Why is 40 a threshold for presbyopia?

Audit expert: Liu Dongbao

Chief Physician of the Ophthalmology Department of the Shenyang Red Cross Hospital: Presbyopia is undoubtedly a synonym for aging in the eyes of many people. Some people regard it as a scourge and fall into anxiety about aging after suffering from it; others think that they are still young and energetic and have nothing to do with presbyopia. However, in fact, presbyopia may appear after we are 40 years old, and it is much closer to us than everyone thinks.

Presbyopia is a normal physiological aging phenomenon that occurs in everyone at a certain age. It is mainly manifested by difficulty seeing close objects clearly, and usually requires the target to be farther away to see clearly. This symptom becomes more and more obvious as age increases.

Source: hippoppx

There are many factors that affect presbyopia. In addition to each person's genetic differences, there are also refractive errors, physical fitness, geographical location, climatic conditions, and one's own vision. These factors will affect the early or late onset and severity of presbyopia symptoms.

Why do eyes become presbyopic?

Under normal circumstances, after light enters the eyeball, it will first pass through the cornea and lens , where the light is refracted, then pass through the vitreous body , and finally focus on the retina . The electrical signal is then transmitted along the optic nerve to the brain. After being processed by the brain, we can see things clearly.

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In the process of processing light, the lens plays a major focusing role. When looking at distant objects, the ciliary muscle relaxes, stretching the lens into a flat shape, which reduces the refractive power of the eyeball; when looking at close objects, the ciliary muscle contracts, the lens becomes convex, and the refractive power of the eyeball increases.

However, as we age, especially after the age of 40, the sensitivity of the retina and color vision will gradually deteriorate , the contraction ability of the ciliary muscle will gradually decrease, and the elasticity of the lens will gradually weaken. These will cause our eyes to have a decreased ability to adjust when observing close objects, and we will no longer be able to focus smoothly on far and near objects, which means we can't see things clearly and develop symptoms of presbyopia. This is why our eyesight gets worse after the age of 40.

Source: hippoppx

Generally speaking, the cells in the retina of the human eye begin to age around the age of 40, and this aging is caused to a certain extent by the decline of mitochondria, which produce energy and enhance cell function. Among the structures in our eyes, the mitochondria in the retinal photoreceptor cells have the highest density, which means that they need a lot of energy in their daily work. As the energy supply of mitochondria in the cells gradually decreases, the photoreceptors lack energy and cannot function properly, so the retina will age faster than other organs.

Can red light treat presbyopia?

Recently, a study on the retina has attracted people's attention. According to reports, a study published by scientists from University College London in the United Kingdom in "Scientific Reports" pointed out that red light is quite helpful in improving our vision and delaying the aging of vision. Exposing the eyes to deep red light once a week on average can slow down the natural decline of vision.

Reading glasses have a magnifying effect Source: wiki

Scientists conducted a small clinical trial in which they invited 24 volunteers aged between 28 and 72 who had no eye-related diseases and asked them to watch a specific LED flashlight with a wavelength of 670 nanometers for 3 to 5 minutes every day. The experiment lasted for two weeks.

By comparing the sensitivity of the photoreceptor cells on the retina before and after the experiment, the researchers found that this wavelength of deep red light had no significant effect on young subjects, and their photoreceptor cells basically maintained their activity and normal function before the experiment; but for people around 40 years old and above, the effect of deep red light was very obvious, and the sensitivity of the cone cells of some people even increased by nearly 20%, greatly improving their perception and discrimination ability of strong light and color.

Source: News Photo

In this regard, the researchers said that it may be because deep red light with a wavelength range of 650nm-100nm can improve the performance of mitochondria and increase energy output in cells, thereby improving the function of cone cells. Since there is still a lack of deep red light ophthalmic treatments acceptable to ordinary people, scientists believe that the success of this study will undoubtedly indicate that family ophthalmology treatments will become easier and will help millions of people with impaired vision around the world in the future.

Of course, current research results show that the initial conclusion that "red light can improve vision" only applies to middle-aged and elderly people, and has little effect on young people. This may be because young people have more active cell metabolism and stronger mitochondrial function, so they do not need external red light stimulation to increase cell energy supply.

Seeing this, some friends may ask, can an experiment involving 24 people explain the problem? Admittedly, this experiment was small-scale and only a preliminary judgment, but as scientists continue to conduct in-depth research, there will definitely be further breakthroughs in the future. But for now, don't shine your eyes in red light for no reason. Whether there are certain risks remains to be studied. Don't damage your eyesight instead of improving it.

In addition, due to the development of relevant research, there are now many related "red light eye therapy devices" on the market, which are said to be able to improve vision. The editor would like to remind everyone here that you should consider carefully before purchasing related products.