New amblyopia research shows that treatment with both eyes is better than patching alone!
For ages, the majority of amblyopia research and treatment has focused on two areas: the use of glasses to provide the clearest vision possible and the use of an eye patch to force the amblyopic (weaker) eye to see. Patching often worked well. But there are some reasons why patching alone often doesn’t work.
The problem is patching is two fold:
1) Patching is hard! (It can be like a form of torture for some patients.) Cover up your good eye and see everything blurry for hours on end. You are forced to use an eye that you are not comfortable using, without having any idea how to intentionally move or change focus in that eye. You are just supposed to figure it out. Patients resist patching, avoid visually demanding activities, get frustrated more easily, and often “cheat” or “peek” from behind their patch.
As the American Optometric Association’s Amblyopia Patient Care Guideline says, “Noncompliance with occlusion represents a significant factor in occlusion failures, especially in patients over 8 years of age in whom up to 50 percent noncompliance is common.”
2) Patching alone does not solve the underlying problem. Amblyopia is not a situation where one eye is normal and the other is lazy. Amblyopia is a situation where one eye is struggling to focus clearly or stay pointed in the right direction, and the other eye is a bully. Yes, literally. The bully eye steals the brain connections from the weaker eye and uses them for itself. So while patching helps the weaker eye reinforce brain connections and see more clearly, it does not teach the bully eye to be nice. It just means the weaker eye can stand up for itself.
For example, it is like taking a right-handed child and putting the right arm in a cast for 8 hours a day for a year or so. Without helping them learn to hold a pencil, button clothes, or eat with their left hand – what will they do? They will avoid activities that need them to use their hands because they are clumsy. And when the cast is off, the right hand still takes over. What about activities that use both hands together, like tying a shoe? They still haven’t really developed equal strength between both hands, fine motor control of the left hand, or any coordination with the right hand.
The same happens with binocular vision (using both eyes). Patients who only use patching, often find the amblyopia returns when the patching stops, because they never learned to use both eyes together. It’s easy for the eyes to slip back into old (bad) habits. More patching? Again? At some point, it would seem easier to just give up and accept less than ideal vision.
But there is good news! I have written about some exciting developments in amblyopia research before, such as the amblyopia Tetris study, which showed that amblyopic treatment not with patching, but by treating both eyes (binocular), improved amblyopia in adults.
I am happy to report that there has been a recent spate of studies concerning the binocular treatment of amblyopia. Optometrists have felt for years that amblyopia was primarily a binocular phenomenon, and therefore required binocular solutions. We have anecdotally observed 1) faster treatment of amblyopia with binocular vision therapy and 2) greater regression with patching alone versus patching plus some form of binocular therapy. We are very excited to see excellent recent research that supports this view, mostly done by ophthalmologists and neuroscientists.
Be warned, gentle reader, the following are quotes directly from the published scientific papers on amblyopia research. I will summarize below each passage. Emphasis mine.
Converging evidence points to the pivotal role of decorrelated binocular experience in the genesis of amblyopia and the associated residual deficits. These findings suggest that a new treatment approach designed to treat the binocular dysfunction as the primary deficit in amblyopia may be needed. Prog Retin Eye Res. 2013 Mar; 33: 67–84.
What this means: It turns out that amblyopia might be due to a problem of both eyes, not just the “lazy” one. We should find a way to treat both eyes together.
…dichoptic perceptual learning, designed to strengthen binocular combination by reducing suppression, improves both stereopsis and acuity in adults and children with amblyopia…. As a whole, these results lead us to question the prevalent view that amblyopia is primarily a disorder of monocular vision and should be treated accordingly with monocular occlusion. If we are open to the possibility that binocular interactions lie at the heart of amblyopia, then we could be at the threshold of a new age of therapeutic interventions that don’t involve patching the fellow fixing eye. Ophthalmic and Physiological Optics Volume 34, Issue 2, pages 146–162, March 2014
What this means: Yep. Amblyopia is a problem of both eyes. And treating both eyes is better. And that means that hours of patching one eye might soon be a thing of the past. And vision therapy is the way of the future for patients of any age.
Update: You can see some examples of modern amblyopia video game treatment in this post.
Onward and Upward!