The majority of people in the 40 to 45-year-old will quietly appear see thing difficultly, at first they can not look at a small writing thing, we must move books, newspapers a little far away, then we can see more clear.
In fact, this is a normal physiological phenomenon of human body, it is the body signals of the beginning of aging. With age, lens of the eye gradually hardening, thickening, and the ability to regulate the eye muscles also will be diminished, resulting in reduced ability to zoom.
Therefore, when we look at close objects, the image that projects on the retina can not be completely focused, when look at close objects our eyes will be blurred. Even if you take good eye protection, the degree of presbyopia will increase with age, generally in accordance with 50 degrees every five years to enhance the speed of increase. According to age and eyes, presbyopia degree of correspondence tables, most of their own eyes and refraction in good condition, that is, no myopia, hyperopia people, the age of 45 eyes of presbyopia degree is usually 100 degrees, 55 to 200 degrees, to 60 year-old, degrees will be increased to 250 degrees to 300 degrees, then took degrees in general is no longer the old eyes deepened.
Presbyopia is often treated as a sign of old age, many people refuse to agree with the old and they do not wear reading glasses to correct vision, this may instead increase the burden on the eyes. If you do not wear reading glasses, even if we manage to see goals clear, it will also be due to forced regulation, excessive ciliary muscle contraction, resulting in all kinds of eye fatigue phenomena, such as tight eyebrow, eye pain, blurred vision and other symptoms of eye fatigue.
Wear reading glasses are also very demanding, we must be get our glasses prescription accurately, and every five years, we have to re exam our eyes, we can not wear wrong glasses,if needed, we have to buy new prescription glasses. Modern reading glasses use more progressive lenses, lenses were divided into three sections, the top to look too far matter (polishing zone), below the position to see at close range (near light zone), the middle part (in the light area) is used to fancy the distance objects, between the three light zones will be presented with the degree and depth of incremental change, and thus adjust the distance to see a variety of objects.