It is a physiological phenomenon, not a pathological condition or a refractive error, and is an inevitable visual problem that occurs when people reach middle and old age. As people age, the ability of the eye to adjust gradually decreases, resulting in difficulty in seeing close to the eye and the need to add a convex lens in addition to its static refractive correction in order to have clear near vision, a phenomenon known as presbyopia. The onset and progression of presbyopia is directly related to age and occurs mostly after 45 years of age. The results of Duane’s adjustment measurements on 4,000 human eyes clearly show that the adjustment power in adolescents is 14.0 D, with the near point at 7 cm. By the age of 60, only about 1.0 D of regulation was maintained Table 1 shows the normal values of regulation (D) at different ages. Most near working distances are between 28 and 30 cm. orthoptic eyes have only 3.5 to 4.0 D of accommodation by age 45. this degree of accommodation has reached the limit of seeing near objects clearly. in this case, if one needs to do near work continuously, one has to use up all of the accommodation to get the usual vision. The eye has to work intensely in order to maintain close vision, and the constant tension is bound to cause visual fatigue. Generally speaking, when using regulation, presbyopia can only use 2/3 of the total regulation power, and the other 1/3 is reserved power to work comfortably as mentioned before. In order to insist on working at close distances, presbyopic eyes should wear convex lenses to help. When a hyperopic eye is young, its near point is much farther away than an orthoptic eye, so the symptoms of presbyopia appear earlier. On the other hand, a 4.0D nearsighted eye, because its far point is at 25cm, can use its far point as a near point to engage in close work when it is old, so although this eye is old-sighted, it does not show symptoms of presbyopia. Although the lens of the human eye hardens regularly with age, the appearance of symptoms of presbyopia depends not only on age, but also on refractive state, and changes with individual differences, habits, working conditions and lighting conditions. People who are accustomed to reading books on their lap have a later onset of self-conscious symptoms than those who are accustomed to working at close range. For example, carpenters, bookkeepers and musicians are accustomed to working at a distance of 30cm; while workers such as watch repairers and sewing and engraving workers, although of the same age and refractive state, will experience symptoms of presbyopia earlier due to the closer working distance. Furthermore, if the ciliary body is in a weakened or pathological state, physiological regulation can also be impaired. In summary, the age of onset of presbyopia symptoms cannot be determined as an absolute number and its management should be considered in a comprehensive manner according to various conditions. Clinical manifestations The discomfort of presbyopes varies from person to person, as it is related to the individual’s basic refractive state, eye habits, occupation and hobbies. For example, the subjective sensation of presbyopia is much more intense in a person who is engaged in close up fine work than in a traffic policeman whose main task is to see distant vehicles and traffic lights. Difficulty seeing close Patients will gradually find that they cannot read small print clearly at their usual accustomed working distance. In contrast to myopic patients, patients will unconsciously tilt their heads back or bring books and newspapers further away to read the words clearly, and the required reading distance increases with age. Reading requires greater illumination At first, reading at night is somewhat uncomfortable because the light is dimmer at night. Insufficient illumination not only raises the visual discrimination threshold but also dilates the pupil, which forms a large diffusion circle in the retina and makes the symptoms of presbyopia more pronounced. As we age, even in the daytime close work is easy to fatigue, so people with presbyopia, reading at night like to use brighter lights. Sometimes the light is placed in the middle of the book and the eye, which not only increases the contrast between the book and the text, but also makes the pupil narrow. But the light in front of the eye is bound to cause glare interference, the closer the light source of this interference to the visual axis, the greater the impact on vision some elderly people like to read in the sun, that is the reason. The near vision can not last Adjustment is not enough is the near point gradually become far, after efforts can also see clearly near objects. If this effort exceeds the limits of the ciliary body tension, and then look at distant objects, because the ciliary body tension can not immediately relax, thus forming temporary myopia. When looking at near objects again, there is a short period of blurring, which is a sign of a slow adjustment response. Fatigue occurs when the ciliary muscle is nearing its functional limit and cannot keep working. Because of the hypoacusis, the patient has to work at close range near the limit of accommodation of both eyes, so it cannot last. At the same time, due to the linkage effect of regulation collection, over-regulation will cause excessive collection, which is also a factor that produces discomfort, so reading newspapers is easy to serially double the handwriting, and finally unable to read. Some patients may even experience visual fatigue symptoms such as eye swelling, tearing headache, and eye itching. Diagnosis Based on the test results of hyperopia and combined with the patient’s age and clinical presentation, the diagnosis can be made. Treatment The correction of presbyopia is still done by wearing presbyopic lenses, which use the power of convex lenses instead of adjustment to move the near point to within the customary working distance.