Abstract: the adjustment ability of the eye refers to the refractive power that can be increased by the maximum adjustment of the eye. The change of the adjustment power directly affects the clarity of people’s eyes. Its size can be expressed by the nearest distance that the eye can see the object, that is, the near point., When the object moves from 6 meters away to within 6 meters, the light entering the eye changes from parallel to divergent. After refraction, the object image must be behind the retina, and the vision will become blurred. But in fact, as the object moves closer, a series of activities occur in the eye, so that the object can still be imaged on the retina, which is called eye regulation. The adjustment of the eye mainly depends on the convex lens to increase the refractive power., The adjustment ability of the eye refers to the refractive power that can be increased by the maximum adjustment of the eye. The change of the adjustment power directly affects the clarity of people’s eyes. Its size can be expressed by the nearest distance that the eye can see the object, that is, the near point., The concept of regulation: regulating apogee: when the human eye looks at the object, the image is in the macula of the retina, and the farthest point that the human eye can see when the regulation is still is the regulating apogee; At rest, the light at infinity is focused on the retina., Near point of adjustment: the closest point that the human eye can see with all its adjustment ability. When the adjustment ability is maximum, the light emitted from the near point is just focused on the retina., The maximum adjustment force that can be produced by the human eye is the difference between the refractive power when looking at the far point and the near point., The closer the proximal point of the normal eye, the greater the adjustment ability, the better the elasticity of the lens. Early in life, the adjustment of the human eye is great, about 15. 00D～25。 00D, which decreases gradually with the increase of age, and decreases by about 0 every year. 25D～0。 The amount of adjustment of 40d. In this way, at the age of about 40, the adjustment force of the eye is not enough to comfortably complete the close work. The elasticity of the lens decreases with age, and the proximal point becomes farther. For example, the near points of 10, 20 and 60 are 8 respectively. 8 cm, 10 cm. 4 cm and 83. 3 cm. The old people are called presbyopia because they see things far away, but it is difficult to see things near.,
when an object moves from 6 meters away to within 6 meters, the light entering the eye changes from parallel to divergent. After refraction, the object image must be behind the retina, and the vision will become blurred. But in fact, as the object moves closer, a series of activities occur in the eye, so that the object can still be imaged on the retina, which is called eye regulation. The adjustment of the eye mainly depends on the convex lens to increase the refractive power. The adjustment ability of
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eyes refers to the refractive power that can be increased by the maximum adjustment of the eyes. The change of adjustment power directly affects the clarity of people’s eyes. Its size can be expressed by the nearest distance that the eye can see the object, that is, the near point.
concepts related to regulation:
regulation distal point: when the human eye looks at the object, the image is in the macula of the retina, and the farthest point that the human eye can see when the regulation is still is the regulation distal point; When the adjustment is still, the light at an infinite distance is just focused on the retina.
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regulating proximal point: the closest point that the human eye can see with all its regulating ability. When the regulating ability is maximum, the light emitted from the proximal point is just focused on the retina.
adjustment amplitude the maximum adjustment force that the human eye can produce is the difference between the refractive power when looking at the far point and the near point. The closer the proximal point of
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normal eyes, the greater the adjustment ability, which indicates that the elasticity of their lens is better. Early in life, the adjustment of the human eye is great, about 15. 00D～25。 00D, which decreases gradually with the increase of age, and decreases by about 0 every year. 25D～0。 The amount of adjustment of 40d. In this way, at the age of about 40, the adjustment force of the eye is not enough to comfortably complete the close work. The elasticity of the lens decreases with age, and the proximal point becomes farther. For example, the near points of 10, 20 and 60 are 8 respectively. 8 cm, 10 cm. 4 cm and 83. 3 cm. The elderly become far away because of their proximity. They can see things far away clearly, but it is difficult to see things near. It is called presbyopia. The change of
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adjustment force will change the range that human eyes can see. The range that the human eye can see clearly through the adjustment ability between the far point of adjustment and the near point of adjustment is called the adjustment range. The adjustment range of emmetropia, myopia and hyperopia should be considered separately. Calculation of adjustment range of
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example: a 60 year old man with emmetropia had an adjustment range of 1. 00D, try to wear + 2. The range of bright vision when 50D reading glasses are used.
the longest distance you can see when wearing glasses: 1 / + 2. 50D 40 cm
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in front of the eyes. The closest distance you can see when wearing glasses: 1 / (+ 2.50 + 1.00) 28 in front of the eyes. 6cm
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the longest distance that can be seen without glasses: 1 / 0 the shortest distance that can be seen without glasses: 1 / 1. 00
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in front of the eyes. This patient is ametropia, and the adjustment amplitude is 1. 00D, after wearing corrective lenses, the far vision reached 1. 0, equipped with lower light 2. 50D。 In case of dual lens, the range of bright vision:
the maximum distance that can be seen with the added part: 1 / + 2. 50D 40 cm
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in front of your eyes. The nearest distance you can see with the added part: 1 / (+ 2.50 + 1.00) 28 in front of your eyes. 6 cm
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the longest distance that can be seen in the remote area: 1 / 0 the shortest distance that can be seen in the remote area of
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at infinity: 1 / 1. Considering the adjustment range, the 1m
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in front of the eyes can measure the clear range of presbyopia patients after matching glasses, and confirm whether they can meet the original intention of presbyopia patients after matching glasses, so as to provide more high-quality clear vision for presbyopia patients.
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from the perspective of lens form, single lens can only meet the needs of seeing close in various refractive states, and dual lens can meet the needs of seeing far and near, but can not see the needs of middle distance. Therefore, it is recommended to wear progressive lens to get good and complete vision.