Do you know the simple calculation method of reading glasses?

Presbyopic glasses are used by most elderly people to assist vision. However, many old people are not so clear about the concept of reading glasses' degree, and do not know when to match with what kind of reading glasses.

So today, we will bring you an introduction to the calculation method of reading glasses. Let's learn together.

 No.1 Calculation method of reading glassesReading glasses have degrees. The degree of reading glasses will increase with age. Generally, the degree of eyes will not change much after the age of 60.

The degree changes regularly. Generally, it increases by 50 degrees every five years. In the case of good eyes, it is generally 100 degrees at the age of 45, 200 degrees at the age of 55, and 250 to 300 degrees at the age of 60. In the future, the degree of glasses will not deepen. So how should the degree be calculated?

No.2 equipment used: scale, cardboard, sunlight

Operation steps:

1. Make the reading glasses vertical to the mirror, and put the cardboard on the other side.

2. Repeatedly adjust the distance between the paperboard and the mirror until the smallest bright spot appears on the paperboard.

3. Measure the distance f (in meters) from the bright spot to the center of the mirror with a scale. Is its focal length.

4. The degree of reading glasses is equal to the reciprocal of its focal length multiplied by 100 to calculate the degree of reading glasses.


No.3 presbyopia degree is related to age

For example, at the age of 45, the old flower is +1.50d (i.e. 150 degrees). At the age of 50, whether you wear glasses or not, the old flower will increase to +2.00d (i.e. 200 degrees).


There are old flowers. If you insist on not wearing reading glasses, your ciliary muscles will be exhausted and unable to adjust. It will certainly aggravate reading difficulties, produce dizziness, eye swelling and other symptoms, and affect your life and work. This is very unwise.


Therefore, presbyopia glasses should be equipped immediately without delay. As you grow older, the reading glasses you used to wear are not enough and should be replaced in time.



If the elderly want to wear progressive lenses, they should choose carefully. Once you feel that the reading glasses are not suitable for your own degree, you should replace them immediately. If you wear glasses with improper degree for a long time, it will not only bring a lot of inconvenience to the life of the elderly, but also accelerate the aging speed of the eyes of the elderly.


And when you find yourself with presbyopia, don't put on presbyopia glasses immediately. The elderly should take advantage of their ability to adjust their eyesight and give their eyes enough opportunities to exercise.


Post time: Jun-20-2022