Vision problems

Myopia (near-sightedness)
If the eyeball is too long compared to the lens, it causes you to be able to see clearly at a short distance but not very clearly at a longer distance (more than 2 - 3 metres away). In myopia, the glasses should have concave lenses.
There are probably several causes of myopia, but since the number of people suffering from myopia is increasing rapidly, there is indication that it is caused especially by environmental factors. Research indicates that consumption of high glycaemic food is a probable cause. High glycaemic foods are things like sugar, bread and other foods which make the body's insulin production increase rapidly and to a high level. The high blood insulin level makes the eye grow and become too long with myopia as a consequence.
Lack of vitamin D can result in myopia.
A study has established a connection between artificial night lighting and the risk of becoming myope. In children under the age of 2, sleeping with the light on during the night resulted in 55% developing myopia. A weak night light reduced the share of myopic children to 34% and in children sleeping in the dark, only 10% became myopic.
Hypermetropia (farsightedness)
If the eyeball is too short compared to the lens, it results in you being able to see clearly at a long distance but at a shorter distance (less than 2 - 3 metres away) you will have problems seeing clearly.
Glasses for hypermetropia should have convex lenses.
Nyctalopia (night blindness)
Impaired vision when the lighting is reduced. Can be caused by vitamin A deficiency and pigmental degeneration of the retina, but can also be the result of liver disease.
An elaborate article is being prepared.