Why effective Amblyopia treatment requires binocular vision rehabilitation

Recognized as a significant vision problem that affects millions of people worldwide, one of the “hot topics” of  advocacy at the recent 2019 VisionHelp Annual Meeting  was Amblyopia. 

Amblyopia/Lazy eye is a serious neurodevelopmental vision problem that causes vision loss in approximately 2-4% of the population or 1 in 30 people. Neuroscience has shown that Amblyopia occurs when there is a unilateral failure in binocular vision, occurring early in life typically infancy or toddlerhood.

When the binocular system is broken at a young age, a neuroadaptation occurs, known as suppression where the signal from one eye is “shut down” by the brain to counteract the confusion created by the broken binocular system. As a result of this unilateral failure of binocular function a cascade of delayed visual function occurs leading to the following:

  1. Reduced visual acuity (eye sight) in one eye
  2. Reduced, or no stereo acuity (depth perception)
  3. Poor saccadic eye movement 
  4. Poor visual processing ability
  5. Poor eye hand coordination

Thus, due to a failure in binocular vision, a spiral of visual problems occurs that is much more involved than visual acuity of one eye. But, because visual acuity is reduced in one eye even with best correction, Amblyopia is one condition in optometry and ophthalmology that should never be misdiagnosed or overlooked.

The issue presented at VisionHelp 2019 was, in spite of the obvious hard to miss diagnosis of Amblyopia, as well as the impact of a failed binocular visual system on a patient’s life that supersedes the visual acuity loss in one eye, there is a need to improve professional and public understanding for effective Amblyopia management.

Indeed, even though patching for Amblyopia has been around for 300 years, it still is touted on many notable sources to be the treatment of choice for amblyopia. In fact, patching the non-amblyopic eye, either part-time or full-time, is evidence-based and outlined in various PEDIG Amblyopia Treatment Study (ATS) research clinical trials. These ATS clinical trials have shown a moderate amount of improvements in the visual acuity function of the amblyopic eye with occlusion therapy. However, what the PEDIG ATS research doesn’t show is that patching has a multitude of negative side-effects that are outlined in several other research papers. In addition visual acuity gains often regress when the treatment ends, plus and even more important, patching does not repair the broken binocular visual system which is the underlying cause for patient’s amblyopia.

It should seem fairly obvious that you can not repair a broken binocular system by patching an eye. Patching only re-enforces the failure of binocular vision. Therefore, 3-D, depth perception, ie stereo acuity, which is a measure of the quality of binocular vision, is ignored when a patient is sent home to wear an eye patch.

Therefore, using an occlusion-based model of treatment, stereo acuity does not develop nor do the related other conditions involving poor micro eye movement, poor visual processing and poor eye hand coordination.

Additionally, while there have been recent studies that have tried to explore binocular vision treatment for amblyopia, (PEDIG ATS-18) due the treatment design centered around a home-based model with once a month office monitoring (for 16 weeks), compliance by the patient was very poor resulting in less than optimal outcomes. Even though previous clinical trials exploring the best modality of delivery of care has proven that home-based models are no more effective than a placebo, the investigators of the recent PEDIG ATS-18 study presumably made the assumption that  a home-based model of treatment, with once every 4 weeks office monitoring, would somehow substitute for the professional guidance of an office-based model and get better compliance presumably because the binocular activity was an iPad game.

So, it was no surprise that with only once a month visits to the clinic over 16 weeks,  the compliance results for the two age categories being studied with the binocular video game were substantially below the required time to get results. For the two groups studied, age 5-12 year old, the compliance was 22% and for the 13-18 year old the compliance dropped to 13%.

Yet, instead of showing that the research subjects did not follow the prescribed dosing time, based on guidelines set by previous cohort studies, they simply concluded that binocular vision therapy was not effective. 

