Amblyopia, also known as "lazy eye," is reduced vision - uncorrectable with lenses - in an eye that has not received adequate use during early childhood. There is no visible anatomical defect.
Causes of Amblyopia
Amblyopia has many causes. Most often it results from either a misalignment of a child's eyes, such as crossed eyes (strabismus), or a difference in image quality between the two eyes (one eye focusing better than the other, also known as anisometropia). In both cases, one eye becomes stronger, suppressing the image of the other eye. If this condition is not treated in early childhood, the weaker eye may become permanently impaired. With early diagnosis, amplyopia can be treated and loss of vision prevented. Listed here are the most common causes of Amblyopia.
- Strabismus (eyes not aligned straight)
- Congenital cataract (clouding of the lens in an infant)
- Uncorrected high near-sightedness (myopia) or far-sightedness (hyperopia) in both eyes
- Uncorrected high myopia or hyperopia in one eye (one eye focuses differently from the other)
- Severe ptosis (droopy eyelids)
Why Does Amblyopia Develop?
Amblyopia develops because when one eye is turned, as in strabismus, and therefore two different pictures are sent to the brain. In a young child, the brain learns to ignore the image of the deviated eye and see only the image of the better eye. Similarly when there is difference in refractive power between the two eyes, the blurred image formed by the eye with greater uncorrected power is avoided by the brain. A moderate or high degree of refractive power present in both eyes, when not corrected early and adequately, results in amblyopia. In order that the retina may register an object, it needs adequate light and visual stimulus. When these factors are absent, as in the presence of cataract in an infant, amblyopia also results.
Symptoms
Eye turning in, out or up
Closing one eye (particularly in bright sunlight)
Squinting
Headaches or eyestrain
Treatment
Amblyopia can often be reversed, or at least reduced, if it is detected and treated early. Cooperation of the patient and parents is required to achieve good results. If left untreated or if not treated properly, the reduced vision of amblyopia becomes permanent and vision cannot be improved by any means.
The most effective way of treating amblyopia is to encourage the child to use the amblyopic eye. This can be achieved by:
- Prescribing proper glasses to maximize and equalize the vision of both eyes
- Covering or patching the good eye to force use of the amblyopic eye
- Eye drops, such as atropine, to blur the vision in the good eye
- Removal of cataract when indicated
- Surgery, when amblyopia is accompanied by strabismus and is unresponsive to conservative treatment.
When occlusion (patching) is decided upon, the treatment may vary from a few hours to months or even years depending upon the age of patient, the type and severity of amblyopia, and the response. Older children can do reading exercises at home while patching the normal eye. Those patients who are patching their eyes need periodic follow-up, which is scheduled with your ophthalmologist.