When going to the cinema in broad daylight, one often finds it difficult to see the steps and seat numbers clearly, leading to reduced vision. But after a period of time, vision returned to normal.
Many people think this is’ night blindness’, but in fact it is not. This visual phenomenon is called ‘dark adaptation’, which refers to the process in which the visual sensitivity gradually increases when entering a dark place from strong light or when the lighting suddenly stops, allowing it to distinguish surrounding objects. And the dark adaptation ability of patients with night blindness is much lower than the normal level!
Because at night or in dimly lit environments, it is almost impossible to see clearly, and in severe cases, it is no different from being blind! At night, one can only smear and walk, and even find it difficult to move, let alone drive …..
What is night blindness?
Night blindness, commonly known as “bird blindness”, is mainly characterized by unclear or completely invisible vision and difficulty in movement at night or in dimly lit environments. Night blindness is mostly caused by a lack of vitamin A, and may also be due to congenital or pathological conditions, but it is relatively rare.
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The retina in the human eye mainly consists of cone cells and rod cells. Rod cells work in dark environments and contain a substance called rhodopsin, which is extremely sensitive to weak light. If there is a lack of vitamin A in the diet or if certain digestive system diseases affect the absorption of vitamin A, it may cause retinal rod cells to lack the raw materials for synthesizing rhodopsin, resulting in night blindness.
This type of night blindness is also known as “temporary night blindness”. Under normal circumstances, as long as vitamin A is appropriately supplemented, it can be relieved or cured.
There is also a type of night blindness that is congenital and often caused by genetics, such as primary retinitis pigmentosa, underdeveloped rod cells, and loss of the ability to synthesize rhodopsin, resulting in night blindness. There are three major diseases: night blindness, narrow vision, and retinal pigmentation.
Primary retinitis pigmentosa is a progressive, hereditary, and malnutrition degenerative disease characterized by chronic progressive visual field defects, night blindness, pigmentary retinopathy, and abnormal electroretinogram, which may ultimately lead to severe visual field defects and vision decline.
The problem of primary retinitis pigmentosa is quite tricky, and there is currently no effective treatment method.
Moreover, primary retinitis pigmentosa is a genetic disorder, so Xi Xiaoma suggests that couples with primary retinitis pigmentosa should undergo genetic testing before preparing for pregnancy if they want to have their next generation. At the same time, it is also necessary to conduct corresponding genetic screening for the next generation who do not have symptoms of the disease, in order to prevent and treat it in advance.
Dietary prevention is very important!
Lack of vitamin A can cause night blindness, so it is helpful to consume foods rich in vitamin A in daily life to prevent and treat night blindness.
In daily life, it is recommended to do the following four things:
- Pay attention to a balanced diet and consume more foods containing vitamin A, such as animal organs, cod liver oil, etc.
- Moderate exercise, increase outdoor activities such as running, Tai Chi, etc., to expose the body to more sunlight.
- Maintain eye hygiene by not rubbing your eyes with your hands and keeping them clean.
- Do not overuse your eyes. It is recommended not to use mobile phones, computers, etc. for a long time. Prolonged use can easily lead to eye fatigue.
Vitamin A mainly comes from animal based foods, such as the liver, egg yolks, and dairy products of various animals, which are rich in vitamin A.
However, excessive intake of vitamin A is not allowed! The recommended amount of vitamin A for adults is 800 micrograms of retinol equivalent for males and 700 micrograms of retinol equivalent for females. Special reminder for friends who use their eyes too much, especially those who watch TV or use the computer for a long time at night, to pay attention. The amount of vitamin A consumed by eye use at night is higher than that during the day. If you do not pay attention to taking vitamin A from your diet, it may not only affect your vision, but may also have more effects.