Device for measuring pupillary distance

Abstract From the Canadian patent

Since a certain relationship exists between a pupillary distance at a viewing distance and a pupillary distance at another viewing distance, the pupillary distance at a desired viewing distance can be obtained by making a predetermined correction in the results of a pupillary distance measurement at a fixed viewing distance without requiring a convexed lens in the device to be moved. The fixed viewing distance is preferably set at a small value such as 1 to 2 meters so that problems such as filure in forming a fused image due to machine near sightedness can be avoided. The device has sighting mark forming means which can be installed at any portion of the measuring device for enabling easy …