Children’s eye health and choosing glasses

Medical Optics

CHILDREN’S EYE HEALTH AND

CHOOSING GLASSES FOR YOUR CHILD

COMMONEST EYE CONDITIONS IN CHILDREN

The 3 commonest eye conditions in children are the following

1. Refractive errors (myopia, astigmatism and hyperopia)

2. Amblyopia or “Lazy Eye”3. Squint or “Turn” of the eye

We will now discuss these three conditions in more detail

A refractive error causes blurring in a child’s vision and if significant it should be corrected by wearing glasses.

In most cases it is important for your child to start wearing the glasses at the earliest opportunity as the visual part of the brain only develops properly if it is presented with a well focused clear image from the eyes.

Failure to do this will result in amblyopia or “lazy eye” which can be rectified to some degree by “patching”

REFRACTIVE ERRORSMYOPIA, ASTIGMATISM AND

HYPEROPIA

Myopia means “short sighted” and your child cannot see properly in the distance but is able to read clearly

It sometimes takes a while for parents to become aware of this condition as it develops slowly as the eyes grow. Often the teacher will say that your child needs to sit near the front of the class to see the blackboard or you might notice that your child sits near the T.V. to see it clearly

Myopia is the easiest refractive error to treat and rarely causes amblyopia or “lazy eye”. A pair of glasses is all that is usually required. The glasses should be worn 90% of the time

REFRACTIVE ERRORSMYOPIA, ASTIGMATISM AND

HYPEROPIA

MYOPIA

You can see that this little girl has myopia by looking at her glasses. Her eyes appear smaller behind the lenses. This is particularly obvious when looking at her right eye – you can see the edge of her cheek within the lens

Astigmatism is when the front of the eye or “cornea” is shaped like the surface of a rugby ball, instead of the normal soccer ball or “spherical” shape

This means that there are two focal planes presented to the retina (fi lm at the back of the eye) and your child sees a blurred image rather than a clear image

Astigmatism is a leading cause of “lazy eye” and if there is a history of this condition in the family then all your children should be examined by an eye doctor at an early age

REFRACTIVE ERRORSMYOPIA, ASTIGMATISM AND

HYPEROPIA

There are three types of astigmatism i.e. myopic astigmatism, hyperopic astigmatism or mixed astigmatism

It is not possible to tell if a child has astigmatism by looking at their glasses

ASTIGMATISM

Hyperopia means “long-sighted” and this condition can also cause amblyopia or “lazy eye”. In addition it may also induce a squint or “turn” in the eye

A child with hyperopia has a small eye and a flat cornea and has to make an extra eff ort at using the focussing muscles which sometimes causes the eyes to turn in, inducing a squint

There is often a history of hyperopia in a family, usually one of the parents however, as with astigmatism, it may be also an uncle, aunt or grand parent who has this condition. All siblings and cousins must be examined by an eye doctor at as young an age as possible

REFRACTIVE ERRORSMYOPIA, ASTIGMATISM AND

HYPEROPIA

Hyperopia is long-sightedness and a child will be prescribed magnifying lenses for this condition but only if their sight is being threatened or if they have an associated squint

You can recognise a child who has hyperopia by noticing that their eyes are magnified behind their glasses

HYPEROPIA

This means that the sight in one of the eyes does not reach its full potential, even when wearing the glasses. If one eye has a diff erent focus from the other or if there is a squint or “turn” than “lazy eye” can occur.

It is often obvious if a child has a squint of “turn” and parents realise that some thing is wrong.

However if one eye is out of focus and there is no squint then the condition is not obvious to the parents.

Often there is a family history of “lazy eye” so you should always enquire with the older generation about this possibility

AMBLYOPIA OR “LAZY EYE”

A squint or “turn” in an eye can cause it to become amblyopic or “lazy”

Astigmatism or hyperopia (long sightedness) can also cause “lazy eye”

Even when corrected with glasses the eye may remain “lazy” and this is because it is not the actual eye that is “lazy” but the visual area of the brain which is at the back of the head. Due to the “turn” or the blurred vision the brain has not been trained to see clearly on that side.

There is treatment for lazy eye but early diagnosis is crucial to the success of this treatment.

CAUSES OF “LAZY EYE”

If your child is diagnosed with “lazy eye” (amblyopia) then usually a pair of glasses are prescribed in the fi rst instance. If the glasses do not adequately improve the vision after a few months than patching is introduced.

The good eye (not the lazy one) is patched for a number of hours on most days so that the part of the brain that receives images from the “lazy eye” can develop and become fine tuned.This improves the vision in that eye.

The number of hours of patching depends on the age of the child and the density of the amblyopia (“laziness of the eye”)

TREATMENT OF “LAZY EYE”

Here is an example of children who have been patched for treatment of “lazy eye”. The good eye has been patched and they are looking through the “lazy eye”.

The glasses correct their long sightedness (hyperopia)

PATCHING

A “turn” or squint in the eye can be very obvious or very subtle. If it is noticed it is important that it is diagnosed by an eye doctor and treated at an early stage. Never delay diagnosis and treatment, as postponing this can lead to permanent reduction in vision in the aff ected eye.

This baby has an obvious squint in his right eye and because he has been brought for diagnosis and treatment at a very young age his prognosis is excellent.

SQUINT OR “TURN” OF THE EYE

The majority of squints in children are “turned in” squints otherwise known as convergent squints or esotropia. Occasionally a “turned out” squint or a vertical squint occurs

The “turned in” or convergent squint can either be a congenital misalignment of the eyes i.e. the child is born with a turned in eye or it can be due to long sightedness (hyperopia). It can also be due to a combination of these causes

Most “turned in” squints can be treated with glasses and patching. Some need to be treated surgically where the muscle attachments of the eye are readjusted under anaesthesia. Your eye doctor will advise of what is best for your child

TYPES OF SQUINT (“TURN” IN THE EYE)

Convergent or “turned in” Squint sometimes called esotropia

Divergent or “turned out squint sometimes called exotropia

SQUINTS OR TURNS