A visual examination done at an early stage of child's developmental years will go a long way in detecting and treating a condition called 'lazy eye' or in medical parlance, 'amblyopia' which arises in many school-going children in India. 'Lazy eye' is a particularly tricky condition, as it does not manifest outwardly, and therefore, goes completely unnoticed, unless the child has an obvious squint.
What is a 'lazy eye'?
A baby's vision is poor at birth and develops over a period of time. Good eyesight requires that both eyes send same images in a clear and focused manner to the brain. Sometimes, for some reason, the child's central vision does not develop properly, one eye, or in some cases both the eyes, is not able to carry signals to the brain properly, as a result a blurred image is perceived.
The eye which has reduced vision is called the 'amblyopic eye'. Outwardly, the eye may look normal, and the parent may not even realize that the vision in it is diminished. The child tends to ignore the weak eye and use the good eye resulting in further deterioration of the amblyopic eye. If this condition is not detected and treated early, it can lead to blindness in the amblyopic eye.
Lazy eye is not caused by anatomical or structural defects of the eye, nor is it caused by any defect in the optic nerve. It is a deficiency in the visual pathway that carries signals from the centre of the eye to the brain.
What causes 'lazy eye'?
Amblyopia results from three main conditions, which are squint or cross-eyes, uncorrected or unequal refractive errors or as a secondary condition to cataract or drooping eyelid. In squint there is a misalignment of eyes, and the image at the back of the squinting eye is ignored by the brain. This eye than becomes lazy. Sometimes, a right eye may be far-sighted and the left, short-sighted; thus both eyes may have different qualities (unequal) of vision. In such cases, the worst eye may suppress images causing blurred vision in that eye.
How to treat amblyopia?
The treatment for amblyopia depends on the causes. In case of anisometropia or unequal refractive errors, prescription glasses can train the eyes to focus properly. But in case of unilateral amblyopia, where only one eye is lazy, patching is required. An adhesive tape is patched on the good eye to make the weak eye perform. Alternately, atropine drops can be put in the good eye to suppress it and let the weak eye take over. An eye doctor may also prescribe glasses with one lens opaque to blur the vision of the good eye. In the case of squint, the surgery may be called for. In addition, orthoptic exercises may be prescribed to exercise the eye muscles to improve vision.
The first few years of life are most important for eyesight. The vision fully develops by the time the child is 8 - 10 years. If amblyopia is detected within this critical period, it can potentially be reversed by treating the cause. An early intervention betters the chances of treatment and reversal of the lazy eye. If left undetected, the condition can lapse into a stage where vision is considerably reduced in both eyes, something called ametropic amblyopia.
In the child's developmental years, the parents unfailing square up on immunizations, nutrition requirements, and treatment of illnesses through routine check-up with the doctors, but one vital aspect of development often goes unmonitored. Even a regular dental check-up may be on the cards, but parents do not understand the importance of visual examination at an early stage.
Many parents come to know of their children's lazy eye when the class teacher sends a note asking them to have their eyes checked because they have difficulty reading from the blackboard. But, even by the time that the teacher notices or the child himself realizes it is too late. Pre-school children wearing glasses may elicit uncharitable comments from insensitive people, but they are certainly better off than older children, as they have more chances of reversing their visual deficiencies than those with uncorrected vision for long.
So don't wait till your child starts school before showing him to an eye doctor. It's best to get your child's eyesight tested as early as possible. Just one trip to the ophthalmologist in the child's early years should save him a lot of trouble and heartache, later on.