VISION DEVELOPMENT IN CHILDREN

Infants see immediately after birth and look around. They become skilled users of their vision during the first few months of life and develop eye-hand coordination. Both eyes normally look at the same object. If the child's eyes do not look at the same object the child is said to have strabismus or squint. He/she may then use his/her eyes alternatingly or only one eye all the time. If the child uses only one eye the other eye becomes a "lazy" eye, an amblyopic eye. A lazy eye cannot use central vision normally. It is important to diagnose a lazy eye early and to teach the infant to look with his lazy eye, too. Otherwise that eye will never see well.

If an infant before the age of six months seems to have crossed eyes all the time he/she should be seen by an ophthalmologist soon, not after several weeks. Even an intermittent crossing of eyes in children older than 6 months should be examined by an ophthalmologist.

When the eyes are intermittently crossed the infant sees double. Therefore he/she will accept the use of correcting glasses. If the crossing of eyes is allowed to develop manifest, i.e. present all the time, the infant no more sees double and may not accept the use of glasses.

In a family where one of the parents or older children has had strabismus or lazy eye, the younger children should be seen by an eye doctor at an early age, i.e, usually before they are 8-9 months old. It may be possible to prevent the strabismus or the lazy eye from developing if the infants get glasses early enough.

How can we observe an infant's vision at home?

It is very difficult to notice a squint (strabismus) if the eye does not turn in or out very much. Also, some infants seem to have crossed eyes even though their eyes are straight because the distance between the eyes is small and the folds at the inner corner of the eyes are still prominent, so the eyes seem to be too close to the nose.

   

Fig.25a. When an infant has big eyes and nasal folds are still prominent, the infant may seem to have inward squint, "crossed eyes", especially when the head is slightly turned.

Whenever the parents are uncertain whether the eyes of their infant are straight it is always better to let an eye doctor check the situation. After the age of 3 months the eyes are usually straight most of the time and after the age of six months all the time. Constant squint is an abnormal situation at any age.

At the age of 3 months the infant starts to play with his/her hands. Hand regard is important and teaches spacial concepts and eye-hand coordination.

If you feel that one of the baby's eyes might be a lazy eye, you can observe the child's reactions when you cover the eyes one at a time (Fig.25 and in the video Lea Symbols -Assessment of vision in pre-school years).

Fig.25. Cover test. When you cover a lazy eye with a small card or your hand without touching the skin, it may not disturb the child (A) as much as when the same card is brought in front of the other eye (B). If the child repeatedly tilts his/her head as if trying to look with eye behind the cover, the child should be seen by an eye doctor. Your hand coming from above is a better way of covering the eye.

If an infant is very hyperopic he/she sees poorly at close distances. Observation on an infant's behaviour when crawling on the floor is a good near vision test. If an infant does not recognize small bread crumbs, etc. he/she should see an eye doctor. When a hyperopic infant gets glasses his vision can develop normally.

Vision should be checked during the normal health screenings. If the child is afraid and does not cooperate with the nurse or doctor you may want to test the child's visual acuity with a playing card tests at home. If amblyopia is discovered early the results of the treatment are usually good.

Eyes and vision at school age

During puberty many children become myopic, near sighted, and need glasses in order to see well at the black board. Their eyes have not become "worse" or "weaker", they have become a little bit longer as they grew. The child's eyes are normal and he/she sees well at close distances. Glasses are needed for distance vision.

The first glasses are usually so weak that the child does not need them except in the classroom. It is better to keep them in a hard case in the school bag during pauses and on the way to school so they do not become broken.

Headache and glasses

Headache in children is seldom related to refractive errors or glasses. The most usual cause is too small a breakfast or breakfast composed of fast absorbed carbohydrates only. Then the bloodsugar will be low in the late morning and cause headache by noon or early afternoon.

Some children have swollen mucous membranes in their sinuses (Fig.10) and have therefore headaches around the eyes. This can be found out also at home as described earlier. It is good old rule that a child with headaches should play outside, eat, and spleep regularly for two weeks. If he/she still has headaches he should be seen by a doctor.

What to think and say about children's glasses ?

It is a common misunderstanding to think that eyes are "bad" if one "has to" use glasses. It is important to say to the child, now and then, that the eyes are normal so the child develops a positive self image.

Most children do not "have to use" their glasses at school age. They use their glasses as adults do, in order to see more clearly and comfortably. There are numerous situations where one does not need to have the sharpest vision. When one of the children gets glasses other children often want see how the glasses change the image. The eyes are not hurt if a child uses someone else's glasses for a while.

Children's distance vision is usually checked by the nurse at school every second year. Glasses may be in poor condition before that and have to be changed. Most opticians in Europe (in some countries optometrists) check the visual acuity if the glasses are brought in for adjustment of the frame. In childhood the usual time between the changes of glasses varies from a few months to 3-4 years.

Additional information on the development of vision is in the chapters My Sight is Important and Follow-up of vision development.

Eye accidents

Accidents are far too common among children, especially young boys. They play with sharp knives, darts or sticks that can hurt their eyes. Even scissors and a regular fork may be dangerous in the hand of a young child. Sports and games also cause accidents. In ice hockey the children should always wear a face mask and in squash protective frames. Fireworks can be very dangerous in children's hands and the home made "bombs" even more hasardous.


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