Amblyopia or Lazy eye - Features, Diagnosis & Treatment
Lazy eye, termed amblyopia by your eye doctor, is an eye condition that results due to an error of development of vision in infancy or childhood, without any structural disease in the eye. The nerve pathways between the brain and the eye, called visual pathways, do not mature properly, when the vision stimulus from one eye is hazy as compared to the other. Over time, the brain “learns” to ignore this image, and begins to favor one eye which has the clear image. This decrease in vision is not correctable by glasses or contact lenses, or even refractive surgery.
Types of amblyopia or lazy eye are:
Stimulus deprivation amblyopia results when the vision of either eye is blocked due to any reason, during early childhood.
Strabismic amblyopia is caused by a misalignment of eye(also called strabismus or squint).
Anisometropic amblyopia is due to gross difference in the eye power prescription or refractive error of the two eyes
What is the treatment for lazy eye?
To treat lazy all attempts must be made to make the patient use the amblyopic eye. This, at least in children, can reverse the suppression of the image of the amblyopic eye by the brain.
The basic principles of lazy eye treatment include:
Remove the cause of amblyopia: The corrective measures include correction of squint (strabismus) or eyelid droop (ptosis), removal of cataract, and correction of refractive error with appropriate glasses or contact lenses.
Wear proper glasses or contact lenses, even if the vision is not improved by them. Wearing the correct power provides the brain with a clear image, thus reversing suppression of that eye.
Use the lazy eye more by occlusion therapy or patching the good eye. To force the brain to learn to use the lazy eye again, the ophthalmologists usually recommend either patching the good eye, or using dilating drops to blur the image of the good eye. Occlusion therapy is known to be effective until the age of eight to nine years, called the age of neuroplasticity. However, most doctors will advise a trial of occlusion even in older children. Also, this is why lazy eye must be diagnosed and treated as early as possible.
When should lazy eye be treated?
As discussed earlier, the window for lazy eye treatment is narrow. The earlier we start treatment, the better and faster are the results. This is why there is a great emphasis on screening of preschool children by a pediatric ophthalmologist to rule out lazy eye. Since these children usually cannot read, special techniques of vision have to be used to rule out lazy eye or amblyopia.
Any other causes of amblyopia also must be screened for, diagnosed and treated as early as possible to ensure proper development of the neural pathways and prevention of suppression. All children who need glasses must be prescribed the correct power, and encouraged to wear them regularly, even if there is no apparent benefit to the visual acuity at that point. These children must also be kept on regular follow up to ensure proper care and refractive correction.
Can lazy eye in adults be treated?
Earlier, it was thought that lazy eye in adults cannot be treated at all. Current studies, however, have shown that even teenagers and adults can benefit from amblyopia therapy. Since the therapy is not surgical or invasive, and also does not cost much, it is rational to give it a try even in adults, along with prescription of the appropriate glasses.
What about laser vision correction or LASIK for lazy eye?
In certain special circumstances, laser surgery for vision correction in the amblyopic eye, may be advised by the treating doctor, especially in case of anisometropic amblyopia. In these patients, wearing glasses is often difficult due to the different powers in the two eyes. The relatively high power glasses in one eye only, can often cause strain, double vision and headaches. Also, the high power lens on one eye is heavier than the other, resulting in skewed or tilted glasses that are not comfortable on the bridge of the nose. LASIK can improve vision without the need for glasses, but only to the extent that is corrected by the spectacles, making the individual less dependent on glasses. After this, amblyopia therapy can be instituted as usual.
Who is the best doctor for treating lazy eye?
All eye specialists or ophthalmologists are trained to diagnose and mange amblyopia, but pediatric ophthalmologists are especially trained to take care of the eye diseases on young children and infants. Since squint is usually seen in children, these specialist eye surgeons are also trained especially to take care of squint or strabismus.
It is important to find for your child an eye care professional who is well trained, and also, who is friendly with children, so that the child can be motivated to wear glasses and agree to patching of the good eye regularly.