Presbyopia and myopia This is because when the eyes look at near objects, it is necessary to change the refractive power through the adjustment, this adjustment function is the lens in the role of the ciliary muscle, by changing the degree of thickness, so that the focal point falls exactly on the retina to realize. With age, the lens gradually hardening, ciliary muscle function decline, this adjustment is gradually difficult and blurred near vision, and eye swelling, headache and other symptoms. This is what we often call presbyopia. In the early stage of cataract, the degree of clouding of the lens is not high, but it will change its refractive ability, mostly the convergence ability is improved, so that seeing near objects become clear in turn. Cataract is caused by temporary myopia, then presbyopia can be myopia all offset or partially offset, the elderly will feel that they can see things nearer than in the past clear, can be changed to use lower presbyopia, or even do not have to wear glasses. Cataracts The essence of cataracts is the loss of vision caused by the clouding of the lens, in which light is blocked by the cloudy lens and cannot be projected clearly on the retina, resulting in blurred vision. Cataracts are mostly seen in people over 40 years old and their incidence increases with age. Physician’s comment: Cataract first manifests itself as blurred vision, starting with a shadow in front of the eye with the eyeball rotation, progressive painless vision loss, better vision in good light, poor vision in poor light, that is, the medical contrast sensitivity loss, some patients feel that there is a monocular diplopia, and often say that you can see the round moon with a big tail, which is due to the turbidity and uneven lens makes the light through the crystal refraction, refraction, refraction, refraction, refraction, refraction, refraction, refraction of light through the lens, and refraction of light through the crystal. This is because the lens turbidity unevenly makes the refraction, diffraction and reflection of light through the crystal changes, making the object in the retina imaging changes. Secondly, there is a change in the existing presbyopia or a new myopia or astigmatism. Other, manifestations such as monocular diplopia or polymetropia, iridescence, photophobia and glare can occur because of uneven areas of lens clouding. For example, if the lens clouding is in the center of the crystal, the patient’s vision is very poor in bright light and significantly better in poor light. At this point, patients often complain that they can’t see well in sunlight, while they can see clearly in a room. Other early signs of cataracts include poor color vision when looking at colors, poor dark adaptation, and prolonged time taken to see objects clearly. In addition to age-related cataracts, there are many other causes of lens clouding, such as trauma, metabolic disorders, and various eye diseases that require vigilance, the most common of which is diabetes, which we have already covered in the relevant section. Cataract is a painless gradual loss of vision, which can be corrected by prescription lenses in the beginning, but in the later stages, as the clouding of the lens deepens, it gradually fails to transmit light, and the vision eventually decreases severely enough to require surgical treatment. At present, cataract can be regarded as a disease with relatively satisfactory surgical results, the operation time is not long, and the operation is not very painful, so cataract patients do not need to worry.