Download Strabismus/Amblyopia - Carolina Center for Eye Care

Amblyopia/Strabismus
Allison D. Lyerly, OD
Dr. Allison Lyerly is an optometrist with Carolina Center for Eye Care. She has a passion for children and
a wealth of experience with learning related visual problems, amblyopia, and strabismus. If your child is
experiencing difficulty in the classroom, with sports, or if you have questions on how binocular vision
training would benefit your child, please feel free to contact Dr. Lyerly.
Advance: (336) 940-2015
Lewisville: (336) 946-0203
Amblyopia, also referred to as “lazy eye”, is an eye condition resulting in reduced vision. There are many
causes of amblyopia. The most common are:

Strabismic Amblyopia: This type of amblyopia results when an “eye turn” is present. If the two
eyes do not aim at the same place, the brain will suppress (block, ignore) the turned eye so as
to avoid confusion and/or double vision. When the brain ignores the turned eye, adequate
vision from that eye will not develop on its own.

Refractive Amblyopia: This condition occurs when one eye sees clearly and the other eye needs
a rather large glasses prescription in order to see clearly. The brain will ignore the blurrier eye
and adequate vision will not develop on its own. This is one of the hardest types of amblyopia
to detect because many times the child will not notice the blurry eye.
o
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In some children, if the refractive amblyopia is large enough, an eye turn may actually
develop as well.
In other children, both eyes may have a larger glasses prescription and amblyopia can
develop in each eye. The brain will choose to use the eye with the lower prescription
because it will see a bit clearer than the other eye.
According to researchers at New York University's Center for Neural Science, amblyopia is the most
common neurological defect of vision in children and adults and affects 1-3 percent of the population.
Many are unaware that amblyopia is a neurological deficit, not a problem with how the eye itself works.
Can surgery help to correct a “lazy eye”?
No surgery can correct the vision in an amblyopic eye. For children who have an eye turn, a cosmetic
surgery may be performed to help reduce the angle of the eye turn; however, this only realigns the eye
muscles and does NOT solely improve vision. Before a “muscle surgery” is ever performed treatment
options directed specifically toward vision improvement should be exhausted before surgery is
considered.
Binocular Vision Training (BVT)
Q: What is BVT?
A: Binocular vision training (BVT) is an individualized treatment program designed to improve visual
skills that cannot be effectively treated with glasses, contact lenses, or surgery alone. At Insight, patients
work one-on-one with our doctor and therapists to achieve the vision necessary to navigate everyday
challenges.
Q: How would BVT help strabismus or amblyopia?
A: Binocular vision training is based on the concepts of neuroplasticity. Since amblyopia is a deficit in the
neurological system, treatment is aimed at strengthening the visual channel that is being suppressed.
Many doctors will passively “patch the good eye” to get better vision out of the “weaker eye”. Patching
therapy, alone, does not produce the best visual outcomes. Even if better vision is achieved out of the
“weaker eye”, the brain does not know how to properly use both eyes together. Often, this results in the
brain suppressing the “weaker eye” again. Suppression leads to poor depth perception, stereo blindness
and other associated symptoms. BVT works toward the goal of excellent vision WITH excellent eye
teaming abilities.
Q: How do I know if my child would benefit from BVT?
A: When visiting your optometrist, it is important to tell them how your child is performing at school and
in sports. A comprehensive eye examination looks at many aspects of your child's visual health, but
certain testing is only completed if an eye teaming problem is suspected. A second, more in depth
evaluation of your child's visual system is often required to determine the type of eye teaming difficulty
that may be present. Great vision is so much more than "20/20". Please alert your optometrist to any
reading or school related difficulties your child may have. Every child deserves to have the best visual
foundation for a lifetime of learning.
Q: What is depth perception and why is it important?
A: Depth perception is the ability to judge distance between objects or see the world as three
dimensional. Depth perception requires an individual to point both eyes at the same target with CLEAR
vision. Then, the brain must fuse the two images received by each eye in order to perceive depth. Those
with amblyopia often lack depth perception and must employ other cues to judge distances, making
their depth perception less accurate. Without accurate depth perception children can experience
difficulties in learning, reading, driving, and sports. Many careers require certain levels of depth
perception as well (pilot, surgeon, sports, etc).
Q: My previous doctor said that my child would not benefit from BVT or patching because they have
passed the “critical age period”.
A: Many doctors believe that there is a “critical age” past which the brain’s neuroplasticity cannot be
shaped to result in better vision and depth perception. Although it is easier to treat amblyopia at an
earlier age, age is NOT a barrier. See the below article on Sue Barry, a neuroscientist who started vision
therapy to treat her amblyopia during her 40’s!
Q: What does ophthalmology think about binocular vision treatment?
A: Opthalmologists agree, current patching treatments are effective in improving acuity. However, many
children are left with residual vision deficits, ocular motor abnormalities, deficient fine motor skills and a
risk for recurrent amblyopia. The Pediatric Eye Disease Investigator Group (PEDIG) is currently working
on a controlled, randomized trial to demonstrate the benefits of binocular therapy in treating
amblyopia/strabismus.
Helpful Therapy Links
Below is a list of websites that are helpful in researching BVT and amblyopia/strabismus.

College of Optometrists in Vision Development
o http://www.covd.org/

What is Vision Therapy?
o http://www.visiontherapy.org/

Vision Help
o http://www.visionhelp.com/

New Approaches to Amblyopic Treatment
o https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3577063/

The Wow Vision Therapy Blog
o http://wowvision.typepad.com/

Jillian's Story
o http://www.jilliansstory.com/

Susan R. Barry-author of Fixing My Gaze
Fixing My Gaze is an inspirational book by neuroscientist, Susan Barry, who was born with
strabismus (an eye turn) and had lived all her life without stereo vision, meaning that she could
not see in three dimensions. Her case was also the subject of an article by Oliver Sacks titled
"Stereo Sue" published in the New Yorker.
She had three surgeries to "correct" the eye turn cosmetically but she still could not see properly
and the eye was still turned, although less than before. She had lived this way for over 40 years
until she met optometrist Dr. Theresa Ruggiero.
Dr. Ruggiero treated Susan with vision therapy which corrected the eye turn and allowed her see
in three dimensions for the first time in her life. Can you imagine how her world was
transformed?
Here is what Susan Barry said in an interview with Scientific American about how the world
looked different after vision therapy:
"For the first time, I could see the volumes of space between different tree branches, and I liked
immersing myself in those inviting pockets of space. As I walk about, leaves, pine needles, and
flowers, - even light fixtures and ceiling pipes - seem to float on a medium more substantial than
air. Snow no longer appears to fall in one plane slightly in front of me. Now, the snowflakes
envelope me, floating by in layers and layers of depth. It's been seven years since I gained stereo
vision, but ordinary views like these still fill me with a deep sense of wonder and joy."
Susan Barry's story is remarkable in that she was in mid-life when she received vision therapy.
The conventional wisdom, now being disproved by new studies, was that after a "critical period"
around the age of 7 or 8, the brain could not be trained (or "rewired") to see in new ways. The
old scientific thinking was that after early childhood, the brain became fixed. In fact, Susan
Barry herself and other scientists thought that it was impossible for her to ever see in 3D.
Now, we know that the brain exhibits neuroplasticity and that given the proper behavioral
therapy, even adults can rewire their brains. This has given hope to many people who did not
receive treatment for visual processing disorders at a young age. Now it seems possible that even
older patients with amblyopia or strabismus and other binocular vision disorders can benefit
from treatments like vision therapy.
You can hear interviews with Susan Barry and read more about her story at her
website: http://www.fixingmygaze.com/.