How do you show greater foresight? Why

Self-magnification with the spectacle lens

What does self-enlargement mean?

The term self-magnification describes the magnification caused by the lens Resizing the image that falls on the retina. It is created by the curvature in the middle of the glass. Far-sightedness is corrected with converging lenses, these are thickest in the middle. In the case of nearsightedness, however, diverging lenses are used, which are thinnest in the middle. Therefore, the eyes appear enlarged or reduced through the glasses, depending on the ametropia. The further the glasses are from the eyes, the stronger the effect. Incidentally, contact lenses have no self-magnification because they sit directly on the cornea.

Avoid magnifying glasses yourself

The self-magnification is particularly noticeable in farsighted people with more than +2.0 diopters. Many people who wear glasses find them aesthetically disturbing because they make their eyes look unnaturally large. The image quality also suffers from the curved lenses: the closer you look to the edge of the glasses, the blurrier and more distorted you see.

To remedy the situation thinner lenses, which reduce the self-magnification and improve the image quality. This requires material with a higher refractive index. Because the more the light is refracted in the lens, the thinner it can be ground. Plastic glasses can have a maximum index of 1.74 - this corresponds extra thin premium glasses. Mineral glasses have a refractive index of up to 1.9. But they are heavier for that.

Self-magnification with different correction values

If the visual acuity of your two eyes is very different from one another, the magnification behind the lenses will make them appear different sizes. Another effect can also occur: a larger image is projected onto the retina of one eye than that of the other. This leads to blurred or blurred vision. A higher refractive index glass material can help here. However, if the difference between the two eyes is too great or if the visual acuity is extremely strong, contact lenses are more suitable, as there is no magnifying effect here.