Posts Under: Amblyopia

What is Amblyopia?

Ambly-what? Let’s sound it out… am-bly(blee)-o-pia… amblyopia. Great! Now we can all say it fast 5 times, but what does it mean? You may be more familiar with the term “lazy eye” even though neither one of the eyes are actually lazy. Amblyopia is a condition affecting 2-3% of the population, where one eye has reduced visual acuity (i.e. can’t see 20/20 even with correction) because the brain ignores or suppresses information from the eye. The two most common causes of amblyopia are refractive amblyopia, large differences in the refractive error between the two eyes, and strabismic amblyopia, a condition where the eyes do not align with each other.

Refractive Amblyopia

Refractive amblyopia develops when the difference in prescription between the two eyes makes it difficult for the brain to merge the two images together. If the brain is faced with one blurry picture and one clear picture, it will give preference to the clear picture and ignore information from the blurry one. The amblyopic eye isn’t actually lazy, it is just being overpowered, or bullied, by the better seeing eye. Over time the suppression of information from the amblyopic eye leads to reduced visual acuity.

Blurred Image (Amblyopic Eye) Normal Image (Non-amblyopic Eye)

Strabismic Amblyopia

The second most common cause of amblyopia is strabismic amblyopia. Strabismus is a misalignment of the eyes. When the eye muscles have trouble coordinating with each other and are not pointing in the same place at the same time, double vision can occur. As we discovered above, the brain gets confused when it cannot merge the two images together. Rather than seeing double, the brain will ignore information from the turned eye, which can lead to decreased visual acuity.

Is there an age limit for treating amblyopia?

It was once thought that if amblyopia was not treated before a certain, usually age 7, that nothing could be done. These assumptions were based on the belief that the brain did not retain neuroplasticity (or the ability to make new connections) after this “critical” period of development. Interestingly enough, the “critical period theory” was based on research done on cats in the 1960s and 1970s under very artificial conditions. While early intervention and treatment is always best, the National Institute of Health now recommends age not be the determining factor when deciding to treat amblyopia. Click this link to learn more: (National Institute of Health Study).

In her book, Fixing My Gaze, Dr. Sue Barry, a neuroscientist, explains how vision therapy can help patients with strabismus well into adulthood. She draws from her own experiences as a patient; as well as her neuroscience background. Optometric Vision Therapy places an emphasis on binocular (two-eyed) vision, rather than relying on traditional patching only methods. Patients of all ages can see improvements in both visual acuity and more importantly, depth perception, using this method.

How is amblyopia treated?

In the not so distant past, treatment for amblyopia was limited to patching of the better seeing eye. For patients who are not compliant with patching, a newer method of treatment uses eye drops to blur the better seeing eye. Neither of these options are very practical for school aged and older patients, whose daily functions include high visual demands. Recent studies have shown a different approach which uses Visual Perceptual Learning can be very effective in treating amblyopia well into adulthood.

Remember, successful treatment of amblyopia is ultimately about being able to use both eyes together as a “team”. Quality depth perception only occurs when the brain is able to fuse two images into one three-dimensional image. At our office, we combine Optometric Vision Therapy techniques, along with new advanced Visual Perceptual Learning techniques, to successfully treat patients of all ages.

We are particularly excited about our new virtual-reality based vision therapy program. In this program, we are using the latest virtual-reality technology combined with a video game that is specifically designed for patients with amblyopia and strabismus. This system is both fun and functional. For many patients, this program has allowed them to experience three-dimensional (3-D) depth perception for the very first time! While this program is not a stand-alone treatment for amblyopia and strabismus, it has become an important tool in our office. You can find out more about Vivid Vision here.

As research and our understanding of amblyopia is rapidly changing, not all doctors are aware of or are utilizing these new techniques and technology. It is important to find a doctor who specializes in Optometric Vision Therapy and Visual Perceptual Learning techniques.

Dr. Valerie Frazer practices Developmental Optometry and specializes in Optometric Vision Therapy near Madison and Milwaukee, WI. Contact us at 608-849-4040 or info@newhorizonsvision.com with your questions.

Amblyopia is a condition often called “lazy eye” where one eye has reduced visual acuity (i.e. can’t see 20/20), even with the appropriate glasses. Amblyopia occurs when the brain ignores or suppresses information from one eye. This condition affects 2 to 3 out of every 100 children; making it one of the most common causes of reduced vision in children. Below I will discuss 3 common myths about treating amblyopia.

Before we get into the common misconceptions about treatment for amblyopia, let’s first discuss how amblyopia develops. The two most common types of amblyopia are Refractive Ambylopia and Strabismic Amblyopia.

