What are reading glasses?
Reading glasses is a type of optical product that belongs to a convex lens. Reading glasses are mainly to meet the needs of people with presbyopia. And they’re used to supplement vision for middle-aged and elderly people. The use of reading glasses has played an indispensable role in improving people’s quality of life.
Presbyopia is a normal physiological phenomenon, not an eye disease, nor is it unique to the elderly. After the age of 40, as the lens of the human eye gradually hardens, the ciliary muscle gradually becomes paralyzed, so the human eye cannot effectively adjust the shape of the eyeball, and can only see near objects by adjusting the distance between the eye and the object. If you find that you can only see clearly by moving objects far away, then you may have presbyopia.
Types of reading glasses
There are three types of reading glasses on the market, single-vision, bifocals, and (ADD)progressive.
- The single-vision lens can only be used to see near, and you need to take off the glasses when looking far.
- Bifocals mean that the upper half of the lens is used to see far away, and the lower half of the lens is used to see near. But bifocals have a design with visible lines between visionswhich is not good-looking.
- Progressive（ADD) lenses can meet the needs of viewing objects at different distances from far, middle and near, and their appearance is also very good since they don’t have visible lines. The penetration rate of progressive glasses has been increasing year by year.
Why avoid choosing big frames for reading glasses?
- The lens molds of reading glasses are smaller than that of myopia. The maximum value of mold for myopia can reach 90mm, while that of presbyopia can only reach 80mm.
- The PD number used by presbyopia is Near PD normally, which is smaller than Far PD used by myopia. If you choose a big frame to make your reading lenses, your PD number can’t be put into the best position because your Near PD is too small to be used in a big frame. In this way, your reading glasses would be blurred and unclear. So we recommend you choose medium size glasses to make reading glasses.
