Amblyopia "Lazy Eye"
Protecting the vision of your child
‘Amblyopia’ or ‘Lazy eye’ is a disease that starts in childhood and causes poor vision. It typically happens when the developing brain of a child is deprived of good sharp vision for some reason.
Its a common problem affecting almost 5% of all children and frequently missed till adulthood when it becomes too late to treat. Since the treatment is easy, it is very important to screen all children for this problem
- What is the cause of “Lazy Eye”?
- Is it common? When should I suspect it in my child?
- How can it be detected in time?
How?
All babies are born with poor eyesight. As they grow older, the eyesight gradually improves due to development of the eye and the vision centers of the brain. Just as the brain learns how to use hands and feet, the brain also undergoes this training period to learn how to use eyes.
For proper development of vision, the brain needs signals of a clear, focused image that is same in both the eyes. If the image isn’t clear, or is not of the same clarity in both the eyes, the vision center doesn’t develop properly. This results in “Lazy Eyes” or Amblyopia.
Lack of image clarity which results in lazy eyes can be due to many causes but are most commonly due to 3 reasons.
- The most common cause is an unmet need for glasses. The child may have farsightedness, nearsightedness or astigmatism which is more in one eye than the other (anisometropic amblyopia). The brain develops a preference for the eye with better vision and the other eye becomes lazy.
- Another common cause is crossed eye or squint. When one eye is either turned in or out, the brain develops a preference for the other eye and the squinted eye becomes ‘lazy’.
- The third less common but important cause is the presence of cataract, glaucoma, corneal and retinal diseases.
If an eye is lazy, the child is not able to read the smaller letters of vision chart upto 6/6 even with the correct glasses or even after correction of any cross eye.
Who?
Amblyopia or 'Lazy Eye' happens in childhood and can only be treated during childhood
The above statement summarizes the importance of being vigilant about it in your child. It affects approx. 5% of kids and can easily go undetected even till late adulthood. Its not uncommon for doctors to see young to middle aged adults to accidently realize that the vision in one eye is very poor. Very commonly its detected during pre-employment health checks.
Every child should be suspected for amblyopia and screened for it. Just because the child seems normal with no vision deficit doesn't mean that both eyes are working normally and their is no ambyopia.
Prevention
Regular eye checkups. That's how easy it is. The importance of it can be judged from the fact that regular screening for vision in schools is an integral part of government's "National Programe for Control of Blindness" Each eye is to be checked 'individually' for ability to read the smallest letters on the vision chart (the 6/6 line). Start these checkup at 3 years of age and continue annually till atleast 10 years of age. In addition also get a checkup at 6 months of age to look for common congenital problems.
More Questions and Answers
Usually the vision checkup at school is done by a trained optometrist. You need to visit an eye doctor in some scenarios
- If the child is detected to have vision problem during routine school screening
- If the teacher at school notices vision problem and recommends an eye checkup
- If regular eye checkups are not being done at your child's school or you're not sure about the reliability of the checkup
- If you notice squint or cross eye
- If you notice that the child squeezes his / her eyes while watching TV
- If you notice that the child has a tendency to come very close while watching TV.
- If you have a family history of eye problems especially need for glasses
The primary purpose is to check for child's ability to read the smallest letters on the vision chart individually from each eye. In older kids its easier but can become tricky in the young ones.
The eye checkup may also involve a process called "cycloplegic refraction" or 'dilatation". This allows more reliable measurements to be taken. It also allows more thorough checkup of the internal structures of the eye. Its not required in all cases and your doctor will be able to guide you through the process. During the process eye drops are instilled in the eye to relax the internal eye muscles. Most of these dilating drops are stingy. So be prepared for resistance from the child. These drops also blurs the vision especially near vision for anything between 4 hours to 2 weeks depending on the drop used.
Amblyopia or 'Lazy Eye' can only be treated during childhood. It becomes more and more difficult after 6 years of age.
The basic principle of the treatment if to force the brain to use the lazy eye. The first step is to remove any cause of blurry vision with either spectacles, squint correction or by correction of any other disease. Sometimes this step is enough and the vision is corrected to 6/6. In others the second step is to prevent the brain from using the better eye. This can be done either by putting a patch over the eye (Patching) or by using eye drops such as atropine to blur the vision (Penalization).
The effect of the treatment is monitored by a monthly eye checkup and the treatment may be continued for many months to years. The success of the treatment depends on the age of the child, the cause of Amblyopia and most importantly the compliance of the patient. Younger children respond to treatment much faster.
There’s a small chance that ‘patching’ or ‘penalization’ can hurt the strong eye by causing laziness eye in the previously better eye. This condition is called 'Reverse Amblyopia'. Though very rare but this makes it important for the child to see their doctor often during the treatment. It is easily treatable by stopping the treatment for a few weeks. Once the vision stabilizes again, the treatment can be restarted
A more important problem is the social stigma and the psychological effect on the child. And that's where sensitization of the school staff and members of the family is important.
