What is hyperopia
Far-sighted people are those who cannot see close objects clearly. Usually this is due to an eyeball that is too short. Then doctors speak of one Axis hyperopia. The so-called is much rarer Refractive hyperopia: Here, the farsightedness is based on a too low refractive power of the eye, that means: The ability of the eye to bundle incoming light rays is not sufficient.
The refractive power of the eye is given in units of diopters (dpt). In the case of farsightedness, the measurement results in the refractive power Plus values (minus values for nearsightedness).
Around 20 percent of all under 30-year-olds are farsighted. For most of those affected, the refractive power of the eyes is below +4 to +5 diopters (dpt). Only a few people have higher measured values and thus an even more pronounced farsightedness.
Sharp vision near and far
In order to be able to see an object clearly, the light rays emanating from it must be refracted on the way through the eye in such a way that they meet exactly on the retina. The closer the observed object, the stronger the refraction of light in the eye has to be for a sharp image on the retina. The eye must therefore be able to change the refraction of light, i.e. be able to adapt the visual acuity to different distances. This ability of the eye is called accommodation.
Accommodation is made possible by a variable shape of the eye lens. This is responsible (in addition to the cornea) for the refraction of light in the eye. The lens of the eye is suspended by fibers on the so-called ciliary muscles:
- As the muscles contract, the lens curves more (becomes more rounded) and its refractive power increases. In this way, close objects can be shown sharply on the retina.
- When the ciliary muscles relax, the lens of the eye is elongated, i.e. flatter - the refractive power decreases so that objects further away can be seen clearly.
In order to be able to see an object that is in the middle and close to our eyes, the so-called convergence reaction takes place. The two eyeballs move towards each other, the pupils narrow, and the refractive power increases due to a stronger curvature of the lens. Accordingly, the accommodation and the convergence reaction are coupled to one another.
First of all, farsightedness means someone nearby objects not sharp can recognize. In addition, the eyes have to accommodate, i.e. they have to tense up a little, even when looking at a distance. The ciliary muscles on the lens are therefore constantly stressed. This mainly results in headaches. Further symptoms of farsightedness are:
- rapid fatigue of the eyes
- Eye pain
- Burning eyes
These symptoms are also covered by the term asthenopic complaints summarized. They are especially noticeable when reading.
Since, from an anatomical point of view, the increase in refractive power and the movement of the eyes towards each other (convergence reaction) are coupled to one another, inward strabismus is another possible symptom of farsightedness.
Farsightedness: causes and risk factors
The reason for the farsightedness can either lie in an eyeball that is too short (axial farsightedness) or a reduced refractive power of the lens (refractive farsightedness).
Axis farsightedness (axis hyperopia)
Axial farsightedness is by far the most common: because the eyeball is shorter than normal here, the image is not sharply focused on the retina even with maximum accommodation - the incident light rays would only meet behind the retina in a common focal point. Therefore, people with farsightedness cannot see close objects clearly.
In the distance, an affected person can see clearly, but the eye lens must also be accommodated because its refractive power in the relaxed state is not sufficient even for distant objects. This is why the ciliary muscles, which cause the lens to curve and thus increase the refractive power, are constantly tense.
With distant vision and farsightedness of up to 4 dpt, this is not a problem for a young person. However, in order to be able to see something sharp at a reading distance (about 33 centimeters), a further 3 dpt refractive power are necessary. That means a total refractive power of 7 D that has to be provided. In the long run, this cannot be achieved by the eye and causes discomfort.
Refractive farsightedness (refractive hyperopia)
In refractive hyperopia, the eyeball is of normal length, but the refractive power of the lens is lower than normal. The consequences are the same as with axial farsightedness.
Far-sightedness in old age
You can find out how far-sightedness develops in old age in the article Presbyopia.
Farsightedness: examinations and diagnosis
If you experience problems with your vision, you should see an ophthalmologist. He will first ask you in detail about your Medical history (Anamnese). He will ask you the following questions, among others:
- How long have you had complaints?
- Are you having trouble reading?
- Do you have a headache?
- Do you wear glasses?
Then the doctor will examine your eyes. To clarify a possible farsightedness, the Measure the refractive power of the eyes - using infrared light or a laser beam. Before that, you will be given eye drops to dilate the pupils.
The effect of the eye drops - that is, the dilatation of the pupils - lasts for a long time, which is why you are not allowed to drive a car for several hours afterwards. Keep this in mind when planning your visit to the ophthalmologist!
Eye tests allow a statement to be made about the visual acuity of the eyes. To do this, you need to recognize different letters, numbers or shapes that are presented to you at a certain distance. The different characters get smaller from line to line. According to the line that you can still clearly see, your visual performance will then be assessed in relation to the distance.
Another exam at the ophthalmologist is that Reflection of the fundus (Funduscopy). The ophthalmologist shines a light into your eye to assess the retina. Sometimes changes can be seen in the fundus of the eye, especially in the case of severe farsightedness. For example, tortuous vessels can be seen on the retina (tortuositas vasorum).
Read more about the examinations
Find out here which examinations can be useful for this disease:
The farsightedness can be with a Visual aid - glasses or contact lenses - to be balanced. So-called Plus glasses used (also called collecting lenses). They are curved outwards (convex). As a result, they bundle the incident light rays before they hit the cornea. This supporting refraction of light means that the relatively weak refractive power of the eye is sufficient to produce a sharp image on the retina.
In the case of very severe hyperopia, contact lenses are usually preferred because the glasses required for correction would be very thick and heavy.
As a further treatment option, you can have your eyes lasered if you have farsightedness. Often the procedure is called Laser in-situ keratomileusis (LASIK). The upper half of the cornea is planed off with a computer-controlled blade. The ophthalmologist then brushes the resulting lamella aside before using the excimer laser to grind the inside of the cornea so that its curvature increases and the refractive power increases. In some cases, a second surgery is required to achieve the desired result. With LASIK, up to six diopters can be compensated.
In rare cases, laser treatment for farsightedness can leave a scar on the cornea. Seeing is then no longer possible and a corneal transplant is necessary.
Farsightedness: treatment for aphakia
Sometimes the reason for the farsightedness is a lenslessness (aphakia), for example after the surgical removal of the eye lens in cataracts. Then a converging lens of +12 D can be used as a visual aid or a new lens can be surgically inserted into the eye.
Read more about the therapies
Read more about therapies that can help here:
Farsightedness: disease course and prognosis
Unlike nearsightedness, which often increases over time, farsightedness rarely changes in strength over the course of life.
A strong and constant accommodation, however, favors one Squinting inward. As a result, a child can develop Weak-sightedness Develop (amblyopia): One eye is then only marginally involved in the visual process. This is because squinting creates double vision. These confuse the brain so that it permanently suppresses the information from one eye.
The "sluggish" eye can still be trained in childhood if the active eye is repeatedly immobilized - this is traditionally done with a plaster over the eye, sometimes drops are enough. In addition, there are glasses that correct the ametropia. In some cases, surgery is needed to correct the squint. The earlier the treatment, the better the chances of recovery. After puberty, amblyopia can no longer be corrected because the brain is no longer flexible enough.
Many people with farsightedness have an eyeball that is too short. As a result, the space between the cornea and the iris (called the anterior chamber) is unusually small. In addition, the ciliary muscle is often thickened due to the heavy use. This makes the so-called chamber angle, which is at the edge of the iris and cornea, very narrow. If it becomes too tight or even closed, angle-closure glaucoma (form of glaucoma) can develop. The pressure in the eye can rise dangerously high. So the risk of angle closure glaucoma is at Farsightedness clearly increased.
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