In conclusion, it’s important for professionals and patients to understand that the loss of monocular best corrected eyesight in Amblyopia is due to a broken binocular system. Due to this failure in binocular vision, effective treatment must include the vision rehabilitation of visual processing, oculomotor/saccadic eye movement, eye-hand coordination that begins with vision rehabilitation of the binocular visual system. The progress in vision rehabilitation should be measured not just based on visual acuity, but also stereo acuity and specific tests of visual processing and eye-hand coordination. Furthermore, research shows that effective developmental vision rehabilitation must be office-based with home support that is closely monitored and altered as needed to get consistent compliance and results. 

The VisionHelp Guidelines show that for treatment to be most effective, the following is recommended:

  1. To establish the diagnosis and various elements of treatment, the patient must have a comprehensive developmental vision evaluation including eye health, refraction, establishing optimal lenses for best corrected visual acuity,  binocular vision assessment, including measure of stereo acuity, oculomotor assessment, visual perceptual evaluation, and visual motor integration evaluation.
  2. Prescribed treatment should be 45-60 minutes office-based vision therapy, 1-2 times per week, with 1 hour per day of home activities that require close support by the supervising doctor and/or vision therapist.
  3. Home activities must have sufficient novelty and high level binocular stimulation including stereo acuity development. (examples: virtual reality in vision therapy
  4. Weekly progress on visual acuity, sensory fusion, suppression zone, stereo acuity. When these areas are not making expected progress the treatment activities and compliance must be carefully analysed with proper adjustments made to bring about improvements. 

Only when the complexity of Amblyopia is addressed with a comprehensive developmental vision rehabilitation delivery of care model, will patients have the chance to have successful outcomes in their amblyopia treatment. We must begin to realize that the best care for patients with amblyopia goes beyond patching.

For more information, the VisionHelp Amblyopia Project provides treatment protocols for most effective results.

Dan L. Fortenbacher, O.D.,FCOVD

Stereo Acuity as the Dow Jones Index of Binocular Function in Amblyopia

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In the current issue of Vision Development & Rehabilitation, Bob Sanet, Pilar Vergara and I have a Perspective piece in which we review a Paradigm Shift in the Treatment of Amblyopia.  The article resurrects a formula proposed by Dr. Arnold Sherman to provide a more accurate measure of the extent of treatment success in amblyopia, now that current research has squarely positioned the condition as a binocular problem in which visual acuity is simply one monocular sign.  Sherman notes that Mayer and colleagues proposed an Amblyopia Success Index (ASI) based on visual acuity as follows:

ASI = (Initial VA – Final VA) / (Initial VA – Test Distance) x 100. As an example, if the initial acuity was 20/60 and improved to 20/30, the ASI = (60- 30/60-20) = (30/40) x 100 = 75%.

Given the significance of amblyopia as a binocular problem, Sherman proposed an analogous Binocular Success Index (BSI) using Wirt Circle Stereopsis (WS) in seconds of arc as a guide. A maximum value in most commercially available tests of 20 seconds of arc is the constant. His formula is: BSI = (Initial WS – Final WS) / (Initial WS – Maximum WS) / x 100.

As an example, if initial stereo acuity was 100 seconds of arc and improved to 30 seconds of arc, the BSI = (100-30) / (100-20) = (70/80) x 100 = 88%. He suggested that the more appropriate index of success in amblyopia would be the average of the ASI and BSI, in this instance (75 + 88) / 2 x 100 = 82%.

While the numbers in Sherman’s example don’t seem significant when differentiating between a 75% level of success and an 82% level of success, combining ASI and BSI obviously becomes more significant when stereopsis improves to a considerably greater extent that visual acuity. For example, using the formula for ASI, a patient who improves from 20/50 to 20/40 would be assigned a success index of only 33%. But if that patient improved from 100 seconds of arc to 20 seconds of arc, BSI is 100% which doubles the overall success index to 67%.

