YOUR CHILD’S VISION: COMMON EYE PROBLEMS IN CHILDREN
A. AMBLYOPIA (also known as ‘lazy eye’)
Amblyopia occurs because the eye is not able to reach the full potential of its visual development as the eye is not used (in other words, neglected) by the child who prefers to use the other normal eye to see. This is because the image seen with the affected eye is not as clear as the normal eye and the child prefers to see with the normal eye.
Any disease which blurs or blocks the vision during childhood will result in amblyopia.
- Refractive errors which have not been corrected with spectacles
- Squints (the eye which is squinting will be neglected and become amblyopic)
- Congenital cataract (cataracts which have formed at birth although this is rare)
- Cornea scarring due to infection or injury (also very rare)
In order to reduce the possibility of amblyopia, it is important to diagnose the condition and intervene early. A child with amblyopia may have no visual complaints because the child may be using the other good eye which has normal vision. For this reason, it is absolutely vital a child (who is at risk) must be assessed using appropriate testing techniques and examined by an eye doctor, optometrist or orthoptist to screen for amblyopia.
Amblyopia can be reversed if the situation is detected early during the visual development period (until the age of 9 years). The earlier amblyopia is detected, the greater is the child’s chance of recovery. Once a child is diagnosed to have amblyopia, the first plan of action is to treat the underlying cause (if any) such as shortsightedness using spectacles or congenital cataract using surgery before starting amblyopia therapy.
Image source: huffingtonpost
The amblyopia therapy involves patching the good (i.e: normal) eye so that the amblyopic eye will be used by the child and hence stops it from being neglected. The duration for patching the normal eye varies between 1 to 6 hours per day depending on the regime used and the severity of the amblyopia. It is important to use the lazy eye during the patching period by doing hand-eye exercises such as drawing, copying and colouring.
Compliance with therapy is the single most important factor determining a successful outcome. It requires full cooperation of the child and parents as well as strict supervision of the eye doctor or orthoptist to ensure good results. Visual improvement can sometimes be measured after only 1 month of therapy. Patching can be stopped when the vision has improved to almost normal (the lazy eye can never reach 100% normal so at best 90% of normal can be considered excellent result), or when there is no further visual improvement especially when the child has reached 9 years of age.
B. SQUINTS (also known as ‘cock-eye)
Image source: Allaboutvision
Humans possess two eyes which give us binocular vision and hence the ability to judge depth and distance in 3-dimension. In the normal person, the 2 eyes are parallel to each other and move together when we look from one object to another.
Image source: SightMD
A squint is present when the 2 eyes are not aligned parallel to each other. When looking ahead, the squinting eye (or cock eye) is either deviated inwards or outwards and is known as a convergent or divergent squint respectively.
When a child has a squint, the vision in the squinting eye will be suppressed and the child will prefer to use the normal eye all the time. This will lead to amblyopia (lazy eye) in the squinting eye. Squints usually appear between the ages of 1-3 years.
Treatment of squints involves patching the normal eye to reverse the amblyopia (see treatment of lazy eye above) and then plan to perform squint surgery to align the eyes so that they become parallel again. Some squints do not need surgery and eye fusion exercises together with spectacles will be sufficient to treat the squint.
Successful treatment will allow the child to look normal (so that he/she will not be teased at school) and restore some degree of binocular vision for the child.