Children’s eye health and choosing glasses

1. Medical Optics
CHILDREN’S EYE HEALTH
AND CHOOSING
GLASSES FOR YOUR
CHILD

2. COMMONEST EYE CONDITIONS IN
CHILDREN
The 3 commonest eye conditions in chi ldren are the fol lowing
1. Refractive errors (myopia, astigmatism and hyperopia)
2. Amb lyopia or “ Laz y E ye ”
3. S qu i nt o r “ Tu rn” o f t h e eye
We wi l l now discuss these three conditions in more detail

3. REFRACTIVE ERRORS
MYOPIA, ASTIGMATISM AND HYPEROPIA
A re f ra ct ive e rro r c a u s es b l u rring i n a c h i ld’ s v i s i o n a nd i f
significant it should be corrected by wearing glasses.
In most cases it is impor tant for your chi ld to star t wearing the
glasses at the earl iest oppor tunity as the visual par t of the
brain only develops properly if it is presented with a wel l
focused clear image from the eyes.
Fa i l ure to d o t h i s wi l l re s u lt i n amb lyo pia o r “ l a zy eye ” wh i c h
c an b e re c t i fied to s ome d e g ree by “ p at c hing ”

4. REFRACTIVE ERRORS
MYOPIA, ASTIGMATISM AND HYPEROPIA
Myopia me ans “ s h or t s i g hted” and you r c h i l d c annot s e e
properly in the distance but is able to read clearly
It sometimes takes a whi le for parents to become aware of this
condition as it develops slowly as the eyes grow. Of ten the
teacher wi l l say that your chi ld needs to sit near the front of the
class to see the blackboard or you might notice that your chi ld
sits near the T.V. to see it clearly
Myopia is the easiest refractive error to treat and rarely causes
amb l yopi a or “ l azy eye ”. A p ai r of g l as ses i s al l t h at i s u s u ally
required. The glasses should be worn 90% of the time

5. MYOPIA
You can see that this l ittle girl has myopia by looking at her
glasses. Her eyes appear smal ler behind the lenses. This is
par ticularly obvious when looking at her right eye – you can see
the edge of her cheek within the lens

6. REFRACTIVE ERRORS
MYOPIA, ASTIGMATISM AND HYPEROPIA
Astigmatism i s wh e n t h e f ront of t h e eye or “ c orne a” i s
shaped l ike the sur face of a rugby bal l , instead of the normal
s o c c e r b a l l o r “ s p h erica l” s h a p e
This means that there are two focal planes presented to the
retina (fi lm at the back of the eye) and your chi ld sees a blurred
image rather than a clear image
A s t i gmat ism i s a l e a ding c a u s e o f “ l a z y eye ” a nd i f t h e re i s a
history of this condition in the fami ly then al l your chi ldren
should be examined by an eye doctor at an early age

7. ASTIGMATISM
There are three types of astigmatism i .e. myopic astigmatism,
hyperopic astigmatism or mixed astigmatism
It is not possible to tel l if a chi ld has astigmatism by looking at
their glasses

8. REFRACTIVE ERRORS
MYOPIA, ASTIGMATISM AND HYPEROPIA
Hyperopia me ans “ l ong - s igh ted” and t h i s c ond i t i on c an al s o
c a u s e amb l yo pia o r “ l a z y eye ” . I n a d d i ti o n i t may a l s o i nd u c e a
s qu i nt o r “ t u rn” i n t h e eye
A chi ld with hyperopia has a smal l eye and a flat cornea and
has to make an extra ef for t at using the focussing muscles
which sometimes causes the eyes to turn in, inducing a squint
There is of ten a history of hyperopia in a fami ly, usually one of
the parents however, as with astigmatism, it may be also an
uncle, aunt or grand parent who has this condition. Al l sibl ings
and cousins must be examined by an eye doctor at as young an
age as possible

9. HYPEROPIA
Hyperopia is long-sightedness and a chi ld wi l l 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 chi ld who has hyperopia by noticing that
their eyes are magnified behind their glasses

10. AMBLYOPIA OR “LAZY EYE”
This means that the sight in one of the eyes does not reach its
ful l potential, even when wearing the glasses. I f one eye has a
d i f ferent fo c u s f rom t h e ot h e r o r i f t h e re i s a s qu i nt o r “ t u rn”
t h a n “ l a z y eye ” c a n o c c u r.
I t i s o f te n o bv i o u s i f a c h i l d h a s a s qu i nt o f “ t u rn” a nd p a re nt s
real ise 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.
Of te n t h e re i s a f ami ly h i s tor y of “ l az y eye ” s o you s h ou l d
always enquire with the older generation about this possibility

11. CAUSES OF “LAZY EYE”
A s qu i nt o r “ t u rn” i n a n eye c a n c a u s e i t to b e c ome amb lyo pic o r
“ l azy ”
Astigmatism or hyperopia ( long sightedness) can also cause
“ l a zy eye ”
E ve n wh e n c o rre c ted wi t h g l a s s es t h e eye may rema in “ l a z y”
a nd t h i s i s b e c a use i t i s not t h e a c t u a l eye t h a t i s “ l a z y” b u t t h e
visual area of the brain which is at the back of the head. Due to
t h e “ t u rn” o r t h e b l u rred v i s i o n t h e b ra i n h a s not b e e n t ra i ne d to
see clearly on that side.
There is treatment for lazy eye but early diagnosis is crucial to
the success of this treatment.

12. TREATMENT OF “LAZY EYE”
I f you r c h i l d i s d i agnos ed wi t h “ l az y eye ” ( amb lyop ia) t h e n
usually a pair of glasses are prescribed in the first instance. I f
the glasses do not adequately improve the vision af ter 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 par t of the brain that receives
ima ges f rom t h e “ l a z y eye ” c a n d evel o p a nd b e c ome fi ne t u ne d .
This improves the vision in that eye.
The number of hours of patching depends on the age of the
c h i l d a nd t h e d e ns it y o f t h e amb l yo pia ( “ l a zine ss o f t h e eye ”)

13. PATCHING
Here is an example of chi ldren who have been patched for
t re a tment o f “ l a z y eye ”. T h e g o o d eye h a s b e e n p a t c hed a nd
t h ey a re l o o k i ng t h ro u g h t h e “ l a zy eye ”.
The glasses correct their long sightedness (hyperopia)

14. SQUINT OR “TURN” OF THE EYE
A “ t u rn” o r s qu i nt i n t h e eye c a n b e ve r y o bv i o u s o r ve r y s u b t l e.
I f it is noticed it is impor tant 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 af fected 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 excel lent.

15. T YPES OF SQUINT (“TURN” IN THE EYE)
T h e maj orit y of s qu i nt s i n c h i l dren are “ t u rne d i n” s qu i nt s
otherwise known as convergent squints or esotropia.
Oc c a s i o nally a “ t u rne d o u t ” s qu i nt o r a ve r t i ca l s qu i nt o c c u r s
T h e “ t u rne d i n” o r c o nve rg ent s qu i nt c a n e i t h er b e a c o ng e ni tal
misalignment of the eyes i .e. the chi ld 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
Mo s t “ t u rne d i n” s qu i nt s c a n b e t re a ted wi t h g l a s s es a nd
patching. Some need to be treated surgically where the muscle
attachments of the eye are readjusted under anaesthesia. Your
eye doctor wi l l advise of what is best for your chi ld

16. SQUINTS OR TURNS
Co nve rg e n t o r “t urn e d i n ”
Squint sometimes cal led
esotropia
Di ve rg e n t o r “ t urn e d o ut
squint sometimes cal led
exotropia