64 percent of Germans wear glasses. The reason seems clear only at first glance – defective vision. But what kind of defective vision glasses must correct varies from person to person. If you’ve always wanted to know what exactly nearsightedness, farsightedness, presbyopia and astigmatism mean, you’ll find the answers here.
Nearsightedness and farsightedness
Nearsightedness (myopia) is one of the most common types of refractive error. Reliable estimates suggest that about a quarter to a third of the total population in Europe is nearsighted – to a greater or lesser degree. While some hardly notice their nearsightedness, perhaps needing glasses at most for driving, others suffer severely and cannot get through the day without correction.
All nearsighted people can see close objects perfectly sharp – but distant objects only inaccurately. This is due to the not quite exact “construction” of the nearsighted eye. Either the eye is a little too long – therefore the lens bundles the incident light rays before they reach the retina in the back of the eye. Or the eye lens has too strong a refractive power. As a result, the image hitting the retina is slightly blurred. The opposite of nearsightedness is
farsightedness (hyperopia). The farsighted eye sees well at a distance, but has problems at close range, typically when reading. There can be two reasons for this: Either the eye is a little too short. The lens does not focus the light exactly on the retina, but a little later. Or the refractive power of the lens is too weak. The image information hitting the retina is blurred. Incidentally, at a young age, the eye can still compensate for slight farsightedness by making the lens more curved. Later, the lens loses this flexibility. About 35 percent of Germans are farsighted.
Presbyopia
Presbyopia makes itself felt in everyone sooner or later. At some point, the arms are too short for daily newspaper reading, reading glasses are needed. This is due to the decreasing lens elasticity. Focusing on near objects no longer works as well as it did in younger years. Most people therefore need glasses between the ages of 40 and 50, at least in some situations. By the way, these should not be bought at the gas station or drugstore, but at a specialist store, in conjunction with an eye examination and a detailed consultation.
The reason: presbyopic eyes should be examined regularly by a specialist because the degree of presbyopia changes. In addition, declining vision in old age can also have other causes than simply presbyopia; a regular examination is therefore strongly recommended. The standard prefabricated glasses only correct the dioptres; these glasses do not provide a cylinder misalignment or a different visual correction for the left and right eye. Only one of the two eyes can see approximately well with ready-made reading glasses – if at all.
Astigmatism
Another inaccuracy of the eye can be uneven corneal curvature. Experts refer to this as astigmatism. The eye sees a point not as a point but as a rod because of the uneven distortion caused by the cornea. The brain corrects this, but the image is still somewhat unclear. All the vision problems mentioned so far can be corrected – depending on the degree of refractive error – with glasses or even with a contact lens.
