pupillavstånd

Pupillavstånd, often abbreviated as PD, refers to the distance between the centers of a person's pupils. This measurement is crucial for correctly fitting eyeglasses and contact lenses, as well as for certain vision therapy exercises and some medical examinations. A person's PD is typically measured in millimeters and can vary significantly from individual to individual. There are two main types of pupillary distance: monocular PD, which is the distance from the center of one pupil to the bridge of the nose, and binocular PD, which is the total distance between the centers of both pupils. Optometrists and opticians routinely measure PD during eye exams. This can be done manually using a ruler or a specialized device called a pupillometer. Digital cameras and smartphone apps are also increasingly used for PD measurement. An accurate PD ensures that the optical centers of prescription lenses align correctly with the wearer's pupils, which is essential for clear and comfortable vision and to prevent eye strain or headaches. Deviations in PD measurement can lead to improper lens centering, potentially causing visual distortions.