Far-sightedness (hyperopia)

What is far-sightedness?

In order to be able to see an object clearly, the rays of light reflected off it must be refracted on its way through the eye in such a way that they converge exactly on the retina. The closer the object is in front of the eye, the stronger the refraction of light must be in the eye to create a sharp image on the retina. The eye must therefore be able to alter the refraction of light and adjust the visual acuity to different distances (known as accommodation).

First and foremost, far-sightedness means that you can no longer clearly identify objects close by. The ciliary muscles (i.e. the fibres on which the lens of the eye is suspended) of the lens are therefore under permanently strain, because as soon as these muscles contract, your lens curves more strongly (i.e. becomes rounder) and the refractive power increases, allowing close objects to be projected sharply on the retina. Your eye muscles also need to be tensed somewhat on a regular basis to look into the distance.

Causes

The reasons for the far-sightedness may be either a short eyeball or reduced refractive power of the lens. Age-related far-sightedness is also possible.

Axial far-sightedness (axial hyperopia)

Axial far-sightedness is the most common form of far-sightedness: Since the eyeball is shorter than normal, the image is not projected sharply on the retina even with maximum accommodation – the light rays entering the eye would not converge in a focal point until beyond the retina. For this reason, far-sighted people are unable to see near-distance objects clearly.

The affected person can still see clearly in the distance, but the eye lens must also be accommodated because its refractive power in a relaxed state is insufficient even for distant objects. Therefore, the ciliary muscles, which create a curvature of the lens and therefore an increase in refractive power, are constantly tensed.

This is not a problem for a young person with looking into the distance with a far-sightedness of up to 4 dioptres. However, in order to be able to focus a little at the reading distance, i.e. about 33 centimetres away from the body, a further 3 dioptres of refractive power are necessary. This means that the eye needs to have a total refractive power of 7 dioptres, which the eye is unable to provide in the long term, and is the reason why symptoms ultimately occur.

Refractive far-sightedness (refractive hyperopia)

In refractive hyperopia, the eyeball is normally long, but the refractive power of the lens is lower than normal. The consequences of refractive far-sightedness are no different from those of axial far-sightedness.

Age-related far-sightedness (presbyopia)

Presbyopia (or age-related far-sightedness) is caused by the ageing of the eye lens. It usually becomes noticeable from the age of 45. As with the actual far-sightedness, those affected have problems reading at the normal reading distance. However, this problem can be resolved with suitable reading glasses.

Treatments

Far-sightedness can be compensated for with a pair of vision aids, i.e. glasses or contact lenses.

These contain converging lenses, also known as plus lenses, which curve outwards (= convex). This outward curve ensures that the light rays entering the eye are already focused before they fall onto the cornea. Thanks to this supportive refraction of light, the weak refractive power of the eye is sufficient to project a sharp image on the retina. In the case of very severe hyperopia, contact lenses are usually preferred because the lenses required for correction would be very thick and heavy.

Another treatment option is laser eye treatment to improve the vision of your eyes.