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For many years we have routinely conducted the Wirt Circle test on all of our patients (with or without amblyopia).  In all of our patient reports I have included this phrase: “Stereopsis is a sensitive index of binocular function.  On the Wirt Circle Test, ________ scored at the level of X% accuracy.”   In other words, if 5 out of 10 are correct, the patient is assigned a score of a 50% level of accuracy.  While I realize this isn’t as sophisticated or technically as accurate as Dr. Sherman’s index, it is a justifiable simplification of the test result.  That way, when we re-test with a suitable lens/prism Rx, or after vision therapy, we can say that the patient improved from X% level of accuracy to Y% level of accuracy.

Nearly 30 years ago, in an article in the Journal of Behavioral Optometry, Dr. Selwyn Super pointed out some of the nuances of stereopsis testing.  He made the observation that speed of the stereopsis response may prove to be just as valuable as the stereo acuity measure in seconds of arc.  When taking visual acuity measures, the patient with amblyopia takes longer to respond, particularly as we approach the limit of their visual resolution, so this lag in the speed of stereo acuity responses is not entirely surprising.  Although he introduced a test for the speed of stereopsis based on Wirt Circle responses that was distributed by OEPF, it was ahead of its time and removed from the market. There is reference to this test in a master’s thesis on file with Pacific U. College of Optometry.  It remains a valuable concept, and would be another potentially useful metric in differentiating amblyopia and documenting response to treatment.

ODs on FB Logo

I just did a quick survey of ODs on Facebook, a community of primary care optometrists, posing this question:  Does your office routinely test stereopsis on all pediatric patients? Please indicate “yes” or “no”.  Realizing that this isn’t a scientific survey since it wasn’t “anonymous”, and the people who don’t do the test tend not to answer in a forum of that nature, it was still encouraging to note that among the first 200 respondents there were 197 yes and 3 no.  Although I didn’t ask respondents to indicate how many considered themselves primary care optometrists, it would be reasonable to expect that the high majority are.  A public word of thanks to all those who responded.

If our premise regarding amblyopia is correct, that stereo acuity is a sensitive index of binocular function, most primary care optometrists have a tool at their disposal that they’re already using that will help facilitate the paradigm shift in amblyopia from a monocular emphasis to a binocular balance.

Dichoptic Treatment of Amblyopia in a Clinical Setting

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This is a relatively brief post to bring to your attention a continuing education article now available online through Clinical & Refractive Optometry titled Dichoptic Treatment of Amblyopia in a Clinical Setting – a Retrospective Study, authored by Giovanni M. Travi, MD, Seyedbehrad Dehnad, and Behzad Mansouri, MD, PhD, FRCSC.  Dr. Travi is an ophthalmologist and biomedical engineer; Dr. Mansouri is a neuro-ophthalmologist; and Seyedbehrad Dehnad is their research assistant at the University of Manitoba in Winnipeg, Canada.  If Dr. Mansouri’s name seems familiar, it is likely because he is a co-author of the paper in Restorative Neurology and Neuroscience, along with Hess and Thompson at McGill University in Canada in 2010, that introduced dichoptic training of amblyopia into the literature.

I like the authors’ description of amblyopia, contained in the introduction to this paper:

Amblyopia is an abnormal development of the visual system secondary to its inadequate (i.e. anisometropia and deprivation amblyopia) or erroneous (i.e. strabismic amblyopia) binocular stimulation during early visual development. It is usually unilateral, and it occurs due to a mismatch of information between the two eyes. Beyond affecting the visual acuity, amblyopia affects contrast sensitivity, spatial integration, global motion perception, and depth perception.  Moreover, it may impact negatively the quality of life, either due to the low vision in the amblyopic eye, weak depth perception or because of the social burden of the most widely used treatment, i.e. occlusion therapy.  Recently, the understanding of unilateral amblyopia physiopathology has evolved and the concept that the visual loss is related uniquely to an abnormally developed visual system has given place to the one based on an anomalous binocular interaction.


