The medical eye patch is the oldest and most common treatment for amblyopia. By covering, or occluding, the strong eye you force the brain to use the weak eye. By having the brain depend on the weak eye, it spends more time learning how to use it and develops better vision in that eye.
Kids often dread wearing it, and parents can have trouble forcing their children to keep wearing it, but it has improved the vision of millions of patients with lazy eye for the last thousand years.
There are pros and cons to each type of eye patch. No matter which type you choose, keep in mind that they will all get worn out and need regular replacement.
This is the standard most people think of when they hear the words, "eye patch". Often completely black to help block light, they sometimes come in a variety of shapes and patterns. Not the most comfortable, and not the cheapest, but are chosen because they are a good middle ground.
Disposable eye patches are like big band-aids: they have a paper backing that peels off so you can apply them to the eye. They often have trouble sticking on active young children for long periods of time and the cost can add up. They can be more comfortable and convenient compared to cloth patches.
Silk eye patches are just like cloth eye patches but are more comfortable but cost more.
After prescribing a new pair of glasses, eye patching is the next logical step in treating amblyopia. Although the costs are not trivial, it is one of the most affordable treatment options. Patching is the first line of defense against lazy eye and should almost always be tried first.
The eye patch was investigated by PEDIG, the NIH-funded pediatric investigator group that studies binocular vision problems and their treatments and is an evidence-based treatment for amblyopia with more studies supporting efficacy than any other treatment.
The PEDIG trials were a set of US government-funded clinical trials aimed to understand the pros and cons of the most common binocular vision treatments. Here's a summary of their findings:
The Pediatric Eye Disease Investigator Group (PEDIG) has conducted several randomized amblyopia treatment trials over the past several years. Results have shown that spectacles alone are a powerful treatment for amblyopia; patching is superior to spectacles alone; initiating fewer hours of prescribed patching seems to be as effective as traditional treatment; patching is effective in older children, particularly if they have not previously been treated; atropine is as effective as patching after six months; and weekend atropine is equally effective as daily atropine. Amblyopia Treatment: Results of PEDIG Studies, David K. Wallace">
The patch can be more affordable than alternatives which require more doctor visits. Many parents end up spending hundreds of dollars on a variety of different kinds of patches, so they aren't always as cheap as they might seem in the long run. It is typical to spend $50-$100 per month on eye patches and exercises.
Patching is a good first line of defense, but it does have many problems which cause it to be ineffective for some people.
Patching is the most well-studied treatment for amblyopia, and it does work. But it doesn't work for every child. PEDIG found that resolution of amblyopia, defined as visual acuity for the amblyopic eye within 1 line of the good eye occurred in only 25–33% of cases. Amblyopia Treatment: Results of PEDIG Studies, David K. Wallace">
PEDIG recommends that eye patching be used in patients younger than 13. This is because the young brain is still learning how to see, and is easier to change than the adult brain. Once a patient reaches 10-13, the ability to improve vision with eye patching diminishes, takes longer, and gets harder.
The results showed that treatment with patching and atropine was superior to optical treatment alone in children age 7–12 years. However, there was no significant difference in those children 13–17 years old. There was a significant age effect, as younger children showed a greater effect of augmented treatment (eye patching and atropine) relative to control than the older children.
In many cases, the eye can regress in the teenage years after a successful childhood treatment. Approximately 25% experienced a recurrence during the first year off treatment. Amblyopia Treatment: Results of PEDIG Studies, David K. Wallace">
Patch treatment takes time. Many doctors will recommend between two to eight hours per day, often for months or years. PEDIG says that most people stop after four to six months but improvements can continue after that amount of time.
The magnitude of VA improvement found at the mostly 4- to 6-month primary outcome examinations is not the maximum benefit expected to be achieved for all participants, but instead the maximum length of time that the prescribed treatment regimens could be maintained before investigators would insist on a change of treatment in cases of poor outcome; in many cases, VA can improve further with continued treatment. Amblyopia Treatment: Results of PEDIG Studies, David K. Wallace">
Asking a child to wear an eye patch and go to school can seem like one step short of blindfolding them and asking them to read their book or watch the board. Although an environment where they need to use their sight is a good one for improving it via patching, it also makes actually doing their work much more difficult.
The patch itself can be physically uncomfortable as well, making it even more difficult to keep on during the long periods that are required.
There are several alternatives and adjunct therapies to wearing the eye patch. Vision therapy exercises are often done alongside the patch. Virtual reality treatments are also often used as a companion treatment to the patch. Atropine eye drops are a kind of chemical patching that blurs the vision of the good eye.