The development of a child’s eyes and vision continues after birth and lasts actively till the beginning of school age. The most suitable time for checking the eyes of a small child is at the age of 3-4 years. An ophthalmologist will test the child’s visual acuity, and mobility and optical structure of the eyes. Visual disorders should be diagnosed and treated as early as possible in order to avoid the development of amblyopia or lazy eye.
When coming to ophthalmologist’s consultation the child should be able to name or show the symbols in Dr. Lea Hyvärinen vision table for children in the ages 3-7 years.
Corrective lenses in small children
Early detection of eye diseases and vision disorders and their timely treatment are essential to ensure the development of good visual acuity of both eyes by the beginning of school age.
Therefore all children should come to the ophthalmologist to check eyes and vision at the age of 3 years.
Why are corrective lenses prescribed to a child?
When the optical structure of the eyes of the child is not in order and visual acuity is not sufficient, or if the child is suffering from squinting or strabismus, the ophthalmologist will prescribe corrective lenses for the child. Quite frequently children will get their first corrective lenses at the age of 3-4 years and they will have to wear the eyeglasses continuously till school age. However, sometimes corrective lenses are prescribed to children at the age of 1-2 years.
Eyes do not get so tired when wearing eyeglasses and the child sees more clearly both at long and short distances. Control of the ocular muscles and cooperation of both eyes is also better. Visual acuity develops faster when eyeglasses are worn correctly. Whether and to what extent eyeglasses will also have to be worn at school age depend upon how much the structure of the eyes has changed and visual acuity improved.
What has to be taken into account when choosing eyeglasses for a small child?
Suitable eyeglasses have to properly fit the child’s nose and fix firmly behind the ears. If the eyeglasses slide downwards on the nose and the handles of the eyeglasses are too long, then the child tends to look over the eyeglasses and the vision does not develop properly. Similarly, if the frame of the eyeglasses is too wide or if the handles do not fix firmly behind the ears, then the eyeglasses could come off when playing or running. The eyeglasses of a child should preferably be light and have a plastic frame.
When the child gets his/her first eyeglasses
The whole family has to adapt to the new situation when eyeglasses are prescribed to the child. It has to be placidly explained to the child at home why corrective lenses have to be worn all the time, including outside home and in nursery school. It may be difficult to wear the eyeglasses in the first weeks as the child tends to take these off frequently or say that he/she does not see clearly with the eyeglasses. This is a normal reaction. A small child does not recognise his/her vision disorder properly. The parents have to be patient and persistent when explaining the need of wearing the eyeglasses continuously. Good cooperation between the parents, child and ophthalmologist is also very important!
What is lazy eye and how is it treated?
In the event that the visual acuity of both eyes is not equal, and the vision of one eye is worse, then this amblyopic or lazy eye has to be “trained”. In addition to wearing corrective lenses, the eye that is seeing better has to be covered for certain periods of time every day, so that the child starts to also use the weaker eye more. This is called occlusion therapy and it’ duration will be determined by the ophthalmologist.
Treatment of amblyopia has to be started early as the most effective treatment period is until the age of 7-8 years. Your ophthalmologist will explain different mechanisms behind the development of amblyopia and their treatment options.
Refraction disorders in children
In order to see clearly, the rays of light have to be inclined (refracted) by the cornea and lens and then converge again in the retina. The rays of light produce an image on the retina, which contains light-sensitive nerve endings. These nerve endings form the optic nerve, which transfers the information of the image to the brain.
This inclination and convergence of the rays of light is called refraction. In case of a refraction disorder, light is not refracted properly in the eye and the rays of light converge in front not behind the retina. This causes different vision disorders.
In a hyperopic or long-sighted eye rays of light converge behind the retina; therefore, the eye has to make an effort in order to see clearly both in short and long distances.
The normal structure of the eye of a small child is slightly hyperopic, i.e. with plus-refraction. By the beginning of school age hyperopia decreases in the majority of children and they see clearly both looking at short and long distances. Slight hyperopia or long-sightedness does not cause eye problems in small children as their visual acuity is still developing. Also, children of this age are not engaged in activities that cause strain on the eyes, like studying or reading.
However, children with market hyperopia are usually prescribed corrective lenses in order for visual acuity to properly develop by school age.
The optic structure of the eye can change to minus-refraction in school age resulting in myopia or short-sightedness. In this case visual acuity is impaired when looking at far distances, but looking at short distances or reading ability is not affected if myopia is not too pronounced. Usually myopia develops at the age of 10-12 years and may progress until 18-20 years of age. After this the growth of the eye stops and myopia stabilises. If a mother or father have short-sightedness and minus eyeglasses, then myopia can also develop with high probability in their children.
Watching a TV or computer screen, or reading does not cause myopia. Still, increased strain of the eyes can cause other subjective complaints about the vision. Myopia of a schoolchild is corrected with the help of minus eyeglasses. Wearing eyeglasses does not “cure” myopia; eyeglasses are just an aid that helps the child to see well. Wearing eyeglasses does not cause progression of short-sightedness or further impairment of the child’s vision. Since myopia tends to progress with age, schoolchildren who have been prescribed eyeglasses should visit an ophthalmologist or optometrist 1-2 times a year to check their eyes. Older children can also use contact lenses besides eyeglasses. An optics shop will help to find suitable contact lenses for the child and an optometrist will also teach how to put the lenses in the eyes and take them out, and also associated hygienic precautions. If myopia is insignificant, then the child needs eyeglasses only for looking at far distances (when watching TV or a blackboard at school) as vision at short distances is also good without eyeglasses. If visual acuity is markedly decreased when looking at far distances and myopia progresses, then schoolchildren should wear eyeglasses all the time in order to see clearly both at short and far distances. Surgeries correcting visual acuity and freeing the child from the need to wear eyeglasses are not performed in children below 18 years of since the structure of their eye might change. It is also important to consider how stable the minuses of eyeglasses have been, what the structure of the cornea is, and whether the child has other eye diseases or health problems.
Astigmatism is mostly caused by the irregular structure of the cornea, i.e. when the cornea is not evenly convex and symmetrical in all its axes. Astigmatism may also be caused by changes in the shape of the lens, especially in older people suffering from the dimming of lens or age-related cataracts. When the shape of the cornea or lens is changed, rays of light passing through the eye are not projected on the retina into one point but converge as a stripe. Therefore, the person sees objects with hazy contours or with shades, and vision is not clear either at looking at short or far distances. Astigmatism frequently accompanies short or long-sightedness, and it is corrected with cylindrical glasses. Astigmatism can be hereditary.