To measure pupillary distance with a pupillary distance ruler, start by positioning the ruler against your eyes, allowing it to rest on the bridge of your nose, according to Coastal.com. Beginning at zero millimeters on the ruler, align the point with your right or left pupil. When you have aligned the 0-millimeter mark on the ruler with the right or left pupil, the mark that rests in the center of the left or right pupil is your pupillary distance.
To ensure measuring your pupillary distance accurately, you must look straight ahead, explains Coastal.com. When reading the ruler yourself, look at yourself in a mirror. If someone else is reading the measurement, the person's eyes must be level with your eyes. Confirm the measurement by repeating the measuring steps a few times.
When eye care professionals examine patients' eyes, they usually take pupillary distance measurements, even though the measurements are not on the lens prescriptions, notes Coastal.com. Contact your examining eye care professional to ask for your measurement before attempting the measurement procedure on your own.
Pupillary distance is the distance between the pupils of your eyes, according to Zenni Optical. Pupillary distances in adults range from about 54 to 74 millimeters and in children the range is about 43 to 53 millimeters. Eye care professionals use the measurements to match the optical center of patients' prescription lenses to their eyes.