Far-sightedness (hyperopia)
Do you find it increasingly difficult to read a book because you are no longer able to recognise the letters correctly and it means you have to keep the book farther away from you in order to be able to continue reading it?
And by contrast, have you probably noticed that it’s still no problem to see people and objects sharply and clearly from a distance?
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.
Symptoms
Constant accommodation, i.e. constant adaptation through tensing and relaxing the eyes, leads to headaches in particular. When the ciliary muscles relax, the lens of the eye is extended, making it flatter. As a result, their refractive power decreases, allowing more distant objects to be seen in sharp focus.
Other symptoms of far0sightedness include:
- Rapid fatigue of the eyes
- Eye pain
- Burning eyes
- Conjunctivitis
In medical terminology, these symptoms are also referred to as asthenopia. They are generally more noticeable when reading.
Since the increase in refractive power and the movement of the eyes (known as the convergence reflex) are anatomically linked to one other, inward strabismus is another possible symptom of far-sightedness.
The convergence reflex always takes place when an object is to be viewed that is located centrally and close to our eyes. Both eyeballs move towards each other, the pupils constrict and the refractive power increases due to the stronger curvature of the lens. Accordingly, accommodation and the convergence reflex are linked.
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.
Diagnosis
If you have problems with vision, you should make an appointment with an ophthalmologist as soon as possible. He or she will first ask you in detail about your medical history, or case history. Among other things, your ophthalmologist will want to find out how long you have had the symptoms and whether they are mainly noticeable when you read. He or she will also want to know if you suffer from a headache and if you are already wearing glasses – maybe even if just for reading.
The doctor can draw a conclusion about the visual acuity of your eyes by means of an eye test. In the course of this test, you have to identify different letters, numbers or shapes that are projected onto the wall at a certain distance from you. The various symbols or numbers become smaller as you move down the rows. The ophthalmologist will assess your vision according to the last line that you were able to identify/read without any problems.
A further examination in connection with determining far-sightedness is the reflection of the back of the eye (known by the medical term funduscopy). The ophthalmologist shines a light into your eye to assess the retina. This sometimes allows changes to the back of the eye to be detected, especially in cases of severe age-related far-sightedness. For example, narrowed vessels on the retina may be visible.
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.
Aftercare
If you have been diagnosed with far-sightedness, it is important and essential that you consult your ophthalmologist at regular intervals and have your eyes examined.
FAQ
What happens in the eye if someone is far-sighted?
If someone is far-sighted (known by the medical terms hyperopia or hypermetropia), either the refraction of light in the eye (= the eye’s ability to focus incoming light rays) is insufficient or the eyeball is too short (known as axial hyperopia) to see near objects in sharp focus. Correspondingly, those affected have problems reading. This often leads to headaches and eye ache. Near-distance vision can be improved with the help of glasses or contact lenses – surgery is rarely performed. The eye’s refractive power is measured in the unit dioptre (dpt for short); in the case of far-sightedness, the refractive power is measured as positive values, whereas in the case of near-sightedness, it is measured as negative values.
Once far-sighted, always far-sighted?
Early detection of far-sightedness can prevent the development of such a visual disturbance if corrective glasses are prescribed in good time. As the eyeball grows, the long-sightedness can correct itself again (especially in small children).
Is a severe deterioration of far-sightedness possible?
If the far-sightedness is recognised and treated promptly, it rarely worsens over time. On the contrary: in children and adolescents, it often goes into reverse due to the fact that more time is spent looking at a screen and less time outdoors, and can even turn into near-sightedness.
