Presbyopia, that is, presbyopia, the symptoms of the near vision can not last, the lack of regulation is the near point gradually become distant, after efforts can also be seen clearly near objects. The etiology of presbyopia is mainly as follows: 1. Age and regulation The essence of presbyopia is the diminishing regulation of the eye, and age is one of the most important factors affecting the regulation power, which is the increase of the refractive power of the eye through the shaping and convexity of the crystal. The lens increases in size throughout life as the epithelial cells in the equatorial zone continue to form new fibers, add new cortex to the sides of the lens, and squeeze the old fibers toward the nucleus. Thus, with increasing age, the crystal gradually increases in density and decreases in elasticity. The shaping and convexity of the lens is mediated through the lens capsule (mainly the anterior capsule), and the elasticity of the capsule also decreases gradually with age. At the same time, as we age, the ciliary body becomes hypertrophied due to the slow accumulation of fibrous tissue, and the crystal gradually increases in size. Although there is no known age-related change in the crystal ligament, the proximity of the ciliary body and crystal to each other must affect the tension of the crystal ligament. Other factors associated with the appearance of presbyopia Presbyopia occurs due to inadequate regulation, and the time of onset of presbyopia can be early or late, and varies from person to person, depending on the magnitude of regulation that each person has as described above. People feel comfortable and can keep gazing when the adjustment force they use is less than half of their adjustment range, and if the required adjustment force is more than half of the adjustment range, they are prone to develop presbyopia.