How are interpupillary distance and pupil height measured_

How are interpupillary distance and pupil height measured?

1. Definition of pupillary distance Pupillary distance (papillary distance) refers to the distance between the center of the pupils of the two eyes, or the distance between the center of the pupil when the eyes are facing forward and the line of sight is parallel. It is generally represented by the English letter abbreviation "PD", and the unit is millimeters (mm). 2. Classification of pupillary distance Interpupillary distance is divided into binocular interpupillary distance and monocular interpupillary distance. Binocular interpupillary distance is 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 is the distance from the center of the pupil in the right or left eye to the nasal centreline, respectively. One-eyed and strabismic eyes, especially those with progressive multifocal lenses, need to measure their uniocular interpupillary distance. Interpupillary distance is divided into distal interpupillary distance and near interpupillary distance. Distant interpupillary distance refers to the interpupillary distance when the patient looks at a distance, that is, the distance between the center of the pupils of the two eyes when they are looking at infinity at a distance. Near interpupillary distance (NCD) refers to the distance between the center of the pupil when the patient fixes at a near target, that is, when reading 30~40cm in front of the eye or working at close range. The near interpupillary distance is always smaller than the distal interpupillary distance. 3. Definition and classification of pupil height Pupil height is the abbreviation of the center height of the pupil, which refers to the distance from the visual axis of the eye through the lens to the lowest point at the bottom of the lower edge of the frame. There are two types of pupil height: distant pupil height and near pupil height. When there are no special requirements, the pupil height of far-use glasses is generally shifted by 1.5~2mm up the geometric center of the frame (optical center), and the pupil height of near-use glasses is moved down by 1.5~2mm in the geometric center of the frame. However, when formulating progressive multifocal glasses, there are strict requirements for pupil height, which need to be measured carefully and repeatedly. Fourth, the use of the interpupillary distance ruler 1, the measurement of the distance of the interpupillary distance In the pupils of the two eyes in the physiological state of the party, the following two methods are usually used to measure. (1) The distance from the center of the pupil of the right eye to the midpoint of the pupil of the right eye. (2) The distance from the outer edge of the pupil of the right eye (temporal side) to the inner edge of the pupil of the left eye (nasal side) or from the inner edge of the pupil of the right eye (nasal side) to the outer edge of the pupil of the left eye (temporal side). 2. Routine measurement steps of distance interpupillary distance (1) The examiner and the patient are seated facing each other at a distance of 40cm, so that the sight of the two people is kept at the same height. (2) The examiner holds the IPF or ruler with the thumb and index finger of the right hand, rests the rest of the fingers on the patient's cheek, and then places the IPR at the lowest point of the nose bridge and slightly inclines along the angle of the nose bridge. (3) The examiner closes the right eye, so that the patient's right eye fixes on the examiner's left eye, and the examiner aligns the "zero" position of the interpupillary ruler with the center of the pupil of the patient's right eye when the left eye fixes on the patient's right eye. (4) The examiner opens the right eye and closes the left eye, so that the patient's left eye fixes on the examiner's right eye, and the examiner accurately reads the value of the pupil ruler in the center of the patient's left eye when the right eye fixes on the patient's left eye. (5) The examiner repeats step (3) to confirm that the "zero" position of the interpupillary ruler is aligned with the center of the pupil of the patient's right eye. If correct, the value read in step (4) is the patient's interpupillary distance. 3. Interpupillary distance measurement of strabismus (1) The examiner and the patient are seated facing each other at a distance of 40cm so that the sight of the two people is kept at the same height. (2) The examiner holds the IPF or ruler with the thumb and index finger of the right hand, rests the rest of the fingers on the patient's cheek, and then places the IPR at the lowest point of the nose bridge and slightly inclines along the angle of the nose bridge. (3) The examiner closes the right eye, makes the patient's right eye look at the examiner's left eye, and the examiner covers the patient's left eye with his left hand, and aligns the "zero" position of the interpupillary ruler at the center of the pupil of the patient's right eye. (4) The examiner opens the right eye and closes the left eye, so that the patient's left eye fixes on the examiner's right eye, and the examiner covers the patient's right eye with his left hand, and reads the value of the interpupillary distance ruler in the center of the pupil of the patient's left eye, which is the patient's interpupillary distance. 4. Interpupillary distance measurement in other cases (1) The size of the two pupils is unequal: the distance from the inner and outer edge of the right pupil to the outer and inner edge of the left pupil can be measured separately, and then the average of the two readings can be taken. (2) Asymmetry of the two pupils: that is, the pupils of one or both eyes are not in the center of the iris, which is mostly seen after trauma or geriatric cataract surgery, and the interpupillary distance is difficult to measure, so you can try glasses to determine its value. 