A comprehensive explanation of myopia and aging

Abstract: the normal eyeball is generally a positive ball. The back wall of the eyeball has a layer of retina that can feel light, and there is a lenticular lens in front of it. When looking at things near, due to the forced contraction of the ciliary muscle of the eye, the lens will become convex due to its own elasticity, and the refractive index will increase accordingly.

many people think that people with myopia are not old. In fact, this statement is wrong. Because people with myopia, like others, have a series of aging and degeneration phenomena in their eyes with the growth of age. The first is that the nucleus of the lens gradually increases and hardens, and the elasticity of the crystal becomes smaller and smaller. The second is that the muscle strength of the ciliary muscle gradually weakens. Therefore, when looking at the nearby target, it lacks the necessary adjustment power and has difficulty in reading and writing. This is presbyopia, commonly known as presbyopia.

however, the performance of people with myopia after presbyopia is different from that of people with normal emmetropia, so the degree of glasses required is also different. Generally, people with emmetropia begin to grow old after the age of 40. At the age of 45, it is about + 1.00 – + 1.50D, at the age of 50, it is about + 2.00d, and at the age of 55, 60 and 70, it is about + 2.50d, + 3.00ds and + 4.00d respectively. However, the number of glasses needed by people with myopia after the occurrence of aging depends on their original myopia and their specific age. For example, a person with myopia-3.00d, no matter how old he is, as long as his myopia remains the same, he will always wear his original myopia glasses in the distance. However, with the increase of age, after the age of 40, the degree of glasses he needs when reading, writing or doing close-up fine work is constantly changing. For example, when he reaches the age of 50, his eyes also have + 2.00 old flowers. Then, the degree of glasses he wears when looking close should be -1.00 ((- 3.00d) + (+ 2.00) = – 1.00d), that is, myopia -1.00d. Similarly, when he reaches the age of 60 and 70, the glasses he wears when looking close should be zero (local light) and + 1.00d respectively.

and

so we often see in real life that the elderly wearing the original myopia glasses often need to take off the myopia glasses when reading and writing. Even if others take off their glasses, it is still inappropriate to look close, and they still need to move the target closer or farther. All these are actually caused by different degrees of aging on the basis of myopia.

in this way, we come to a conclusion that the degree of glasses a nearsighted person should wear when he has presbyopia should be the algebraic sum of his original degree of myopia and the degree of presbyopia at that age, and the degree after the two offset is the degree of glasses he should wear when he looks near. However, when we match presbyopic glasses for myopia, it can’t be so simple. It is also necessary to take into account the specific conditions of the individual wearer’s personal physique, nutrition, working environment, professional requirements and personal habits, and then after full trial wearing, finally fit the glasses in a specific degree, so as to match a pair of suitable presbyopia glasses for the myopia.

the normal eyeball is generally a positive ball. The back wall of the eyeball has a layer of retina that can feel light, and there is a lenticular lens in front of it. When looking at things near, due to the forced contraction of the ciliary muscle of the eye, the lens will become convex due to its own elasticity, and the refractive index will increase accordingly. On the contrary, if you look at something far away, relax the ciliary muscle and flatten the lens. The eye adjusts the focal length in this way, so that the focus of different objects and images can just fall on the retina.

in myopia, the anterior posterior diameter of the eyeball is longer than that of the normal eyeball. When looking at things in the distance, although the ciliary muscles have been completely relaxed, the crystalline Hugh has been pulled to the most flat level, and the focus of the object image can only fall in front of the retina. What reaches the retina is an open hazy circle, so what the eyes see is only a fuzzy image. Myopia is mostly formed in adolescence between teenagers and twenties, because the eyeball is developing rapidly, unstable and not stereotyped. Therefore, bad eye habits can cause eye deformity, just as bad sitting posture can cause hunchback. However, their eyes are still young and energetic. As long as they wear a pair of concave lenses of appropriate degree, they can still normally use the adjustment ability of ciliary muscle and lens to see far or near like normal eyes.

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when the eyes are old, although the length of the ocular axis is normal, due to aging, the contractility of ciliary muscle and the elasticity of lens are reduced. In other words, the eye lens can only maintain a relatively flat state and has no ability to adjust it to a convex point. Therefore, when you look at things near you, the object image focus always falls behind the retina, and what is on the retina is only a hazy circle that has not gathered into focus. Although you can also wear a pair of presbyopic glasses (convex lens) to correct at this time, the elderly are different from the young people after all. After wearing glasses, the young people can make full use of their adjustment ability to see far and near. The elderly must take off the presbyopic glasses when looking far. This situation is particularly evident in the elderly who have become myopic when they are young: they often have two pairs of glasses in their pockets. One pair is for close viewing because he is old; The other pair is used to see far, because his eye axis is still so long and is still myopia.