Here is the authors’ abstract:

Purpose: Dichoptic visual stimulation has been evolving as a promising treatment for amblyopia. We aimed to assess the visual outcomes of Dichoptic Amblyopia Treatment (DAT) in a clinical setting for patients who had completed all conventional amblyopia treatments and did not have any other clinical treatment options. The primary outcome was the improvement of visual acuity (VA) in children and adults. The secondary outcomes were improvement in stereo acuity (SA) and reduction of suppression.

Methods: We performed a retrospective chart review of amblyopic patients who received DAT from 2014 to 2016 in an eye care practice. DAT consisted of playing “Falling Cubes” game on an iPod, using dichoptic presentation.

Results: 23 patients with a median age of 12 years-old (Interquartile range (IQR) = 9-30) met the inclusion criteria. 3 patients were excluded on the final VA analysis due to non-completion of treatment. The median for pre- and post- treatment VA was 0.54 (IQR=0.41-0.84) and 0.19 (IQR=0.09- 0.28) logMAR, respectively. Mean improvement in VA was 0.33 ± 0.18 logMAR (IQR=0.25-0.41) (p<0.001). Patients showed an improvement in SA (p=0.002) and a decrease in suppression (p=0.003). Age group, presence of SA at baseline, previous treatment, amblyopia type and severity did not correlate with VA improvement. There was no adverse effect such as double vision or VA reduction in the sound eye.

Conclusion: To the best of our knowledge we showed for the first time that DAT is a plausible amblyopia treatment at a clinical environment. The results demonstrate that DAT is effective in improving VA and SA, and reducing suppression in amblyopia. We emphasize the importance of an active follow-up regarding game monitoring and frequent patient’s reassessments.

The “Good Eye” in Amblyopia Isn’t as Good as You Think It Is!

Chances  are by now you’ve heard about the new paradigm in amblyopia treatment emphasizing a binocular approach to therapy, as reviewed extensively in The Amblyopia Project.

IOVS Cover August

A new article in the August issue of Investigative Ophthalmology & Vision Science adds to that body of evidence, and reinforces that vision in the fellow eye is negatively impacted by amblyopia.  The amblyopic or “lazy” eye tends to get all of the attention because visual acuity through that eye is clearly not as sharp as through the other eye.  In fact, that’s how most people still conceive of amblyopia despite all the evidence showing that reduced visual acuity is only the tip of the iceberg.

The new article we’re talking about in IOVS is titled Impaired Fellow Eye Motion Perception and Abnormal Binocular Function.  It notes that binocular discordance due to strabismus, anisometropia, or both may result in not only monocular visual acuity deficits, but also in motion perception deficits.  The specific deficit studied here is called  motion-defined form perception, or MDF  – the ability to identify a two-dimensional shape defined by motion rather than luminance contrast.


The idea here involves a coherent motion display, in which the subject has to judge the direction of moving dots or squares, a fixed proportion of which are moving in a specified or coherent direction.  The display in the IOVS paper includes the following figure and explanation.

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Top: MDF stimulus showing a horizontal rectangle defined by 100% coherently moving dots moving upward inside of a central horizontal rectangular area and 100% coherently moving dots moving downward outside of the rectangular area (i.e., a long spaceship). Bottom: The stimulus appearance when motion coherence is reduced to 75%; 25% of the dots are moving in random directions both inside and outside the rectangular area. Yellow dotted lines are not present on the display during testing; they have been added to the figure only to highlight the rectangular borders of motion contrast.

The bottom line of the study is that fellow eye MDF deficits were common in 7- to 12-year-old children with residual amblyopia, occurring in 23% of the cases, and to a similar extent through the amblyopic eye when treatment was limited to patching.  When stereoacuity was present, the percentage of children with MDF deficits in the amblyopia and fellow eye went down considerably, between 4 and 7%.  When stereoacuity was absent, the presence of MDF deficits rose dramatically, to 36%.  This is not surprising when we conceive of amblyopia as a binocular vision deficit.

