Eyeglasses Fitted with Pupillary Distance
According to Wikipedia, Pupillary Distance (PD) or interpupillary distance (IPD) is the distance (the industry standard is to measure in millimeters) between the centers of the pupils in each eye. This measurement is used when preparing to make prescription eyeglasses. Positioning lenses correctly in relation to the center of the pupils is especially important for higher powered lenses due to the location of the optical centre of the lenses. It can also be relevant to binoculars: they must be adjusted to suit the user’s IPD; and the minimum allowed by some binoculars is still too great for people with a small IPD.
Someone with training in the field of optics can accurately measure your pupillary distance, or you can make an approximate measurement yourself using a ruler, with someone’s assistance or a mirror. The measurement will usually be taken twice: 1st with the patient focusing at a distance, and 2nd with the patient focusing at something close. The second measurement is used for reading glasses, and bifocals however the rule of thumb is that the so-called “near PD” will be 4 millimeters less than the “far PD” when the far PD is over 60mm, or 3 millimeters less than the far PD when the far PD is under 60mm. It is recommended, due to accuracy, to measure the PD with a pupilometer, however some practitioners take preliminary measurements with a millimeter ruler placed across the bridge of the nose. You can also measure your PD using a suitable photo and an online pupilometer.
In very young children and babies, where the patient is unlikely to stay still, the optical professional will typically measure from one medial canthus to the other lateral canthus. In this case, measurements are often inaccurate by a few millimeters.
I think this sounds like an excellent way to get a great fit on eyeglasses. It makes the eyeglasses more individual and made for the wearer. Check out zennioptical.com for more info and a great selection of sharp looking eyeglasses!
Posted by: stepherz | 07-29-2010 | 09:07 AM
Posted in: Stepherz the Sellout
