Amblyopia (Lazy Eye)
A child’s eyes need regular, equal use to develop normal vision. Poor vision in an eye that did not get enough use during childhood is called amblyopia (“lazy eye”). Treatment during early childhood can usually reverse amblyopia. Treatment after childhood is rarely helpful. A child with amblyopia who does not get treatment will probably have poor vision for the rest of his or her life.
Any condition that prevents a child’s normal use of one or both of her eyes can result in amblyopia. Normal vision develops rapidly during the first two years of life and continues more slowly until about the age of 9. During that time, a child’s eyes and brain learn how to work together to see.
Practice is the most important part of this learning process. Constant use of both eyes gives a child’s eyes and brain the practice they need to develop eyesight. If there is a problem with vision in one eye, visual signals from that eye may never reach the brain. This disrupts the learning process, and the brain stops developing normal vision for that eye
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. Children in a family with a history of amblyopia or misaligned eyes should be checked by an Ophthalmologist early in life.
Amblyopia has three major causes:
- Strabismus (misalgined 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.
- 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 and requires careful measurement of vision.
- Cloudiness (in the normally clear eye tissues)
An eye disease such as cataract (a clouding of the eye’s natural 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 very rare, but serious.
How is it diagnosed?
It is not easy to recognise amblyopia. A child is usually not aware of having one better 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 fixation between the two eyes.
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. Your ophthalmologist will also carefully examine the interior of the eye to see if other eye diseases may be causing decreased vision.
How is it treated?
To correct amblyopia a child must be made to use the weak eye. This is usually done by patching or covering the better eye, often for weeks or even 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 may be necessary. Occasionaly, amblyopia is treated by blurring the vision in the good eye with special eye drops or lenses to enable to child to use the amblyopic eye..
Your ophthalmologist can give you instructions on how to treat amblyopia, but it is up to you and your child to carry out this treatment. Children do not like to have their eyes patched, especially if they have been depending on that eye to see clearly. But as a parent you must convince your child to do what is best for him or her. Successful treatment mostly depends on your interest and involvement as well as your ability to gain your child’s cooperation. In most cases, parents play an important role in determining whether their child’s amblyopia is to be corrected.
Is loss of vision preventable?
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. Sometimes part-time treatment may have to continue until the child is about nine years of age. After this time, amblyopia usually does not return. If amblyopia is first discovered after early childhood, treatment may not be so successful.