The article concludes as follows:  “Fellow eye MDF deficits were significantly more common among those treated with patching than among those who had binocular amblyopia treatment. We were also able to observe that binocular amblyopia treatment was associated with a reduction in mean fellow eye MDF threshold and a higher proportion of children with fellow eye MDF thresholds within the normal range. These data support the effectiveness of binocular amblyopia treatment, designed to decrease or eliminate suppression and provide binocular visual experience in rehabilitating fellow eye deficits.”



Revisiting Telescopic Acuity in Amblyopia

Hard to believe that it’s thirty six years (yikes!) since I authored an article for the journal of the American Optometric Association titled Telescopic Acuity in Amblyopia.  The impetus for that article originated from interactions with the Feinbloom Center of The Eye Institute a few years earlier.  Dr. William Feinbloom was convinced that patients with organic amblyopia due to disease had a functional overlay, particularly when the disease entity was quiescent.  This resulted not only in compensatory magnification enabling better acuity through his spectacle mounted telescope, but a gradual improvement in visual acuity without the telescope in place providing a therapeutic benefit.  With master’s and Ph.D. degrees in biophysics and visual psychology from Columbia University, I took whatever Feinbloom said seriously.


It has long been recognized that a diagnostic sign of functional amblyopia is an improvement in visual acuity beyond the magnification power of the telescope.  In other words, a patient with 20/100 acuity would be expected to obtain 20/40 acuity when focusing through a 2.5x telescope.  Improvement beyond 20/40 not only indicates functional amblyopia, but is a reasonably good indicator of what to expect as an endpoint acuity after therapy.  In analyzing why the use of a telescope should have a functional and therapeutic effect, Feinbloom suggested that magnification accentuated central vision, and placed a premium on the stabilization of eye movements in order to localize and study the visual scene.

Bernell still distributes the Selsi hand-held monocular telescope that would be ideal for therapy activities.  Beyond the original 2.5x model, powers are also available in 4x, 6x, 8x, 10x, and 15x.  The higher the degree of magnification, the greater the need for steady fixation or the negative consequences of unsteady fixation when localizing points of regard.

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Although I gravitated away from using the hand-held monocular telescope for therapy, it may be an opportune time to resurrect its use in amblyopia for two compelling reasons:

1) Research has shown that patients with amblyopia have deficits in perception of images in real world scenes.  Active exploration with the telescope is not only fun, but is well suited for real world scenes or natural viewing.

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2) Rather than occluding one eye, focusing with the telescope through the amblyopic eye while the fellow eye is open is a form of MFBF that is more compatible with the newer trends in treatment that “ditch the patch” while both eyes are open.

The New Paradigm in Amblyopia Therapy

The utility of occlusion for binocular dysfunction is limited to patients for whom binocular vision is too confusing due to constant or variable diplopia. Oft times these patients will be responsive to vision therapy, lenses, prisms, syntonics or other therapeutic interventions but, in those rare instances when it is not, the tradeoff of losing half of one’s visual field in occlusion is worth the relief to the brain of trying to suspend or de-tune the troublesome second image.  In many instances diplopia can be sufficiently alleviated by spot or sector occlusion rather than total occlusion, thereby preserving peripheral vision in both eyes.

This does not apply to amblyopia, for which occlusion leads to con-fusion, as our colleague Dr. Dan Fortenbacher demonstrated in his presentation on advanced treatment of amblyopia six years ago.

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By con-fusion we mean that any time the patient is patched, we’re sending the brain a negative message counter to binocular vision.  That is illogical now that the consensus in vision science is that the source of amblyopia itself is a disruption to binocular vision and, as recently reviewed by Kraus and Culican, the depth of amblyopia is positively correlated to the degree of binocular imbalance.  Can you think of another form of therapy for which the mainstay of treatment is the source of the problem?  Neither can I, and that is the fundamental reason why the paradigm in amblyopia therapy has shifted from a focus on the amblyopic eye to emphasis on binocular integration.