5. Measurement of near interpupillary distance (1) The examiner and the patient should be seated facing each other at a distance of 40cm, so that the sight of the two people is kept at the same height. (2) The examiner holds the IPF or ruler with the thumb and index finger of the right hand, rests the rest of the fingers on the patient's cheek, and then places the IPR at the lowest point of the nose bridge and slightly inclines along the angle of the nose bridge. (3) The examiner closes the right eye, makes the patient fix both eyes on the left eye, and uses the left eye fixation to align the "zero position" of the interpupillary distance ruler at the center of the pupil of the patient's right eye. (4) The examiner opens the right eye, still asks the patient to continue to look at the left eye, and uses the right eye to read the value on the center of the pupil of the patient's left eye. (5) Repeat steps (3)~(4) three times, and take the average value as the near interpupillary distance. 6. Measurement of interpupillary distance in one eye: When the bridge of the patient's nose deviates significantly from the midline, the measurement of interpupillary distance in one eye is required. (1) The examiner and the patient should be seated at a distance of 40 cm from each other, so that the sight of the two people is kept at the same height. (2) The examiner should measure the midline of the partial bridge of the nose from the center of the pupil of one eye to obtain the interpupillary distance of one eye. (3) Accurate monocular interpupillary distance measurement requires the use of a pupillary distance meter. 7. Measurement of pupil height (1) Let the patient wear the selected frame for plastic surgery and calibration. (2) The optician and the patient should be seated facing each other at a distance of 40 cm, so that the sight of the two people is kept at the same height. (3) The optician holds the IPA ruler vertically with the thumb and forefinger of the right hand, and rests the rest of the fingers on the customer's cheek. (4) The optician measures the left eye and fixes it with the right eye, so that the patient's left eye fixes on the right eye of the optician, and the optician aligns the "zero" position of the pupil ruler to the center of the pupil, and reads the value on the pupil ruler at the lowest point at the bottom of the groove at the lower edge of the frame, which is the pupil height of the eye. (5) Measure the pupil height of the other eye in the same way. 8. Precautions (1) The line of sight between the examiner and the patient should always be at the same height during the measurement. (2) Do not touch the eyelashes of the affected eye at the interpupillary distance ruler, so as not to cause the patient's eyes to close the reaction. (3) When the IPF determines the "zero position", be sure to hold the IPD steady to avoid moving. (4) Let the affected eye fix in the specified direction and not make it drift. (5) Generally, it should be measured 2~3 times repeatedly to take its accurate value. 5. The use of the pupil distance meter is the common corneal reflex pupil distance meter, and its structure is: (1) frontal part, (2) nasal bridge, (3) observation window, (4) visibility switch key, (5) power switch, (6) PD/VD switch key, (7) PD adjustable key (left and right), (8) fixation distance key, (9) PD pointer, (10) corneal reference line, (11) battery box, (12) numerical display window, (13) cover plate key, (14) green fixation target. 1. First of all, according to the requirements of measuring the distance or near interpupillary distance, adjust the fixation distance button to the fixation distance value 鈭?or the position of the 30mm mark 鈻? 2. Turn on the power switch. 3. Place the forehead and bridge of the nose of the interpupillary meter on the patient's forehead and bridge of the nose. 4. Ask the patient to look at the green light inside the visual marker. 5. The examiner observes the reflex highlights on the pupil of the affected eye through the observation window, and then moves the left and right PD adjustable keys respectively to align the PD pointer with the corneal reflex highlights of the two eyes. 6. Read the value displayed in the numerical display window. The R value represents the distance from the center of the nose bridge to the center of the pupil of the right eye, representing the interpupillary distance of the right eye. The L value represents the distance from the center of the nasal bridge to the center of the pupil of the left eye, representing the interpupillary distance of the left eye. The value in the middle represents the distance between the pupils of the two eyes, i.e., the interpupillary distance between the two eyes. The unit is mm. 7. If you need to measure the interpupillary distance of one eye for the strabismus eye, you can adjust the instrument to measure, that is, use the distant part to observe the pupil, and use the near part to read the PD value. 8. Using the visual switch key, you can wear multifocal glasses for measurement, that is, use the distant part to observe the pupil, and use the near part to read the PD value. 9. Switch the PD/VD button to measure the distance between the corneas. 10. Precautions (1) Do not touch or accumulate dirt with your fingers at the observation window or measuring window. When cleaning, gently wipe off with lens paper and a little alcohol. (2) The numerical display window adopts liquid crystal display to avoid being oppressed by external force to avoid damage.