Refractive errors


Having a visual error is common. It can either make you look bad in the near or far, or both. Some visual defects can cause you headaches and tired eyes. Visual errors are corrected with glasses or contact lenses.

Visual errors are often due to light refraction in the eye, which is sometimes called refractive error. Common vision errors:

  • Nearsightedness.
  • Myopia – myopia.
  • Astigmatism.
  • Presbyopia.

In this text, you can read about these vision errors and how they are corrected. Here you can read more about the scolding in children and the scolding and double vision in adults.

Symptoms of refractive errors

In the event of a visual error, you will see clearly in either short or long distance. Some look unclear both in the short and long run.

You may also have other symptoms of refractive errors such as feeling tired in the eyes, pee, blinking a lot and getting a headache.

Different types of vision errors

There are different types of vision errors. The symptoms vary depending on your vision error.


Myopia means that you see clearly up close but not clear in the long distance.

Myopia has an inherited part and is developing slowly. It often starts in the teens and usually stabilizes before the age of 30.

Vision often gets worse on both eyes, but not always as much. You usually see more clearly if you pee.

Myopia does not usually cause you to become tired or get hurt in your head, unlike other vision errors.

Myopia – myopia

Oversight often means you look better in the long run than up close. When you need to lookup close, it becomes more difficult for the eyes. You may feel tired in the eyes and get headaches.

During myopia, it is common to have poor vision in the long run in the middle age.

The heredity of myopia is not as great as myopia.


Astigmatism is a visual error that is usually due to the cornea being uneven.

If astigmatism is large enough, the vision is disturbed both near and far.

Astigmatism, for example, allows you to be both nearsighted and farsighted in the same eye. This is strenuous to the eye and can cause you tired eyes and headaches.


Age-related vision is due to the ability of the lens to adjust the correct visual acuity at different distances as you get older, usually in middle age.

It is common for you at first to find it difficult to read the fine text in low light or at normal reading distance. The text gets blurred and blends together. The eyes may feel strained and you may get a headache. The transition from near-sighted to distance-sighted often becomes slower if you have the age-related vision. It can be disruptive for those who often need to switch focus from near to far.

When and where should I seek care?

Contact an optician if you think you have a visual impairment.


To examine your visual acuity, a visual examination is performed by an optician or an ophthalmologist. During the survey, you will read a letter board. On the top row, the letters are large, then they become smaller and smaller on the rows below.

To find out which eyeglass strength is best for you, the optician or ophthalmologist tests glasses with different strengths during vision measurement. You tell which glass you think you look best with.

Sometimes a so-called autorefractor is used. It is an appliance that measures your vision error and offers glass suggestions that may be suitable for your vision error. The optician or ophthalmologist then assumes the measured values ​​when glasses of different strengths are tested on you.

During the examination, you and the optician arrive at a glass strength or a combination of glass strengths that gives you full visual acuity. If visual acuity is still impaired despite the best possible glass strength, you have a visual impairment that is not due to refractive error.

Treatment of refractive errors

The common vision errors can be corrected with the help of glasses or contact lenses. Glasses used to have lenses made of glass but today these are usually made of plastic.


Glasses can be single-cut, double-cut or progressive. Single-cut glasses have the same strength over the entire glass surface. Double-cut glass has a strength in the upper part of the glass and another strength in the lower part. Progressive glass is a refinement of double-glazed glass. The boundary between the glasses’ strength from the upper part of the glass to the lower part is stepless. There is no sharp line between the various forces.

Double-cut or progressive lenses are used when the eye has difficulty adjusting for different distances, which is most common in age vision. There are also progressive contact lenses. It may take a while to get used to progressive lenses or contact lenses. Some may not get used to progressive lenses or contact lenses.


Contact lenses are applied directly to the surface of the eye, usually on the cornea. The lenses can be soft or hard. Soft lenses are the most common.

Should I choose glasses or lenses?

For most vision errors, the choice between glasses and lenses is a matter of what you like most. You can usually get equally good eyesight with both.

There are exceptions. In the case of severe vision errors, contact lenses may be the best or sometimes the only treatment method.

The strength of the glasses and lenses

To correct your vision error, the glasses or lenses have some strength. The strength is on the recipe that you get after an eye examination. It is common to have different strengths on the right and on the left eye.

Monovision can help with aging

A less common solution for aging is monovision. This means that you wear glasses or contact lenses that make one eye look sharply close up and the other sharply close. The brain then learns to continuously use the eye needed for each distance. In some, the brain does not learn this.

Operation and laser treatment of refractive error

Some refractive errors can be corrected with surgery or laser treatment of refractive errors. There are several methods, and the method that suits you depends on which refractive error you have. Read more about surgery in case of refractive error here. 

What happens in the body?

When you look at something, the cornea of ​​the eye and lens focus on the light so that a sharp image on the retina is created.

If you have a visual defect, the image on the retina will not be sharp. The focus of the image is then either in front of or behind the retina. How the light shines depends on the type of refractive error you have.


In myopia, the light is refracted so that the focus of the image falls in front of the retina. It can be described simply as the eye is too long.


During oversight, the light is refracted in a way that causes the focus of the image to fall behind the retina. It can be described simply as the eye is too short.


Astigmatism is usually due to the cornea of ​​the eye having different curvature at different angles, much like an egg. The consequence of this is that the eye can be nearsighted in one angle and overshadowed at another angle and then there is never a sharp image in the entire image on the retina.


In the case of age vision, the lens’s ability to set sharp images for different distances is impaired, among other things.

The ability to change your vision from far and near is called accommodation. It is common for this to become more difficult after the age of forty and for many there is no accommodation available at retirement age.

Visually impaired in children

Children can have refractive errors just like adults. Vision errors that require glasses are most often detected at the visit to bvc when the child is four or five years old. Oversight is common in children and grows away for most people. Children are born with impaired vision and must train the vision to be able to achieve full visual acuity at five to six years of age. In order to train the vision to normal vision, the image on the retina must be sharp.

Survey on children

In a visual examination on preschool children, pictograms with symbols or letters are often used. For even younger children, special boards are used.

Children have strong accommodation. This makes it difficult to obtain reliable values ​​of the visual error with the method of different glasses’ strength, which is common in adults.

Therefore, in order to improve the measurement, the child first receives pupillary eye drops which inhibit the accommodation. Thereafter, the visual error can be measured in several ways:

  • With different eyeglass strength and synthesis board, if the child can handle it.
  • With an autorefractor. It is an appliance that automatically measures your refractive error and provides suggestions on eyewear strengths that may be suitable.
  • With a ski copy with the flashlight. Skiscopy is a manual method for determining refractive error. The method means that the eye doctor looks at how a light reflex moves in the pupil while the eye doctor holds different eyeglasses lenses in front of the eye. In this way, the ophthalmologist can calculate the magnitude of the refractive error.

Glasses Contributions

From 1 March 2016, children and young adults will receive a contribution to glasses for the visual impairment they have, a so-called glasses grant. The grant is valid from 0 years up to the age of 19. For children up to the age of eight, each county council and region decide the size of the grant itself. Thereafter it is at least SEK 800 and also applies to contact lenses. If the glasses or lenses cost less than SEK 800, the refund is equal to the cost. Opticians handle the grant.

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