What Should I Consider When Buying Reading Glasses?

Reading glasses, also called presbyopic glasses, are a class of optical products. The glasses used by people with presbyopia eyes belong to a convex lens. Reading glasses are mainly to meet the needs of the eye-presbyopia crowd.

[lo hu jìng]

Reading glasses, also known as reading glasses, are a class of optical products for those with presbyopia eyes.

There are three main types of reading glasses on the market, namely single-lens, double-lens and progressive multifocal lenses. The single-lens lens can only be used to look close. You need to take off your glasses when looking far. The bifocal lens means that the upper half lens is used to see far, and the lower half lens is used to see close, but this reading glasses has a phenomenon of jumping, and the appearance is not beautiful. Progressive multifocal lenses can meet the needs of different distances, distances, and distances, and the appearance is also very good. The penetration rate has increased year by year in 2019, and the first generation has a longer adaptation time.

Presbyopia is a normal physiological phenomenon

Interpupillary distance of reading glasses

For the first time wearing a reading glasses, you need to know about the near-PD (interpupillary distance). Due to the collective action of the human eye when near vision, the visual axis rotates inward, so that the near-interpupillary distance (using a reading distance of 33cm as an example) is better than the far distance ( Looking up) PD is 4-6mm smaller. Reading glasses have an important optical index, OCD (horizontal distance between the optical centers of the two lenses). The OCD and near-PD should be as consistent as possible. The national standard stipulates that there is a difference range between the two. The sunset red reading glasses have a tolerance of ± 3mm according to the relevant national standards. That is to say, if a customer who uses PD = 62mm recently, the OCD value of the reading glasses can be 59-65mm. between. However, the best solution is to choose glasses with an OCD value smaller than the interpupillary distance. Wearing glasses with an OCD value that is much larger than the interpupillary distance will cause guests' eyes to be sore, easily fatigued, and unable to concentrate their vision. If the interpupillary distance of the guests is too small and too large to make the choice of the mirror, and the optics cannot be assembled (no oversized frame, oversized film), the focus-free reading glasses are the best choice.

Reading glasses using distance

Presbyopia is characterized by the poor ability of the eyes to see far and near. For example, when the user's visual acuity is + 4.00D (commonly known as 400 degrees), his vision adjustment ability can only work within a few centimeters. A pair of reading glasses only adds a fixed diopter to the user's visual acuity, and Does not enhance the user's vision regulation. That is to say, the user is not fixed to wear a certain reading power of a fixed power, but should select a reading power of a suitable power according to the distance of using his own vision. For example, when reading a book, reading a newspaper, or writing, the use distance is 33cm, which is called the reading distance. At this time, the age of the user is proportional to the power of the reading glasses: (see the table below)

age	40	45	50	55	60	65	70
Presbyopic power	+ 0.75D	+ 1.50D	+ 2.00D	+ 2.50D	+ 3.00D	+ 3.50D	+ 4.00D

However, if you are watching TV, the distance between the human eye and the TV screen is generally 2.50 meters. At this time, the age of the user and the power ratio of the reading glasses become the following table:

age	40	45	50	55	60	65	70
Presbyopic power	No need to	No need to	No need to	No need to	No need to	+ 1.00D	+ 1.50D

Modern people's eyes involve more and more aspects, and the distance and objects of middle-aged and elderly people's use of vision in the near and middle distances have also greatly expanded. In the past, near-sightedness optometry glasses could not meet consumer needs.

Use of vision	Read and write	computer	housework	shopping	watch TV
Use vision distance	33cm	50cm	80cm	120cm	250cm

Therefore, when selecting reading glasses, you should choose the reading glasses that are suitable for you according to your own habits and needs, such as the distance at which you use the reading glasses.

Reading glasses secondary spare

Under normal circumstances, from the age of 55, the naked eye (without glasses) can see the distance more than 0.86 meters, and if you read + 2.50D (250 degrees) reading glasses can see the distance is about 0.27-0.40 meters . In this way, a blind spot appears at a distance of 0.5-0.7 meters, and this distance is exactly the second most commonly used distance for guests (doing housework, shopping, using a computer ...). Therefore, without supplementing the secondary vision of this blind zone, the eyes of the guests are in the blind zone distance. No matter the naked eye or the reading reading glasses, they will often be in a fatigue state, which will accelerate the development of presbyopia. If you need reading glasses with a reading distance of + 2.50D (ie 250 degrees) or more, for your own needs and vision health, prepare a pair of reading glasses for yourself at a long distance (about 70cm), that is, Buy a pair of reading glasses that are + 1.50D (150 degrees) lower than the reading glasses that are suitable for reading. Users of reading glasses in foreign countries are not distracted from their eyes. According to the needs of use, several reading glasses with different powers are used alternately. Glasses sold abroad are also sold with several reading glasses with different powers. However, the reading glasses in China are bad. Under the age of 60, I wear it to + 4.00D (400 degrees), which deepens the presbyopia and affects the health of vision.

Reading glasses precautions

1. You can wear glasses without dazzling, don't delay.
2. A comprehensive inspection and optometry should be performed on the eyes before the optician.
3. Try it on for a while after the mirror is fitted.
4, to distinguish between occasions to wear. Reading glasses are only suitable for looking at objects at a short distance, and should not be worn when looking at distant or normal things. It is advisable to wear reading glasses for a long time regardless of time, which will cause dizziness, unclear vision, and decreased eye conditioning.
5, reading glasses should not be worn to the end.