Sometimes, the most *****s' PD's are around 59 to 72, if you measured is smaller, such 44.5, 51, 38 or 51. It is abnormal. If you could not find a ruler with millimeters, please use the inches ruler to measure, and then convert inch into millimeter. As a guideline: 1 inch=25.4 mm

Thanks for your information. Could you please aslo advise how can I measure my PD value by myself?

You can measure your PD by your self simply by looking in the mirror. Place a regular ruler on the bridge of your nose and measure the distance between the center of your pupuils (the black dots in the middle of your eyes). This way is not recommended to obtain PD, we recommend to have your PD by a professional.