In 2012 Dr. Daniel Press and I co-authored a paper that followed the methodology of Dr. Anrold Sherman who who reverse engineered hyperopic anisometropic refractive amblyopia.  Dr. Sherman originally termed the condition Adaptive Refractive Error Syndrome which he considered to be the origin of refractive amblyopia.  In a subsequent paper that provided his rationale for undercorrecting the eye with more ametropia, and treating the condition without occlusion, Dr. Sherman writes:  “If binocular interference is the major etiological factor in amblyopia development, treatment must be designed to eliminate it and achieve binocular cooperation.”

Scientific Reports Logo

As reviewed by Zhao et al in Scientific Reports, visual acuity is widely used in the diagnosis of amblyopia and has traditionally been the metric most valued by clinicians.  They demonstrate that although occlusion can aid in the recovery of some visual functions including visual acuity, stereo vision, and binocular rivalry at low spatial frequency, many other binocular visual functions remain deficient including binocular rivalry at high spatial frequencies, interocular summation, and interocular phase combination.  While their results support the observation that occlusion treatment is not sufficient to recover all the visual functions in amblyopia, and that additional treatment is necessary,  the new paradigm goes a step further in stating that for many forms of amblyopia, occlusion is actually counterproductive.  If occlusion has any remaining application, it may reside in rapid alternating occlusion and flicker therapy as published by Vera-Diaz and colleagues.

The final nail in the coffin of occlusion therapy may be emanating from research at the SUNY College of Optometry addressing the brightness deficit in amblyopia.

Journal of Neuroscience

Published this month in the Journal of Neuroscience, the SUNY research shows that amblyopia increases visual dark dominance by three to ten times, and that the increase in dark dominance is strongly correlated with the severity of amblyopia.  The implication of this research is that one of the keys to effective amblyopia therapy involves ameliorating the brightness deficit in amblyopia.  In that regard, occlusion is counterproductive because it reduces brightness.  One of the reasons that two eyes are better than one, even  on a task as basic as visual acuity (for example OU acuity vs. OD or OS on the Snellen Chart) is a boost in brightness perception due to binocular summation.

How do we boost brightness perception through the amblyopic eye?  Bear in mind that Claud Worth, over a hundred years ago, invented the Amblyoscope as a device that emphasized ways to improve vision through the amblyopic eye.  He didn’t call it a Strabismoscope or a Troposcope, which placed emphasis on the motor misalignment in strabismic amblyopia.  He was interested in rehabilitating the sensory deficits in amblyopia which, as it turns out, occur at the neural or cortical levels.  Clement Clarke did a better job than American Optical with terminology in that regard, changing the name of its device to Synoptophore, the “Syn” signaling togetherness of the eyes, parenthetically calling it the Major Amblyoscope.  The major advancement over Worth’s device was the ability to boost brightness to the amblyopic eye, and engage in what more recently has been termed the “push-pull” balance between the amblyopic and fellow eye.

On a final note, in bypassing occlusion we may be trading off a final outcome that in select cases would be better if occlusion were “judiciously applied”, much as one would judiciously apply lenses or prisms.  The patient with unilateral strabismic amblyopia typically has some degree of eccentric fixation.  Monocular activities such as Haidinger Brush done while the non-amblyopic eye is occluded are usually necessary to adequately stimulate foveal fixation that provides 20/20 rather than something a bit less.  But the patient or parent who is compromised by amblyopia and has improved considerably not only in visual acuity, but in many aspects of life really doesn’t care whether they end up with 20/20 unless we make that the sine qua non of a “cure”.  Much as the patient with strabismus really doesn’t know or care if she has anomalous or normal correspondence, the patient with amblyopia doesn’t know or care if she has eccentric or central fixation.  As a wise patient said to me many years ago: “You don’t have to make it perfect, doc.  You just have to make it better.”

