Is it true that reading in insufficient light spoils vision?

Since childhood, many have heard from parents that reading at dusk without light or with a flashlight under the blanket is harmful to the eyes. We decided to check if this is really so.

Majority Of us at least once in our lives heard Caution: "Turn on the light, otherwise you will spoil your vision!" Special Angry of parents usually Calls habit children read At night, hiding with a blanket with a blanket and highlighting with a flashlight. With the question of whether it is possible to lose vision due to reading during dim lighting, people turn to Ophthalmologists and to resources, dedicated corrections vision. Potential Harm Readings In poor lighting, materials in the media are also devoted to Blogs. Speaking about the irreversible consequences for vision, sometimes bring The example of Johann Sebastian Bach is supposedly a German composer lost vision because in his youth he copied the musical notebooks in the light of the moon.

In order to understand whether it is harmful for the eyes to read with insufficient lighting, you need to figure out how this organ works with a different amount of light. The elementary particles of light reflected from the object - photons - They get On the photosensitive cells of the retina, and they, in turn, transmit a signal to the brain through the neurons chain using electrical impulses. If the lighting is not enough, the pupil ExpandingTo get more light on the retina. If there is too much light, the pupil narrows, adjusting the flow of photons that reach the photosensitive area of ​​the eye. Such a pupil reaction - example manifestations of an unconditional reflex, it is carried out by the body “in automatic mode”, that is, it is impossible to forget to adapt the pupil to the changed level of the light. When moving from dull lighting to a bright pupil reacts Very quickly - its diameter decreases to the desired size in just a few seconds. With a reverse transition, that is, adaptation to darkness, the pupil reacts slower. With normal illumination, the pupil has a diameter of about 3 mm, in the first second after dimming it increases to 3.8 mm, after 5 seconds. - Another 2 mm. In total, the adaptation process takes up to 15 minutes, during which time the pupil reaches 7.4–8 mm in diameter. The darkening, unlike bright light, cannot cause traumatic changes. 

For expanding and narrowing the pupil Answer Muscles: for the first function - the dilator of the pupil (Musculus dilatator pupillae), and for the second - the sphincter of the pupil (Musculus sphincater pupillae). With a sharp outbreak, the spinning muscle quickly tenses, protecting the eyes, but part of the photosensitive cells still “turns off” from work for a while. If you sharply turn on the light in the dark room, then dark spots will swim in front of your eyes and, perhaps, a person will even experience unpleasant painful sensations. If in the illuminated room to sharply turn off the light, then photosensitive cells are gradually adapting to the darkness, a person will not experience any painful sensations. 

At the same time, household experience tells us that with dim lighting, the eyes should not experience additional loads. It is not in vain, when a person feels visual fatigue, he seeks to leave bright light to partial shade and give his eyes a vacation. Weak lighting is a slight stimulus of photosensitive mesh cells, due to this, muffled light allows the eyes to relax. 

Experts agree that weak illumination does not harm their eyes. The doctor and popularizer of evidence -based medicine Andrei Sazonov speaksthat “lighting can be sufficient and insufficient. With sufficient, we are able to read and write, and with insufficient - incapable. In other words, any lighting in which reading and writing is possible is considered suitable. ” He also draws an interesting parallel: “To say that reading in weak light is harmful to vision is like saying that listening to quiet music is harmful to hearing.” Foreign experts are also expressed in a similar way. American ophthalmologist Richard Rosen calls This belief by the myth compares the lens system in our eye with the camera: "We do not think that if we take pictures in weak light, we will damage the camera." Harvard Medical School specialists also Reportthat this is a myth. In fact, there is no “insufficient” lighting for reading-if there is not enough light, the eye is not able to distinguish the letters, if the eye can still distinguish the letters, then there is enough light for reading. 

Doctors note that in dim lighting, focusing on the text can be more difficult. By words Andrei Sazonova, less intensity of lighting reduces comfort and reading speed, and Dr. Rosen Turns Attention to the fact that with bright lighting, the depth of sharpness is greater, therefore, we can consider more small details. Also ophthalmologists Markthat reading in reduced light can lead to faster eye fatigue, and some people have such a stress Maybe Even provoke a headache. Therefore, it is important to listen to your sensations and, if discomfort occurs, increase the brightness of light or postpone reading to a more suitable situation.

Moreover, by law installed Lighting standards for workplaces of various specialists and for training in schools. This indicator indicates what intensity of lighting training or work will be most effective, that is, people who are there will not have to strain too much. However, the document does not say that a decrease in this indicator will have a harmful effect on the organs of vision. 

Thus, reading in dull lighting, contrary to the warnings of our parents, cannot worsen vision. It is best to focus on subjective sensations and, feeling fatigue, let your eyes rest. At the same time, reading under a covers with a flashlight cannot be called safe. Although low illumination does not worsen vision, but too small the distance from the eyes to the book can really lead to problems. Optimal The distance from the face to the book is 35–40 cm, so that, covered with a blanket with his head and highlighting with a flashlight, it will be extremely difficult to observe it. 

Image on the cover: PEXELS

Not true

What do our verdicts mean?

Read on the topic:

1. Is it true that reading is harmful to vision? 
2. Is it true that sitting close to the TV is harmful to health? 
3. Is it true that reading from the screen spoils vision?