How to know if the interpupillary distance of glasses is accurate, how to know the interpupillary di

How to measure 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 interpupillary ruler or ruler with the thumb and index finger of the right hand, and the rest of the fingers are leaning on the patient's cheek, and then places the interpupillary ruler 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 pupil ruler with 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 the examiner's right eye, and the examiner accurately reads the value of the interpupillary distance ruler in the center of the pupil 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 whether the "zero position" of the interpupillary distance ruler is aligned with the center of the pupil of the patient's right eye. If it is accurate, the value read in step 4 is the interpupillary distance of the patient.

There are four parts to the process of fitting glasses: an accurate optometry, choosing a frame, lens thickness, and adjusting the glasses.

1. Accurate optometry sheet. The data of the optometry sheet includes the degree of myopia or farsightedness of the left and right eyes of the optician, as well as the interpupillary distance of both eyes. If there is astigmatism, the degree of astigmatism and the axis position of the astigmatism are also required.

2. Be cautious when choosing a frame. The shape of the spectacle frame is very important, in principle, a square or rectangular face is suitable for an oval or rectangular frame with a certain curvature, a round face is suitable for any shape of frame other than a circle, and an oval or melon seed face is generally suitable for any shape of frame. Frame size is also important, and only those that fit your size are more comfortable.

The larger the frame, the heavier the weight, and the higher the requirements for the refractive index of the lens.

3. Whether the glasses are suitable for you depends on the thickness of the spectacle lens. The thickness of the lens is directly related to the refractive index of the lens. The higher the refractive index at the same power, the thinner the lens.

The refractive index can be selected within 300 degrees, the refractive index can be selected at 300-500 degrees, the refractive index can be selected at 500-800 degrees, and the refractive index can be selected above 800 degrees74 refractive index.

4. After the glasses are selected, you also need to make adjustments according to your face shape when you take the glasses, such as whether the nose pads fit the bridge of the nose, whether the hooks of the temples are just hanging on the ears, whether the glasses are chucked, etc., so that the glasses are adjusted to be more comfortable to wear.

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Interpupillary distance refers to the distance between the reflective points of the pupils of two eyes. The distance between the optical center point of the spherical lens of the two eyes is the interpupillary distance, and if the simple cylindrical lens and the flat lens without power do not have the optical center point, there is no need to measure the interpupillary distance; If the lens has a prescription, you need to measure the optical center point of the lens with a focimeter to measure whether the distance between the optical center point of the two lenses is the same as the interpupillary distance of the eye.

The size of the interpupillary distance in normal people varies from 55 to 70 mm. If the interpupillary distance is large, the three-dimensional effect may be slightly better. If the interpupillary distance is small, stereoscopic vision may be a little worse. In general, there is a difference in the interpupillary distance of each person, and there is a difference between the interpupillary distance and the near vision.

When looking at a distance, the eyes are spread outward, and the interpupillary distance is slightly larger. If you look closely, the eyes are geometrically shaped and accumulate inward, and the measured interpupillary distance is slightly smaller. With glasses, it is necessary to consider the interpupillary distance between seeing far and near, and take the intermediate value, so that when people can see, the interpupillary distance can just adapt to the requirements of people's vision, and they will not feel dizzy.

Interpupillary distance is simply the distance between the pupils of each eye. The eyes of a normal person look at the same object, and the object is imaged at the retina of the two eyes, and overlaps in the optic center of the brain to become a complete single object with a three-dimensional sense, this function is called binocular monovision. However, in the process of binocular monovision, infants and young children are easily affected by external factors, resulting in one eye fixing on the target, and the other eye is deviated and cannot look at the same target, so strabismus occurs.

In medicine, the inward squint of the eyeball when looking at an object is called esotropia, which is commonly known as "cross-eyed".

When wearing glasses, you need to measure the interpupillary distance, and the interpupillary distance is divided into: distal interpupillary distance, near interpupillary distance, and commonly used interpupillary distance. When measured, these three interpupillary distances are measured at a certain distance.

For patients with nearsightedness or farsightedness, this parameter needs to be considered when wearing glasses. That is, the distance between the centers of the two lenses (optical center distance) should match the interpupillary distance of the patient, otherwise, even if the prescription is correct, the patient will feel uncomfortable after wearing glasses and affect vision.

