Hyperopia – What is it?
Hyperopia (farsightedness) is a vision defect that causes those affected to perceive objects at close range out of focus. Objects in the distance, on the other hand, appear sharp. In this article, you can find out more about the types of hyperopia, the symptoms of farsightedness and the treatment options using visual aids or laser eye surgery.
Farsightedness – development and causes
The focal point of the incident light rays should normally lie on the retina. In farsighted people, however, the focal point lies behind the retina, resulting in a blurred image at close range. The defective vision is indicated by a plus value (e.g. + 3 diopters). Farsightedness is often hereditary and congenital.
Different types of hyperopia
One cause of long-sightedness is an eyeball that is too short – in this case it is called axial hyperopia. This is the most common form of long-sightedness. A shortening of the axis by one millimeter already leads to farsightedness of +3 diopters.
Another type of long-sightedness is refractive hyperopia. In this case, the dioptric apparatus – in particular the cornea or the lens of the eye – has insufficient refractive power, while the eyeball is normal. Refractive hyperopia occurs far less frequently. Causes of refractive hyperopia can be
- Corneal changes
- Corneal diseases
- Lens misalignment or absence of the lens
Symptoms of long-sightedness
Unnoticed and untreated hyperopia can manifest itself through various symptoms. Those affected continuously strain the eye muscles (ciliary muscle) and can thus adjust the curvature of the lens – this automatic process can compensate for farsightedness to a certain extent (so-called accommodation). In the long term, excessive strain can lead to eye strain. This results in complaints such as
- Eye pain
- Conjunctivitis
- Headache
- Increased lacrimation
Accommodation is one reason why defective vision is rarely noticed at a young age . This is referred to as latent (= hidden) hyperopia. From the age of 30, the lens of the eye becomes less and less flexible due to the body’s natural ageing process. Due to the lack of flexibility, the ability to accommodate decreases. As a result, those affected perceive blurred vision more and more clearly.
Hyperopia diagnosis: How farsightedness is diagnosed
After taking a detailed medical history, the ophthalmologist will carry out various examinations. These include in particular the eye test, the subjective refraction test. During the eye test, patients have to recognize letters and numbers of different sizes. The answers are used to assess visual performance and determine a correction value.
In addition to the subjective refraction determination, an objective refraction determination is carried out using a refractometer. This is an automated test to determine the correction value, also known as a computer vision test. A funduscopy (mirroring of the back of the eye) is often also carried out to examine the retina.
In young people and children, the results of the refraction determination can be distorted by natural accommodation. For this reason, eye drops are applied before the examination, which temporarily cancel out the curvature of the lens of the eye.
Treatment options for hyperopia
If hyperopia leads to symptoms, there are two options available to those affected to correct the defective vision: wearing visual aids or undergoing surgery.
Visual aids such as glasses and contact lenses
In contrast to short-sightedness (myopia), converging lenses are used instead of diverging lenses for long-sightedness. The converging lenses focus the light and project it directly onto the retina. The result is a sharp image.
Contact lenses can also be considered, which have the same effect as spectacles with converging lenses. They offer the advantage that the field of vision is not restricted. However, careful handling is necessary to avoid corneal damage or infections.
Refractive surgery: laser eye surgery for long-sightedness
Surgical procedures are becoming increasingly popular due to their high success rate and low complication rate. Several procedures are possible, including
- LASIK / Fetmo-LASIK
- PRK / Trans-PRK
- ReLEx SMILE or SmartSight
- Implantable contact lenses – ICL Phake lenses
- Refractive lens exchange or cataract surgery
LASIK, ReLEx SMILE and PRK are procedures that are performed using a laser. During laser eye surgery, the tissue of the cornea is removed and the refractive power is adjusted as a result. The prerequisite for laser eye surgery is a sufficiently thick and stable cornea – this is determined by the treating doctor during a preliminary examination.
In addition, intraocular contact lenses can be inserted behind the iris. Lens procedures are generally used for particularly pronounced defective vision.
Consequences of hyperopia
Farsightedness can favor some diseases. If axial hyperopia is present, there is an increased risk of developing glaucoma. This is caused by the angle of the eye being too narrow, which impairs the outflow of aqueous humor. This can result in increased intraocular pressure, which causes damage to the optic nerve .
Difference to presbyopia
While hyperopia is a refractive error, presbyopia is due to an age-related process. Eyes with normal vision also accommodate in order to produce a sharp image. With advancing age, the lens of the eye becomes increasingly rigid, causing the ability to accommodate to steadily decrease. This consequence of this process is known as presbyopia.
Presbyopia often only becomes noticeable when the ability to accommodate is so limited that there is a value of three diopters. From the age of 45, many people need reading glasses. From the age of 60, accommodation is almost completely restricted. The first signs of presbyopia are
- Feeling of effort when reading
- Headache
- Feeling of pressure in the forehead
- Eye pain
Farsightedness in children
Children can also suffer from long-sightedness. Children are often born with mild hyperopia. From the age of 6, normal vision usually returns due to growth. In exceptional cases, however, farsightedness is so pronounced that children also need a visual aid and an ophthalmologist should always be consulted if hyperopia is suspected. Uncorrected and pronounced farsightedness in children can cause inward squinting or amblyopia.