Refractive Amblyopia

Refractive Amblyopia is the most common type of Amblyopia. This occurs when there is a large difference in refractive error (a.k.a. the prescription needed to focus an image on the retina) between the two eyes. Refractive Amblyopia develops because the images in each eye are different or when one eye must work harder than the other to see. These differences between the picture created by the two eyes makes it difficult to merge the two images together into one.

Blurred Image (Amblyopic Eye) Normal Image (Non-amblyopic Eye)

If the brain is faced with one blurry picture and one, clear picture it will give preference to the clear picture and ignore information from the blurry one. Over time this suppression of information leads to reduced acuity. Usually the amblyopic eye will also have greater difficulty with other visual skills such as focusing, tracking, eye-hand coordination and higher levels of visual processing because of this. In cases of Refractive Amblyopia, wearing the appropriate prescription is an important aspect of treatment.

Strabismic Amblyopia

The second most common cause of amblyopia is strabismus. Strabismus is a misalignment of the eyes, usually esotropia (eye turn in) or exotropia (eye turn out). When the eyes have trouble coordinating with each other and are not pointing in the same place at the same time, the brain gets confused and cannot put the images together. Rather than seeing double, the brain will ignore information from one of the eyes. Usually it ignores information from the eye that is turned most often; eliminating the double vision.

Amblyopia affects one in every 40 children

Strabismic Eye

Now, let’s review the most common misconceptions about amblyopia treatments…

Myth #1= The most effective method of treating amblyopia is patching.

Many eye doctors use patching as their primary method of treating amblyopia. If you are the parent of an amblyopic child, you need to know that there are better ways to treat amblyopia then long hours of patching. In fact, a recent study from the National Eye Institute (https://nei.nih.gov/news/pressreleases/051203) shows that two hours of patching is as effective as all day patching. A patch can be one effective tool when used properly; however, it is not the only tool. In my practice, patching is often done with other prescribed activities to equalize visual skills between the two eyes. A patch is usually worn while doing prescribed activities for lesser periods of time.

A newer approach to treating Refractive Amblyopia doesn’t involve a patch at all. One of the problems that occurs in Refractive Amblyopia is that because the prescription is different between the two eyes, the image sizes are also different. Even with the correct prescription, the brain has a hard time putting two different sized images together, and the eyes can still struggle to work together. The Shaw Lens is designed to reduce the image size differences that occur when one eye needs a stronger prescription than the other. We are proud to be one of the first clinics in the area to provide this new technology to our patients. Although more research needs to be done, our clinic is seeing improved visual acuity after one month of wearing the Shaw lenses. More information about the Shaw lens can be found on their website: http://shawlens.com/aniseikonia/amblyopia/ .

Myth #2= Amblyopia can’t be treated after a certain age.

In the past, many in the medical community believed that amblyopia could not be treated after age eight. These assumptions were based on the false belief that the brain did not retain neuroplasticity (or the ability to make new connections) after this “critical” period of development. While early interventions and treatments are always the best, new studies by the National Institute of Health (https://nei.nih.gov/news/pressreleases/041105 ) recommend that age should not be a determining factor when deciding to treat amblyopia. Future studies are looking at the effectiveness of treating adults with amblyopia. Many offices who specialize in vision therapy, including ours, successfully treat amblyopia well into adulthood. These adult patients are making improvements in both visual acuity and depth perception. It is never too late to treat a “lazy eye”.

Myth # 3= Once 20/20 vision is achieved, the amblyopic eye is “cured”.

This is a common mistake even well trained eye doctors will make. Remember that amblyopia is not exactly an “eye” problem, it is a brain problem caused when images from the two eyes cannot be merged effectively and efficiently. Even if the eye with amblyopia can see 20/20, it doesn’t mean that the amblyopic eye transmits or processes visual information as efficiently as the non-amblyopic eye, or that the brain can sync the information together. The brain could still be ignoring/suppressing information from the amblyopic eye when both eyes are open.

Depth perception at distance and near should be the goal of any amblyopia treatment plan. Quality depth perception occurs when the two eyes are working well together and the brain is then able to combine the information into one 3-D image. Patching alone is often not enough to teach the eyes how to work together. Vision therapy is often required to achieve quality depth perception and to ensure that the eyes will want to stay working together long term.

Please contact our office with any questions you may have at info@newhorizonsvisiontherapy.com . Or to schedule an evaluation call us at 608-849-4040.

Dr. Valerie Frazer, FCOVD