Latest JAMA research shows impact of Amblyopia/Lazy Eye runs deeper into children’s lives

In the November 2018 issue of the Journal of the American Medical Association (JAMA) Ophthalmology, in a paper entitled: Self-perception of School-Aged Children With Amblyopia and Its Association With Reading Speed and Motor Skills, the researchers from the Foundation of the Southwest, Dallas, Texas Department of Ophthalmology, came to an interesting conclusion. In this cross-sectional study conducted at the Pediatric Vision Laboratory of the Retina Foundation of the Southwest, from January 2016- June 2017, involving 81 healthy children grades 3rd – 8th, 50 with Amblyopia and 31 without amblyopia, researchers learned that those children with Amblyopia have lower self-perception associated with slower reading speed affecting their scholastic competence and poorer motor skills which affects the child in their athletic competence, social competence and behavioral conduct.

This paper was particularly interesting to me because for nearly four decades I’ve had the privilege to provide care in this specialty of optometry known as developmental vision and rehabilitation, working to help children (and adults) to improve in their vision development. I have examined and treated hundreds of children with amblyopia (lazy eye) observing them initially struggle with a lower sense confidence in ball sports, general athletic ability, and for many, academically due to slower reading speed and fluency errors. While this observation of lower self perception, prior to treatment is a relatively common theme, after binocular vision therapy when the child gains depth perception, better eye-hand coordination, visual tracking and overall visual development, it has been particularly gratifying to see them blossom in reading abilities, sports performance and self confidence.  

Now, thanks to Dr. Eileen Birch and the team of investigators at the Pediatric Laboratory of the Retina Foundation of the Southwest,  we have this new research that validates these observations and more importantly shows, or strongly infers, that we must look at Amblyopia as more than just reduced visual acuity in the affected amblyopic eye. We must understand the overall impact that Amblyopia has on a child’s perception of themself and how treatment must target not only visual acuity but also binocular vision, depth perception, oculomotor and saccadic eye movement.

While every child with Amblyopia should have a comprehensive eye health and vision evaluation with proper lenses prescribed as needed, it’s important to emphasize, as written in previous VisionHelp Blog posts, patching or Atropine drops (occlusion therapy) alone will not address these issues identified by the researchers in this JAMA- Ophthalmology paper. Here are the conclusions by the researchers:


  • “The association between self-perception of scholastic competence and reading speed, along with our prior finding that decreased reading speed in amblyopia results primarily from an abnormally large number of forward saccades suggests that Amblyopia treatment may improve the self-perception of scholastic competence.”
  • “Data showing that motor skills improve following Amblyopia treatment suggest that treatment may improve the self-perception of athletic and possibly social competence.”

Here is just more evidence to show that the best approach for treating the many visual components of Amblyopia requires a comprehensive model of care, beginning with a comprehensive eye health and vision evaluation and treatment including office-based optometric vision therapy emphasizing binocular vision (stereopsis), oculomotor skills and visual motor skills with a personalized approach to transfer the visual skills being developed into the life of the patient.

For a more detailed look into Amblyopia, diagnosis, advanced treatment and research, go to the VisionHelp Amblyopia Project.

Dan L. Fortenbacher, O.D., FCOVD

The Significance of Retina as Brain Tissue in the Context of Amblyopia

Academy San Antonio

Although recreation and relaxation in Arizona predominated for me this year over attending the meeting of the American Academy of Optometry in San Antonio, I would have loved to attend the session that was held yesterday afternoon.  From the program description:

Binocular Vision, Perception & Pediatric Optometry Section and Vision Science SIG Symposium: Lasker / IRRF Amblyopia Initiative – Where We’ve Been, Where We Are, and Where We’re Going.  This symposium will feature speakers involved in the Lasker/IRRF Initiative: Amblyopia – Challenges and Opportunities. The speakers will discuss recent progress on amblyopia research, the scientific hurdles that have been overcome, and what major questions now confront the field. Moderator: Susan Cotter, OD, MS, FAAO. Speakers: Kevin Duffy, PhD, Earl Smith, III, OD, PhD, FAAO, Benjamin Thompson, PhD, Ewa Niechwiej-Szwedo, PhD, and Ruth Manny, OD, PhD, FAAO.