Distant measurements. When the pupils of both eyes are in a normal physiological state, the following two methods are usually used.

The distance from the center of the pupil of the right eye to the midpoint of the pupil of the left 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 the distance from the inner edge of the pupil of the right eye (nasal) to the outer edge of the pupil of the left eye (temporal side).

First of all, I would like to introduce to you what IPD is. Interpupillary distance is the distance between the centers of the pupils of the two eyes when the gaze of the two eyes is facing or parallel. The purpose of optometry measurement of interpupillary distance is mainly to make the optical center distance of the equipped lens consistent with the interpupillary distance, so as to ensure that the eye can see through the optical center.

Therefore, IPD is crucial in choosing the right frame.

Step 1: The examiner and the subject sit facing each other and place their eye heights at the same level. The tester verbally directs the subject's gaze and performs the test.

Step 2: The tester holds the eye shield in his left hand, covers his right eye, and asks the tester to fix both eyes on the pupil of the tester's left eye. The examiner holds the ruler in his right hand and places it in a horizontal position on the plane of the subject's mirror.

Observe the outer (or inner edge) of the pupil of the right eye of the person being measured, and adjust the position of the ruler to the left and right so that the zero tick mark of the ruler is tangent to the outer (or inner edge) of the pupil of the right eye.

Step 3: Maintain the position of the ruler steadily, move the eye visor from the right eye to the left eye, and ask the test subject to fix both eyes to the pupil of the tester's right eye. The examiner fixes the inner (or outer) edge of the pupil of the subject's left eye with his right eye and reads the tick mark tangent to the ruler.

The distance from the zero tick to this is the line of sight being measured.

Have you learned the above methods of measuring interpupillary distance? If it's not clear, it doesn't matter, watch it a few more times, practice it a few more times and it will be clear. Finally, I would like to remind you that since it is a manual measurement of interpupillary distance, it is inevitable that there will be errors, and it is recommended to measure several times to determine the most accurate value.

Interpupillary distance mainly refers to the distance between the two eyes on the visual axis, that is, the distance generated by the midpoint of the eyes when the two eyes look at distant objects, which is called interpupillary distance. Interpupillary distance includes near interpupillary distance and distant interpupillary distance, usually about 2-3mm apart. If the face is also wider, the interpupillary distance may be more different, and if the face is smaller, the interpupillary distance may be smaller.

If you feel that the interpupillary distance is not appropriate, the first thing you may do is to wear glasses, and you will feel a little dizzy when you look at things, especially when you look near or far alternately, this symptom will be more obvious. In general, it may be difficult to measure by yourself, so you should go to a hospital or an optical store to measure the interpupillary distance of your eyes and glasses. If there is a lot of difference between the two, it is not suitable and you need to replace the glasses and lenses.

Myopia glasses with accurate interpupillary distance are comfortable to wear. The error between the optical center and the interpupillary distance of myopia glasses should not exceed 2mm.

Measurement method: 01

Measuring the optical center of myopia glasses yourself requires a dot light source and a ruler.

The light source can use the illuminated ear pick, remove the front ear scoop, and use only its lamp.

If you shine a light on your glasses, there will be two spots of light on the glasses.

Adjust the position of the light source on the lens so that the front and rear light spots are close to each other and coincide.

When the front and last two points of light completely coincide, the middle of this point of light is the center of light.

By measuring the optical centers of the two lenses with a ruler, you can calculate whether the optical center matches the interpupillary distance.

Of course, the error of this measurement will be relatively large, and professional equipment is still required for accurate measurement.

Many people don't pay attention to their interpupillary distance when they wear glasses. In fact, interpupillary distance is very important. If a person wears glasses with incorrect interpupillary distance for a long time, it will not only deepen myopia, but also cause astigmatism, which can easily lead to visual fatigue and even dizziness and headaches.

Therefore, wearing glasses must be suitable for interpupillary distance. If similar symptoms occur, they should be corrected as soon as possible. Attention should be paid to eating more things that improve eyesight, which is helpful for the recovery of the eyes.

In addition, attention should be paid to the reasonable arrangement and combination of dietary nutrition. To maintain a good state of mind, you can place green potted plants in the bedroom lamp to relieve eye strain.

