Amblyopy or Lazy Eye
What is Amblyopy or Lazy Eye?
Amblyopy is the uni or bilateral decrease in visual acuity without there being any detectable organic cause. It happens during the critical period of visual development, normally up to the age of 12 and affects 4% of the population.
What causes it ?
There are various causes, all of them capable of leading to Lazy Eye. Among them we have the following in order of frequency:
- Strabismus (crosseyed) : This happens when both eyes do not look straight ahead so that the image in one eye is centered on the fovea ( the area of the retina for maximum vision ) whilst the other eye projects the image onto another area of the retina of lesser value.This makes the child develop adaptive mechanisms which overide the image from the anomalous eye so as not to see double.
- Ametropy This means that there is a refractive defect in both eyes. It happens when there are high hypermetropias ( > 4 dioptres) or astigmatism of > 3 dioptres. If this is not corrected the information which the brain receives will not give a sharp image.
- Deprivation, This occurs when a cataract, other opacity in the medium or a drooping eyelid, prevents the child from receiving visual stimulous correctly in this eye.
What are the symptoms of Amblyopia?
A child who doesn’t see very well is often goes unnoticed by parents and we can only detect it by way of a detailed ophthalmological exploration. Nevertheless, there are some symptoms such as difficulty to see well at a distance, eye deviation, screwing up of eyes, drawing up close to the television, headaches and difficulty in calculating the distance of object since there is no real sensation of depth
How can we diagnose a case of Amblyopy or Lazy Eye ?
By way of a complete ophthalmological examination. Fundamentally there will be a difference in the vision of both both eyes when we measure it with an Optotipo ( a system to measure acuity. ) If the child is young and we cannot test his sight, there are indirect signs such as covering up the good eye and the child, not feeling comfortable, will try to take the eye patch away or cry. The definitive test would be to dilate the pupil and see if he has a high refractive deficit ( high myopia, hypermetria, or astigmatism.) If the child has latent or evident strabismus we can pinpoint that with specific tests.
Is it possible to prevent Lazy Eye and what happens if it is not treated in time?
It is advisable for all children under 3 years old to have an ophthalmological examination, a maximum age if there is a family history of lazy eye, strabismus, or any other ocular pathologies. Exploration is difficult at such an early age on account of the poor or nonexistant colaboration from the patient. However, if the ophthalmologist is well acquainted with this condition, he will manage to make a correct diagnosis in all cases.
If this disorder is not diagnosed and treated in time, if at all possible before the age of 3, given that visuial maturity is reached at an early age ( before 12 years old ) we could find that, if in the future the child has an ocular problem in the good eye, his vision will be deficient for the rest of his life.
How is Lazy Eye treated ?
Treatment is based on first determining the cause of lazy eye and correcting it by suitable means. Colaboration by the parents is essential as they must understand the importance of acheiving the best possible visual acuity. Early diagnosis and treatment must be carried out together with information for the parents about the long and laborious treatment entailed which must not be suspended until indicated by the ophthalmologist, normally when the child is more than 12 years old.
We must correct the cause of lazy eye which can vary from correcting an optical defect or removing cataracts, to correcting strabismus.
Along with treatment for the cause, treatment for amblyopy is based on occlusion of the good eye in order to force use and development of the lazy eye. Occlusion is carried out by applying ocular patches periodically, depending on the degree of amblyopy, and always assessed by the ophthalmologist. An alternative to patches, if the child cannot tolerate them, would be to use eye drops which paralyse focussing in the good eye to cause blurred vision, thereby obliging use of the bad one.
Ideas to bear in mind would be to say how important it is to examine children before they are 3 years old in order to detect a possible amblyopy which must always be done by an ophthalmologist. Treatment must be started as soon as possible. This must include cooperation from the parents, well informed about the importance of following to the letter every indication given by the ophthalmologist, and continuing it without fail in every case until the child is 12 or more.
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