I’ve never liked the term lazy eye, because it’s so misleading! Why do I say that? Well, let’s talk about what amblyopia is first.
Amblyopia is a condition that occurs when the communication between the eye and the brain aren’t developing properly. This can occur for a number of reasons:
- Differences in prescription between two eyes.
- Larger prescription in both eyes.
- One or both eyes not pointing straight ahead.
- An eyelid drooping down or a cataract forming early (essentially something blocking the vision).
These issues cause the eyes not to work together properly and unfortunately, the brain won’t develop the pathways between the eye and brain as well as it should.
Let’s take the first cause I mentioned above as an example. Let’s say a 6 year old boy comes in for an exam. His mother and father think everything is fine, but he failed a school vision screening. School might seem like it’s going fine for him at this point though, as of course he’s young and children learn at different paces.
At this age, children should be able to see 20/20 without any glasses or contacts in each eye. When we check this young man’s vision, he’s only seeing 20/60 in his right eye, but his left is 20/20.
So what gives? Why can he see so well in his left eye, but not his right? Well, after we check his glasses prescription, then dilate his eyes and recheck it while he’s dilated, we come to find out that he has a large prescription in his right eye! At this point we have found out his right eye is quite farsighted and his left eye is only a little farsighted. We can get his vision back to 20/40 in the right eye, but it takes quite a bit of effort.
So let’s take a look at some numbers for prescription to try to help us understand why there is such a difference.
Let’s say his prescription comes out to be RT: +6.00 Sph LT: +1.00 Sph
Obviously, 6 is bigger than one. With a prescription like that, children can actually force their focusing system to see more clearly through each of those powers. So why can’t our patient see better than 20/40?
The reason for this is that the brain is essentially lazy. Remember how I said that I think the term lazy eye is misleading? This is the reason! It’s the brain’s fault. The eye is perfectly healthy and structurally sound, but because it has a higher prescription, the brain doesn’t want to deal with the extra effort to focus the right eye.
So why can’t the brain just focus each eye to the right power to be clear? In most cases, it’s a good thing for the eyes to be tied together with the brain. This way, they can work together and provide better vision.
This is one of the few instances where this can cause a problem. Because the eyes have to focus equally, the brain chooses to focus the left eye and right eye both to the power of 1.00. This leaves the right eye with a power of +5.00 that is uncompensated for and therefore blurry.
Because the right eye is constantly blurry, the pathways between the right eye and the brain don’t develop properly and the child is left seeing blurry.
Here’s an analogy to make it a little simpler – imagine the connection between the eye and the brain like a highway. In this case, the left eye is a 5 lane super highway with the speed limit set at 70 MPH. You can fly down that highway quickly and efficiently!
Now imagine that the right eye’s pathway is more like a gravel road. Sure, you can go down that road, but it’s going to be bumpy and slow. Which path do you think the brain is going to choose? Clearly the one with the fastest speeds! This is why the vision in that eye won’t develop as planned, because if the vision doesn’t develop by a certain age, it will unfortunately never develop.
So how do we find it and treat it?
Unfortunately, pediatricians aren’t equipped to measure for this as accurately as eye doctors would like. Many children slip through pediatrician and school screenings without any sign of the condition until they are around 9 or 10 years old, sometimes later.
The best method of treatment is prevention! We can often find this condition in patients when they are anywhere from 6 months to 4 years old and get them treated rather painlessly (the pain is more on the parents end than the child’s end, I’ll explain why soon!).
If we catch it early on, under the age of 4, then we are often able to prescribe a pair of glasses for full time wear and monitor your child for improvement over the next year until they reach 20/20.
But my child is now 10 and has never had an exam. How do we treat them for amblyopia now?
This is a little tougher, but not impossible. If we have a case, like the one I mentioned above, we can prescribe a pair of glasses for your child and have them start wearing them full time. Here’s where things can get a little more painful for the parents.
In cases like this in order to help the worse seeing eye improve, we have to penalize the better seeing eye. So our patient is seeing RT 20/40 LT 20/20 with his new glasses. In this instance, we would have your child wear an eye patch over his left eye for 2 hours per day or a total of 14 hours per week. This can be a bit tougher to accomplish if the child is fighting it, but it’s a necessary step to improve their vision.
This will force the brain to begin working with the right eye and the goal is that within 6 months, he’ll improve to around 20/25. By one year, if treatment is consistent, the hope is he would be seeing 20/20!
What happens if we don’t treat the amblyopia?
Depending on what study you quote, if amblyopia is not treated by 12, 14, or 17 years old, it is set where it is and improvement is difficult, if not impossible. In my own experience, I do agree that it is much easier to treat for 12 and under, but even in motivated teenagers, we do see improvement if they adhere to the recommendations to wear their glasses and do their patching therapy. In some cases, we will refer our patients out to a vision therapy specialist who can work with more active therapies to try to help improve binocularity (meaning helping both eyes to work together better).
Conclusion
You never know what’s going on with your child’s eye unless you bring them in for an appointment. The sad truth in these cases is that the children don’t know to say something is wrong when there isn’t any pain. To them, this is how they have always seen and they just assume that everyone sees the same way!
We recommend all children have their first examination between 6-18 months of age, then between 3-4 years of age, then yearly starting at 5 years old. Give our office a call today if you’d like to get your children scheduled! We are happy to see them any time!
-Dr. Nick