatism, an irregularity in the shape of the eye, which causes shape distortion in the viewed image. Cyl will describe the amount of correction you need to overcome this, and Axis is the angle at which the correction is placed. The Axis will be recorded as a degree reading between 1 and 180 degrees.
If you find the designation "Sph" written in the Cylinder area of the prescription, it simply means that the eyeball is spherical, and there is no correction for astigmatism needed in that eye.
back to Rx S.V