Your PD should be exact. If your lenses aren't centered correctly, they can cause discomfort and eye strain. A small margin of error might not cause problems, but it's better to be as accurate as possible.2020-05-13
How much can your PD be off?
During the day, your PD can vary about 3-4 mm depending on your viewing distance. For instance, if your PD is 61 mm when looking at distant objects (i.e. street signs, chalkboard, TV, etc.), it narrows to 57-58 mm when viewing objects within 16-24 inches from your eyes.2018-10-23
What if PD is off by 2mm?
If the PD measured was 2mm off initially, by using a millimeter rule, the net cumulative error might be 4.5mm or more. However, you were not aware of the original 2mm error. A corneal reflection pupillometer is worth the investment.
Does pupillary distance round up or down?
Starting with the right eye, line up the zero end of the ruler at your pupil; measure the distance from your right to your left pupil. The millimeter number that lines up with your left pupil is the measurement you want. That number is your PD. Jot it down.
What if I measure my PD wrong?
When you get glasses made, the pupil distance measurement is taken to ensure that the lens center is in line with your pupil center. ... The wrong PD can induce eye strain, fatigue, headaches and blurry vision.2017-12-26
What if pupillary distance is off by 1mm?
What if PD Is Off by 1mm? When the PD is wrong by a millimeter the outcome for the wearer will be very different depending on the lens power in the glasses. A wrong pupillary distance is measured in millimeters. This distance multiplied with the lens power equals the deviation a wrong PD produces.