In order to align the optical center distance of the lens with the interpupillary distance of both eyes, it is comfortable for the wearer to wear. According to the national standard for assembling glasses, it is still acceptable to transfer the center within a certain range.

If the distance between the optical center of the lens and the interpupillary distance does not coincide, the scenery seen through the lens will be deformed, distorted and blurred, which is the so-called prism effect, which is very harmful to the eyes. Similarly, the inappropriate interpupillary distance of the lens will cause dizziness and nausea, of course, the improper frame will also directly affect the position of the lens, which will also cause eye fatigue and cause damage to the eyes.

Due to the deviation between the interpupillary distance of the large-framed glasses lens and the interpupillary distance of the human eye, people with small interpupillary distance wearing such glasses will cause the pupil to deviate from the center of the lens, resulting in blurred vision, visual fatigue, and easy to cause myopia.

The interpupillary distance error of online shopping myopia glasses is large, and long-term wearing will increase the degree.

After testing, the prescription of the 4 pairs of glasses was consistent with the prescription provided by the reporter. However, the interpupillary distance of 4 pairs of glasses has deviated, and the largest difference reached the 24th of January, the relevant person in charge of the optometry center of Beijing Tongren Hospital said that the incorrect interpupillary distance is manifested as the displacement or deformation of the object through the lens vision, and there is an uncomfortable feeling after wearing. What you see is not the clearest.

The higher the power, the greater the distortion, which can also cause vertigo.

In addition, the test showed that all 4 pairs of glasses were ordinary spherical lenses. "To put it simply, ordinary spherical surfaces are prone to wear and tear, have a short lifespan, and wear them for a long time will affect your vision. The optometrist said.

The relevant person in charge of the Tongren Optometry Center said that aspherical lenses are more comfortable and the mirror surface is thinner. Ordinary spherical lenses, if the prescription is high, the lens will be very thick, and it will be uncomfortable to wear.

Before explaining the importance of interpupillary distance in detail, we must first understand three concepts: "interpupillary distance", "geometric center distance", and "optical center distance", which are actually not the same, "interpupillary distance" is the distance between the two eyes of a person, "geometric center distance" refers to the distance between the geometric center points of the two lens circles on the left and right sides of the spectacle frame, and "optical center distance" refers to the distance between the optical center points of the lens after the glasses are fitted. In a nutshell:

"Interpupillary distance" is for "people"; Geometric Center Distance is for Frames; "Optical center distance" refers to "glasses with good lenses". Qualified glasses are the "optical center distance" of glasses with good lenses, which should be aimed at the "interpupillary distance" of the person, so that both eyes can see through the optical center of the lens, which is the most comfortable. If the amount of interpupillary distance is inaccurate, or the optical center distance of the lens is not accurate, it will produce a "prism" effect, which will cause the image to displace, causing many symptoms

In mild cases, double vision, dizziness, dispersion, and inability to see for a long time occur, or squint is induced, causing the eye position to shift.

1. The surveyor and the person being measured sit facing each other, and the person being measured looks at a fixed object 5 meters or more behind the surveyor.

2. The measurer holds the right end of the ruler with his right hand, and the "zero" scale on the left side of the ruler is aimed at the center point (pupil) of the black eye of the right eye of the measured person, and then observes the scale on the ruler corresponding to the center point of the black eye (pupil) of the left eye of the measured person, accurate to the millimeter, and the interpupillary distance of the measured person is at this moment.

3. Repeat step 2, measure a total of 3 times, and take the average value, so that the conventional distal interpupillary distance is measured.

1. The surveyor closes the right eye, the left eye is open and open, the measured person covers the left eye with a shield, the right eye looks directly at the left eye of the measurer, and when the measurer looks at the right eye of the measured person with the left eye, the 0 of the ruler is aligned with the center of the pupil of the tester.

2. The surveyor closes the left eye, the right eye is opened, the measured person covers the right eye with a shield, the left eye looks directly at the right eye of the measurer, and the surveyor uses the right eye to look at the left eye of the measured person when reading the center value of the ruler, and the pupil alignment value of the left eye is the interpupillary distance of both eyes.