LY-9AT PUPIL DISTANCE METER

The pupillary distance meter is a measuring instrument used in optometry to measure the distance between the two pupils of the human eye.

The interpupillary distance can be divided into binocular interpupillary distance and monocular interpupillary distance. Interpupillary distance refers to the distance from the center of the pupil of the right eye to the center of the pupil of the left eye. Monocular interpupillary distance refers to the distance from the center of the pupil of either the right or left eye to the centerline of the bridge of the nose. Individuals with strabismus, especially those who require progressive multifocal lenses, need to measure their monocular interpupillary distance.

The measuring principle of the pupillary distance meter involves illuminating a visual mark with a light source. The mark is then imaged at a specific working distance in front of the patient's eyes using an optical system.

Consequently, the light forms a reflective point on the surface of the patient's left and right corneas. The optometrist can observe these two reflective points through the eyepiece and adjust the measuring button until the benchmark hairspring aligns with the reflective points of the patient's left and right eyes. The patient's interpupillary distance can then be obtained and displayed on the screen.