Amblyopia

AMBLYOPIA

What is Amblyopia?

How to Identify the good,the bad and the ugly signs of Amblyopia?

Amblyopia is decreased vision in one or both eyes due to abnormal development of vision in infancy or childhood.  In amblyopia, there may not be an obvious problem of the eye. Vision loss occurs because nerve pathways between the brain and the eye aren't properly stimulated. The brain “learns” to see only blurry images with the amblyopic eye even when glasses are used. As a result, the brain favors one eye, usually due to poor stimulation of vision in the other eye. Another word for amblyopia is often “lazy eye.” It is the leading cause of vision loss among children.

WHAT CAUSES AMBLYOPIA ?

The human brain learns and adapt to visual stimulation with time. Any deprivation in this neural stimulation makes the human brain think it’s normal and hence adapt. The longer the deprivation the more difficult it gets to correct the anomaly.

Normal vision develops during the first few years of life. At birth infants, have very poor vision, however as they use their eyes the vision improves because the vision centers in the brain are developing. If infants are not able to use their eyes from various reasons the vision centers do not develop properly and the vision is decreased despite normal appearance of the structures of the eyes.
The most common cause is refractive error in one or both eyes that is not corrected early in childhood resulting in poor development of the visual function in the affected eye/s. This is called refractive amblyopia.
Another common cause is strabismus or eye misalignment. This is called strabismic.
Rarely there is a structural anomaly that impairs the visual function like a droopy eyelid or opacity in the visual axis like cataract or corneal scar. This is called deprivation amblyopia.
Multiple causative factors can coexist.

What is strabismic amblyopia?

Strabismic amblyopia develops when the eyes are not straight. One eye may turn in, out, up or down. When this happens, the brain begins to ignore, or “turns off” the eye that is not straight and the vision subsequently drops in that eye.

What is deprivation amblyopia?

Deprivation amblyopia develops when cataracts or similar conditions “deprive” young children’s eyes of visual experience. If not treated very early, these children never learn to see very well and can have very poor vision. Sometimes this kind of amblyopia can affect both eyes.

What is refractive amblyopia?

Refractive amblyopia happens when there is a large or unequal amount of refractive error (glasses strength) between a child's eyes. The brain learns how to see well from the eye that has less need for glasses and does NOT learn to see well from the eye that has a greater need for glasses. The vision problem may be invisible because the child does not complain of blurry vision.  The child sees well with the better seeing eye.  Additionally, the amblyopic eye may not look any different from the normal seeing eye. Therefore, parents and pediatricians may not think there is a problem because the child’s eyes look normal.   For these reasons, this kind of amblyopia in children may not be found until the child has a vision test. This kind of amblyopia can affect one or both eyes and can be best helped if the problem is found early.

How is amblyopia treated?

In amblyopia early detection means early prognosis.See your Opthalmologist/Optometrist as early as possible.

One of the most important treatments of amblyopia is correcting the refractive error with consistent use of glasses and/or contact lenses. Other mainstays of amblyopia treatment are to enable as clear an image as possible (for example, by removing a cataract), and forcing the child to use the weaker eye (via patching or eye drops to blur the better-seeing eye).

 

When should patching be used for amblyopia treatment?

1.Patching is a very effective way of treating amblyopia as it allows the weaker eye to get stronger, however it is very hard to make a young child wear a patch. It needs a lot of effort, persistence and encouragement form the parents. The younger the child is, the faster it works in improving the vision, therefore the parents should be persistent and encouraging and not wait until the child is old enough to want to patch. An ophthalmologist should regularly check how the patch is affecting the child’s vision.

2. Sometimes the stronger (good) eye can be “penalized” or blurred to help the weaker eye get stronger. Atropine drops will temporally blur the vision in the good eye and work as a great alternative to patching in selected cases. This forces the child to use the weaker eye. For mild to moderate degrees of amblyopia, studies have shown that patching or eye drops may be similarly effective. Your pediatric ophthalmologist will help you select what treatment regimen is best for your child.

3.There is no surgery to improve the vision for amblyopia. Surgery can be performed to straighten misaligned eyes such as crossing. Surgery to make the eyes straight can only help enable the eyes to work together as a team. Children with strabismic amblyopia still need close monitoring and treatment for the amblyopia, and this treatment is usually performed before strabismus surgery is considered.

Children who are born with cataracts may need surgery to take out the cataracts. After surgery, the child will usually need vision correction with glasses or contact lenses and patching.

What is Vision Screening?

Vision Screening is strongly recommended by the American Academy of Pediatrics (AAP) over the course of childhood to detect amblyopia early enough to allow successful treatment. Pediatricians check newborns for red reflex to find congenital cataracts. Infants are checked for the ability to fix and follow and whether they have strabismus. Toddlers can have their pupillary red reflexes tested with a direct ophthalmoscope (Brückner Test) or by instruments that identify a significant refractive error that needs correction to prevent amblyopia. When children can consistently identify objects either by reading or by matching, the acuity of each eye (with the non-tested eye patched) is screened to identify amblyopia.