Amblyopia, commonly known as lazy eye, is the eye condition noted by reduced vision not correctable by glasses or contact lenses, and is not the result of any eye disease. The brain, for some reason, does not fully acknowledge the images seen by the amblyopic eye. This almost always affects only one eye, but may manifest with reduction of vision in both eyes. It is estimated that three percent of children under six have some form of amblyopia. According to researchers at New York University’s Center for Neural Science, amblyopia results from developmental problems in the brain.
What causes lazy eye (amblyopia)?
Amblyopia usually starts when one eye has much better focus than the other eye. For example, one eye might be very farsighted or have a lot of astigmatism, while the other does not. When a child’s brain is confronted with both a blurry image and a clear one, it begins to ignore the blurry image. If this goes on for months or years in a young child, the vision in the eye that sees the blurry image will deteriorate.
Another cause of amblyopia is squints (strabismus), which is an ocular misalignment, meaning that one eye turns inward or outward. This prevents the eyes from focusing together on an image and may cause double vision. To combat this, the child’s brain generally chooses to ignore the image from the deviated eye, causing the vision in that eye to deteriorate. It’s this misalignment of the eyes that leads some people to call amblyopia “lazy eye.”
In other cases, a child cannot see well in one eye because something blocks light from getting through, such as a cataract or a small amount of blood or other material in the back of the eye.
Lazy eye (amblyopia) is the poor vision due to incomplete visual development within the brain. The human brain requires visual stimulation to develop fully. Anything that interferes with clear vision in either eye between birth to 8 years of age, can cause amblyopia.
Early diagnosis increases the chance of successful treatment, as after the age of 8 years, visual impairment may become permanent. Conversely, if your child does not have amblyopia by age 8 years, then he/she is unlikely to develop it.
How do I know if my child has lazy eye?
Children with amblyopia often do not complain of poor vision, and a problem is sometimes first noted when vision in both eyes is tested (eg in school visual screening). Occasionally, parents will notice a squint (strabismus) when one eye appears to be misaligned. Under certain conditions (eg where there is strabismus, droopy eye lid, or obstruction to the visual axis), your doctor may need to screen your child regularly for amblyopia.
What puts my child at risk?
Your child is at a higher risk if he or she has:
High amounts of astigmatism, long-sightedness (hyperopia) or short-sightedness (myopia) Large differences in spectacle power between the two eyes Obstruction of vision by congenital defects such as droopy eyelid (ptosis), cataracts or other lesions in the eye Strabismus or squints where the eye that is misaligned is not usedWhat kind of treatments are available?
Firstly, if there is abnormal vision, the child needs to be given appropriate spectacles which needs to be worn all the time. Next, the child needs to be encouraged to use the lazy eye. This is usually done by patching or covering the good eye, often for several hours per day.
Treatment may take months, and even years, and is often more effective when started earlier. When amblyopia is detected too late (eg after the age of 8 years) it may not be possible to reverse the visual damage. It is therefore important that you have your child checked if you or the school health services suspects or picks up a potential problem.
