Amblyopia occurs when the brain and eye do not work together properly. The eye itself is structurally normally but the vision in that eye is reduced. It commonly affects only one eye but can occur in both. Amblyopia is the most common cause of sight impairment in children and occurs in about 3 in 100 children. If it is not treated early the amblyopia usually persists into adulthood.
There are several different types of amblyopia, which are classified according to what cause them:
- Strabismic: the eyes are not straight e.g. one or both of the eyes may be crossed in (esotropia) or turned out (exotropia)
- Deprivation: occurs when the eye does not receive an adequate amount of visual stimulation e.g. cataract
- Refractive: one eye may be more nearsighted, farsighted or astigmatic than the other. This type of amblyopia is usually only picked up when the child has a vision test.
The visual system undergoes rapid development in the first nine years of life and it is during this time that the complex connections between the eye and the brain are developed. The prognosis for better or normal vision in the amblyopic eye is good if the eye is treated early thus highlighting the importance of early visual screening in young children.
Treatments that may be available
- Refractive: the child will benefit from the early use of correction of the near or farsightedness by wearing glasses or contact lenses.
- Deprivation: if the amblyopia is caused by 'deprivative' conditions such as cataract, the surgical correction of this should be strongly considered and discussed in detail with the parents to prevent the eye from becoming amblyopic.
- Strabismic: this treatment focuses on strengthening the amblyopic eye. This forces the child to use the weaker eye more by two main methods:
- Atropine: this is an eye drop that is placed in the stronger eye and temporarily blurs the vision of the eye so that the child will use the weaker eye to see. Atropine also helps with the visual development of the weaker eye
- Patching: this method should only be done under the recommendation of an ophthalmologist. It involves placing a patch over the child's stronger eye for a period of weeks to months. This encourages the child to use their weaker eye and stimulates the development of the visual connections of the amblyopic eye to the brain.