Hyperopia

Normally, the eye refracts incoming light to bring it into focus on the retina. Hyperopia is a type of refractive error in which the light comes into focus behind the retina. To see what is at hand, the eye must accommodate. This puts strain on the eye and causes a variety of symptoms in the eye and body.

This article describes following topics.

・Causes and Symptoms of Hyperopia
・Differences from presbyopia
・Things to be aware of and measures to take for hyperopia in children

Light entering the eye is refracted through the cornea and lens to reach the retina at the back of the eye. The eye accommodates (focuses) by changing the thickness of the lens so that it is in focus on the retina. An eye that is in focus on the retina without accommodation when looking into the distance is called emmetropia.

Hyperopia is a refractive error in which when you look in the distance, if you don’t accommodate, the eyes will focus behind the retina. When the accommodative function is working, the eye can see relatively well at a distance, but cannot see clearly at close distance because the retina is not in focus.

Hyperopia is often misunderstood as “good distance vision.” In fact, because the focus is behind the retina, the eye must be constantly adjusted whether you are looking at both distance and near. This can tire your eyes and your body easily.

There are two types of hyperopia, known as axial and refractive hyperopia.
Most people with hyperopia have a mixture of both axial and refractive hyperopia.

Axial hyperopia

The length of the eyeball in the depth direction in the diagram is called the axial length. Axial hyperopia is a condition in which the eye cannot focus on the retina because the axial length is too short.
Newborn babies often have hyperopia. This is due to the small size of the eyeball and the short axial length. In most cases, the condition will normalize as the child grows, but there are cases where the hyperopia remains.

Refractive Hyperopia

Refractive hyperopia is caused by weak refractive power of the lens or cornea. Refractive hyperopia may occur after refractive surgery, such as LASIK surgery, or due to cortical cataracts.

IT ophthalmopathy is more likely to occur when a person with hyperopia spends long time working on a computer or other tasks.

Symptoms of IT ophthalmopathy include:

・Eye fatigue
・Pain behind the eyes
・Tension in the shoulders
・Tension in the neck
・Autonomic nervous system symptoms such as headache, nausea, and dizziness

These various symptoms can make it difficult to maintain concentration or perform detailed tasks for long periods of time.

The presence and degree of hyperopia can be determined by checking refractive power using an instrument　called an “autorefractometer.”
When testing children, eye drops that temporarily block eye accommodation may be used, as the child’s eyes have a strong ability to accommodate.

While hyperopia is caused by refractive error, presbyopia is caused by the deterioration of the accommodation function of the eyes as it ages. As presbyopia progresses, the lens becomes hardened, making it difficult to focus, especially when looking at close objects.
There is a common misconception that people with hyperopia are more likely to develop presbyopia or that presbyopia progresses more quickly, but it is more accurate that people with hyperopia notice presbyopia earlier.
Since hyperopic people need to constantly use their eyes’ ability to accommodate both far-away and near objects, they experience significant “difficulty in seeing” when their ability to accommodate starts to decline with age. On the other hand, myopic people, who have an easier time seeing things up close, tend not to notice a decline in their ability to accommodate.
It is important to note that presbyopia occurs to everyone, regardless of whether they are farsighted or nearsighted.

For more information on presbyopia and related measures, please click here.

Most babies are born with mild hyperopia, and as they grow up, their eyes grow and their visual acuity
develops until they reach about age 13. However, if the degree of hyperopia is severe, children often remain farsighted.
Children who are born with poor vision do not complain about it. Unlike myopia, this condition may not be evident on a vision test, but children whose eyes tire easily may also have trouble concentrating. It is important to be aware that hyperopia in children can lead to amblyopia and strabismus.

Amblyopia

Amblyopia is a condition where the development of vision is hindered and vision in one eye is reduced. Even with correction using glasses, vision does not improve to the desired level. Amblyopia occurs when a child grows up without being able to focus on the retina until around age 8, when vision develops.
A child with high hyperopia will always have blurred images even when the eye tries to focus, resulting in a lack of stimulation necessary for the development of visual acuity.
As the age of the child grows, vision development becomes more difficult, so early detection and early initiation of treatment is important.

*For more information on amblyopia, please click here.

Strabismus

Strabismus is when the eyes do not look in the same direction, for example when one eye looks straight ahead while the other looks in another direction. People with hyperopia tend to have both eyes turn inwards to accommodate, which can result in accommodative esotropia, where the pupils turn inwards.
Strabismus can cause impaired depth perception and double vision. If you have accommodative esotropia, you can correct it by wearing glasses to correct your hyperopia.
As with amblyopia, it is important to begin treatment as early as possible.

*For more information on strabismus, please click here.

Generally, mild hyperopia does not affect vision and does not require correction with glasses, but if it interferes with daily life or is accompanied by strabismus or amblyopia, correction with glasses is necessary.

People who do desk work using a computer or whose jobs require them to look at close range can reduce the strain on their eyes and relieve the symptoms of eye strain by using glasses or contact lenses.

Left untreated to a certain extent, hyperopia can not only worsen shoulder tension and headaches, but also make it difficult to concentrate on reading or other tasks, which can reduce your study or work efficiency.

If you are concerned about your symptoms, have a refraction examination with an ophthalmologist and then have spectacles made at an optician based on your doctor’s prescription. In hyperopia, as shown in the figure, a convex lens is used to move the focal point that forms behind the retina to focus on the retina.

How does hyperopia affect my vision?

Hyperopia is a condition in which the eye focuses behind the retina, making it difficult to see both near and far. If the degree of hyperopia is mild, it is unlikely to affect the vision, although there is a strain on the accommodation function of the eyes. However, because the eye must continually accommodate, the eye may tire more easily than in emmetropia and it may be difficult to concentrate on work.

What is hyperopia in simple terms?

Normally, when light entering the eye forms an image on the retina, it is called emmetropia. In contrast, hyperopia is a condition in which the images are focused behind the retina. This is caused by the eye not having enough length or a weak ability to refract light.

How can I check for hyperopia by myself?

A characteristic of hyperopia is that it rarely shows up numerically in vision test results. Even if you can see well with the naked eye, symptoms such as eye fatigue, pain behind the eyes, tension in the shoulders, or headaches may be caused by hyperopia. If you are concerned, you should see an ophthalmologist.