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Amblyopia

child with big glasses and amblyopia
What is Amblyopia ?

Amblyopia is a vision deficit state, where vision loss occurs in one or both of the eyes even after Glass or contact lens prescription by an Optometrists. The term Amblyopia is also known as the “Lazy eye state“. The vision loss can be partial in most of the cases of Amblopia .

Amblyopia is diagnosed in early childhood or in infants. One eye or both of the eyes are affected by amblyopia resulting reduced visual acuity. The most critical time for a child to suffer from amblyopia is below the age of 6.

The amblyopia is produced by certain factors that leads to visual disorder.If detected at early age, it can be treated with the visual correction Aids or curing the disease that is causing  the vision deprivation.

In a research conducted in Nepal Eye hospital from June 2006 to 2011 it was found, the prevalence of amblyopia is 0.7% in schooling children.

Signs and symptoms of Amblyopia :
The symptoms of the amblyopia is not noticiable but some parents can notice the diversion of the eye ball in their children. The diversion is also known as “Strabismus” or “ Squint”. If you ever see your child looking with a nodded head,or misalignment of the eye, it is the best time to go see an Ophthalmologist or an optometrist.

Some tips for the parents:   
 Parents can determine if their child has amblyopia. All you got to do is cover a single eye while he/she is watching tv or doing any stuffs.And repeat the similar with the other eye. If your child is bothered while you cover the eye, it means he/she has blurred vision in one of the eyes. You probably have covered the good eye which means other eye cant see properly.

But a simple test doesn’t define the state of the eye.you have to take your child to an ophthalmologists.

 What Ophthalmologists find while examining ?
  • The recognition visual acuity is more affected than resolution acuity.
  • Eye  squinting and lids are half closed to see better.
  • Visual acutity is less when tested with different vision charts.
What causes amblyopia ?
  • Strabismic Amblyopia :Prolonged squinting of a eye in child  results in uniocular suppression. The brain ignores the visual stimuli from the squiting eye to maintain clear vision of the other eye and prevent diplopia.  
  • Refractive Amblyopia : It includes three major cases. It is caused by the refractive error in the eye.Child can have different refractive status in both of the eyes. That can be either, Anisometropia, Isometropia or Astigmatism even after perfect alignment of the two eyes. 
  • Stimulation Deprivation :This happens when something impedes the light to reach retina.Congenital and traumatic cataracts, Corneal opacity, ptosis covering the pupil are the major cause of stimulation deprivation .
Note: Long hairs or fringe/ bangs doesn’t cause amblyopia unless the bangs are thick and obstructs light continuously to reach the eye.


Girl with bangs that doesnt cause amblyopia

Treatment: 
The treatment for amblyopia should be started as early as possible.younger child have better prognosis.

The American Optometric Association recommends “That all children have their first eye exam at 6 months of age, another exam at age 3 and a third exam prior to entering school to ensure vision is developing normally in both eyes and there is no risk of amblyopia”

glasses making the writing clearIn refractive error induced amblyopia, it is necessary to correct the errors with glasses or contact lens.However the patching of the good eye is must. It is done to force brain to pay attention to the stimuli of the amblyopic eye.

Treatment of strabismic amblyopia involves surgery to straighten the squinting eye that is followed by Patching in the good eye. Some orthoptics aid could help both eyes work mutually also known as Vision therapy.
Prosthetic contact lens can be an option if your child throws away the patch.But prosthetic contact lenses are costly and it needs contact lens examination and proper care of the eye.
Atropine drops can also be a substitute to the patch.Atropine eye drops cause the blur vision in one eye, forcing the other eye to work.It doesn’t require proper care of your child to notice if he/she is wearing the patch or not.But the atropine has its own side effects. Light sensitivity and paralysis of ciliary muscle due to long term use.

Any opacity in visual media like cataracts should be operated and opacified lenses should be removed.
changing of the cornea for corneal opacity.The blurr and opacified cornea of the recipient is changed by a clear donor cornea.

How is patching done ?
kids with amblyopia and patching done

Patching is done in the ratio of the age of the child to the Amblyopic Eye.
Example: If a child is 3 years of age, patching is done in the ratio of 3:1 i.e  3days in sound eye and  one day in normal eye.

Note: The amblyopic eye is also patched so as to prevent  amblyopia in the good eye due to regular patching of the good eye.


Duration and Start of the patching therapy:
Patching should be done as sooner as possible.It may last as long as the vision is not fully restored or the visual improvement doesn’t occur even after strictly practiced patching for 3 months from the start.


 References and notes:

  •  Atropine an effective alternative to patching for amblyopia. 
  •  Review of Ophthalmology. October 2003.
  •  Https://www.ncbi.nlm.nih.gov/pubmed/23584645