I don't know how many people find that their parents don't know when wrinkles appear on their faces, and even reading glasses, what is even more shocking is that many of their reading glasses are purchased from vegetable markets, stalls, and night markets.
Think about the time when they used to ask us about the profession in order to correct our vision with myopia glasses, optometry and lenses, but now they choose reading glasses for themselves so casually, I can't help but feel sad in my heart, and at the same time, I will also wonder, is it really okay to wear such glasses?
桌子上的书Books on a table
The technical term for presbyopia is presbyopia, a normal physiological phenomenon. As we age, the lens in the eye gradually hardens, and the adjustment ability of the eye gradually decreases, which will lead to the inability to focus clearly when looking near, and the sight will be naturally blurred, and the degree of presbyopia will continue to increase with age.
Generally, the presbyopia phenomenon of emmetropia will appear around 40~45 years old, and the incidence rate at the age of 52 is almost 100%, and the time of presbyopia in people with refractive error will be slightly sooner or later, such as the "myopia immortality" that many people think is actually only a matter of time, and people with farsightedness may appear before the age of 40 at the earliest.
Can I buy reading glasses from a stall?
To put it simply, it is possible to meet the relevant national standards, but it is not recommended.
The main reasons are as follows:
First of all, don't think that reading glasses are cheap and there are no quality requirements, the current market sales of presbyopia finished glasses are in line with the relevant national standards, some companies implement the standard of GB13511.1-2011 single light and multifocal glasses, and some companies implement the GB13511.3-2019 single light presbyopia standard, you must know that meeting the national standard is the basic guarantee of a product, and many stall night market sales of reading glasses do not even have this guarantee, so there will be quality problems in many aspects.
Secondly, even if the reading glasses sold in night market stalls or even online meet the above national standards, they are unable to provide optometry services due to the restrictions on sales venues, so they can usually only use empirical methods to help buyers choose glasses.
An example of a more common empirical lens selection icon
However, the above table is only for the experience of people with emmetropic eyes, and a large part of the population, their visual acuity may reach 1.0, but it does not mean that they are all emmetropia, many people may have some basic degrees to a greater or lesser extent, such as small hyperopia, low myopia, 50 In the case of astigmatism or myopia in the left eye and myopia in the right eye, you may be able to see clearly without glasses when you see far, but when you need to wear reading glasses, you need to add a near to their basic diopter, which needs to be adjusted according to the needs of the eyes.
In this way, the empirical method will actually cause a large error, and the wrong power may not be reflected when you first wear it, but after wearing it for a long time, it will lead to eye fatigue, dizziness and nausea, and even the more you wear it, the more you wear it, the more you dazzle it. Therefore, the empirical method can only be used as a reference when the conditions do not allow it and it is a last resort, and if the conditions allow, it is recommended to go to a formal institution for examination and glasses.
How should presbyopia be properly fitted?
To put it simply, even reading glasses need to be professionally fitted.
The fitting of presbyopia seems to be very simple, but from a professional point of view, the fitting of presbyopia is actually more complicated than other refractive errors.
As mentioned above, although many people's eyesight is not bad and does not affect their daily eyes, there is a certain degree of refractive error in their eyes, so for this kind of people, if they want to get the correct presbyopia correction power, they must first measure their basal power, and then perform additional photometric measurement of presbyopia.
For the majority of us who already wear glasses, the process is even more so, and unlike the general impression of presbyopia, convex lenses are used, when myopia exceeds a certain degree, even reading glasses are used for concave lenses for myopia. For example, if you are -500 degree myopic and have presbyopia +100 degrees, then you need reading glasses with a power of -500+100=-400, instead of buying +100 degree reading glasses. By analogy, farsightedness and astigmatism also need to add this near additional luminosity to the original power, which is the final near presbyopia luminosity.
And some special groups, such as monocular refractive error, one eye myopia, one eye emmetropia, one eye myopia and one farsightedness, or one eye simple astigmatism, one eye myopia, etc., need to be accurately measured to ensure the accurate fitting of reading glasses.
In addition to the optometry power, when processing, it is also necessary to re-measure the interpupillary distance of the near eye, this is because when we see near, our human eyes will have an inward rotation, so the interpupillary distance is reduced compared with the far, inferred from the empirical method is about 2mm, but in fact, because each person's eye rotation ability is different, there is naturally a difference in the near interpupillary distance, and only measurement can ensure accuracy.
And with the increase of age, many diseases will also cause vision loss in the elderly, so before fitting, professional stores will also check whether there is a possibility of vision loss caused by eye diseases, such as cataract, glaucoma, macular degeneration, etc., through slit lamps or ophthalmoscopes.
It can be seen that the fitting of presbyopia is more complex and necessary.
How do I choose lenses after fitting?
After reading the above content, I believe you have understood that if you want to match a pair of glasses that suits you, you need to meet certain conditions. In fact, except for a small number, the vast majority of other presbyopia people need professional fitting customization, that is, like other people with refractive errors, they choose the right lens frame according to the prescription for processing.
And now according to different needs, in addition to single vision lenses, progressive multifocal lenses are a better type of presbyopia solution for the majority of people who wear glasses, which realizes multiple focal points on a pair of lenses, and can meet the needs of eyes at different distances at far, medium and near at the same time. It eliminates the trouble of looking at two pairs of glasses from afar or near, or taking off reading glasses back and forth.
After reading the above, remember to accompany your parents for a professional vision examination and equip them with a suitable pair of reading glasses when you go home next time.
bibliography
[1] Ni Hailong, Wang Qinmei. Research progress on the mechanism and treatment of presbyopia[J]. Chinese Journal of Optometry and Visual Science, 2000, 02(002):123-125.
[2] Liu Hongjun, Xu Yajuan, Xu Lin, et al.National Standard GB13511.1—2011 "Fitting Glasses Part 1: Single Light and Multifocal" Part of the Technical Indicators Interpretation[J].China Journal of Optical Science and Technology, 2012(9):2.
[3] GB/T 13511.3-2019
[4] Mei Ying, Tang Zhiping. Optometry Clinic Optometrist Handbook.2019.
[5] Qu Jia.Opticology.People's Medical Publishing House.2019.
[6] Yang Zhikuan. Clinical optometry[M]. Science Press, 2008.
[7] Liu Yali. Factors influencing the adaptation speed of progressive films[J]. Chinese Journal of Optical Science and Technology, 2007.
[8] Liu Yang. Progressive film fitting experience for middle-aged and elderly people[J]. China Journal of Optical Science and Technology, 2016(5):4.
[9] Dong Zhenzong. Practical fitting skills for progressive multifocal lenses for middle-aged and elderly people[J]. Chinese Journal of Optical Science and Technology, 2022(1):2.
Planning and production
Source | Popular Science China
Author丨Jin Xin, Director of Huainan Shouyang Institute of Myopia, Strabismus and Amblyopia Prevention and Control
Audit丨You Yuxia, Deputy Chief Physician of Beijing Aier Xinli Ophthalmology, MD