Amblyopia (Lazy Eye)
Amblyopia is commonly known as lazy eye. This should not be confused with squint. Amblyopia is poor vision in an eye that did not develop normal sight during early childhood. After the age of four years, the development of the part of the brain that processes vision is almost complete. If the brain has not received clear images from the weak eye, it would be difficult to improve the vision in this eye after the brain is completely developed. The eye is then said to be amblyopic or lazy.
What causes Amblyopia ?
Amblyopia is caused by any condition that affects normal use of the eyes and visual development. In many cases, the conditions associated with amblyopia may be inherited. Amblyopia has three major causes:
Strabismus (Misaligned Eyes)
Amblyopia occurs most commonly with misaligned or crossed eyes. The crossed eye "turns off" to avoid double vision, and the child uses only the better eye. The misaligned eye then fails to develop good vision.
Unequal Focus/Refractive Error
Refractive errors are eye conditions that are corrected by wearing glasses. Amblyopia occurs when one eye is out of focus because it is more nearsighted, farsighted or astigmatic than the other.
The unfocused (blurred) eye "turns off" and becomes amblyopic. The eyes can look normal, but one eye has poor vision. This is the most difficult type of amblyopia to detect since the child appears to have normal vision when both eyes are open.
Amblyopia also can occur in both eyes if both eyes have very blurred vision. This can happen when there is a high amount of nearsightedness, farsightedness or astigmatism.
Cloudiness in the Normally Clear Eye Tissues
An eye disease such as a cataract (a clouding of the eye's naturally clear lens) may lead to amblyopia. Any factor that prevents a clear image from being focused inside the eye can lead to the development of amblyopia in a child. This is often the most severe form of amblyopia.
How is Amblyopia diagnosed ?
It is not easy to recognize amblyopia. A child may not be aware of having one strong eye and one weak eye. Unless the child has a misaligned eye or other obvious abnormality, there is often no way for parents to tell that something is wrong.
Amblyopia is detected by finding a difference in vision between the two eyes or poor vision in both eyes. Since it is difficult to measure vision in young children, our ophthalmologist often estimates visual acuity by watching how well a baby follows objects with one eye when the other eye is covered.
Using a variety of tests, our ophthalmologist observes the reactions of the baby when one eye is covered. If one eye is amblyopic and the good eye is covered, the baby may attempt to look around the patch, try to pull it off or cry.
Poor vision in one eye does not always mean that a child has amblyopia. Vision can often be improved by prescribing glasses for a child.
How is Amblyopia treated ?
To correct amblyopia, a child must be made to use the weak eye. This is usually done by patching or covering the strong eye, often for weeks or months. Even after vision has been restored in the weak eye, part-time patching may be required over a period of years to maintain the improvement. Glasses may be prescribed to correct errors in focusing. If glasses alone do not improve vision, then patching is necessary
Amblyopia also may be treated by blurring the vision in the good eye with special eyedrops or lenses to force the child to use the amblyopic eye.
Amblyopia usually is treated before surgery to correct misaligned eyes, and patching is often continued after surgery as well.
If the ophthalmologist finds a cataract or other abnormality, surgery may be required to correct the problem. An intraocular lens may be implanted. After surgery, glasses or contact lenses can be used to restore focusing while patching improves vision.
Success in the treatment of amblyopia also depends upon:
- How severe the amblyopia is; and
- How old the child is when treatment is begun
If the problem is detected and treated early, vision can improve for most children. Amblyopia caused by strabismus or unequal refractive errors may be treated successfully during the first nine years of age. After this time, amblyopia usually does not recur.
What happens if it is left untreated?
Amblyopia patients should ideally be treated before the age of eight or nine. If amblyopia is not treated, several problems may occur:
- • The amblyopic eye may develop a serious and permanent visual defect
- • Depth perception (seeing in three dimensions) may be lost
- • If the good eye becomes diseased or injured, a lifetime of poor vision may be the result. It is a proven fact that the injuries are more common to the healthy eye in such people.
The ophthalmologists at Shekar Eye Hospital have experience in treating multiple types of amblyopia cases. By using the latest, international-standard equipment to test the eyes, we have been able to find the exact cause of the problem and treat very young children too.