Every second Austrian has ametropia – and the trend is rising
Around 3.7 million Austrians over the age of 16 have vision defects or are ametropic. Of these, 1.7 million are permanent and 2.0 million are occasional wearing glasses. 87% of Austrians wearing glasses also need glasses when reading, 8% wear contact lenses at least occasionally.
What does ametropia mean?
Clear vision requires that the focal point of the incident light is exactly on the retina. In the optimal case the light in the eye is refracted accordingly; otherwise there is ametropia:
• In the short-sighted eye (myopia), the focal point is in front of the retina. Objects that are further away are perceived as blurry.
• In the farsighted eye (hyperopia) it is the other way around: the focal point is behind the retina. Nearby objects appear blurry.
• In the case of astigmatism or astigmatic eyes, the focal point on the retina is distorted – all objects appear distorted accordingly.
• With increasing age, so-called presbyopia occurs. The eye loses the ability to focus on different distances – additional corrective lenses for reading are needed.
The eyelength of myopic people is too long in relation to the refractive power of the cornea and lens. This means that rays of light that enter the eye from distanced are bundled in front of the retina and therefore the image appears blurred. In contrast, the eye sees better at near.
Severe myopia can be associated with stretching of the retina and is considered a risk factor for retinal tears or retinal detachment. This profound myopia can be hereditary.
Short-sightedness can be compensated for with diverging lenses (minus lenses) in glasses or appropriate contact lenses. These lenses are thinner in the middle than at the periphery. They diverge the bundle of light rays and thus ensure that they only come together to form the focal point on the retina.
Anyone who finds visual aids annoying can also have their short-sightedness surgically corrected.
You can find out more about refractive surgery procedures here.
There is a global trend towards increasing myopia. According to calculations, 50% of all children will be short-sighted by 2030. In many Asian countries such as China already today more than 80% of all children are myopic. You can find out more about the treatment of myopia in children here
In contrast to myopia, hyperopes have an eye that is too short. As a result, the rays of light only come together behind the retina.
Hyperopia can be compensated for with converging lenses that are thicker in the middle than at the edge. Surgical correction using refractive surgery is also possible within certain limits. You can find out more about refractive surgery here.
Normally, the cornea has a spherical shape and an even refractive power. An astigmatic cornea is curved in such a way that the refractive power in the individual planes (meridians) of the cornea is different. Incident light rays are therefore not focused as a point on the retina, but are drawn into a line (hence the term “astigmatism”). This form of ametropia is often associated with myopia or hyperopia.
Astigmatism can be compensated for with cylindrical glasses or special contact lenses. Various surgical procedures, such as laser surgery or the implantation of toric lenses, also allow the correction of astigmatism.
The ability of the eye to focus visual acuity on objects at different distances is called “accommodation”. This enables the human eye to see things that are far away as well as things that are close by.
However, this ability is lost from the age of around 45. From this age on, normal-sighted people can only see objects in the distance sharply; for close-up, for example to read a newspaper, they need reading glasses. Myopic people, who naturally see better at near can usually manage without reading glasses a little longer.
Despite intensive research in this field, it is still not possible to cure presbyopia or to completely restore accommodation (near focus reflex).
Treatment of presbyopia usually consists of using reading glasses, varifocal glasses (progressive glasses) or multifocal contact lenses to enable clear near vision again.
The strength of the glasses depends on the age and the desired reading or working distance. The following applies: the closer the reading text has to be the stronger the glasses must be. If you already have ametropia (i.e. astigmatism, far-sightedness or near-sightedness) in addition to your presbyopia, combined glasses (so-called varifocal glasses) are most likely to be suitable for you.
Instead of glasses, contact lenses can also be used to correct presbyopia: If you have previously corrected your ametropia with contact lenses and also want to compensate for presbyopia with this visual aid, you can opt for multifocal lenses (also called multifocal lenses).