You can gain a feel for what was discussed from a report published by the Lasker/IRRF Amblyopia Initiative last year — Amblyopia: Challenges and Opportunities.

Lasker Report Cover

There are several sections of the report that have particularly valuable sound bites.  The first relates to an appreciation of the retina as part of the brain.  I’m still hopeful that one of these days we’ll stop referring to “the eye and the brain”, and realize the significance of the eye as integral part of the brain.  So our first sound bit comes from the Concluding Remarks by John Dowling of Harvard’s Center for Brain Science (pages 111-112), who begins as follows:

“All agree that amblyopia is a disorder that affects visual structures beyond the eye. Many say simply that amblyopia is a brain disorder. But the retina is part of the brain, pushed out into the eye during development. As someone who has long studied the retina, I wonder if the retina is at all affected. At first glance, retinal function appears normal in amblyopia, but is it totally unaltered? I am not convinced …”

The second section involves the role of movement in amblyopia therapy (page 97):

“The potential of physical activity to promote amblyopic recovery has caught the attention of the clinical field. Adult subjects who intermittently cycled on a stationary bicycle while watching a movie showed enhanced effects of transient eye patching compared to those subjects who watched the movie while sitting still (Lunghi and Sale, 2015). Moreover, tasks that directly engage both visual and motor circuits have achieved great success in reversing amblyopia. For example, recovery from amblyopia is expedited by tasks requiring coordination of hand and eye movements, such as having patients manipulate objects during visual training (reviewed in Daw, 2013).”

Lastly, with the bolded emphasis mine (page 102):

  • “Novel visual training paradigms that exploit our increased understanding of the biological underpinnings of amblyopia recovery are needed. Future work should continue to seek training strategies that are tailored to the individual patient to engage attentional, emotional, and visuomotor circuits for faster and more effective recovery.”



Amblyopia and Slow Reading

It’s been over a year since I blogged about amblyopia and reading disorders, and the December 2017 issue of the Journal of the American Association for Pediatric Ophthalmology and Strabismus contains commentary on the subject as part of a Symposium on Pediatric Ophthalmology and Childhood Reading Difficulties.

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Insightful observations about amblyopia and slow reading are shared by two Ph.D. researchers, Eileen Birch and Krista Kelly.  Here are some key passages from their commentary:

“Using natural, binocular silent reading of age-appropriate paragraphs of text, we recently reported that children with amblyopia read slowly compared with controls and non-amblyopic strabismic children, regardless of amblyopia type (i.e., strabismic or anisometropic).  Unlike earlier reading studies that focused on strabismus, our study clearly identified that amblyopia alone is sufficient to impair reading. Importantly, comprehension did not differ significantly between amblyopic children and controls, indicating that amblyopic children did not read slowly because they had dyslexia or a learning disability.”

“Unlike dyslexic readers, amblyopic children in our study read more slowly because they made more forward saccades during reading. It is likely that the increased number of forward saccades during reading reflects oculomotor control system deficits. Amblyopia is associated with substantial fixation instability … Taken together, slower saccade initiation, saccade amplitude variability, and increased frequency of secondary saccades can be expected to significantly slow reading speed in amblyopic children.”

“Saccadic eye movements clearly play a key role in efficient reading, a key component of academic achievement. There is a solid evidence base demonstrating slower initiation of saccades and more variable saccade amplitudes in amblyopic individuals. Even though it usually results in poor vision in just one eye, amblyopia can reduce reading speed in natural, binocular reading by 20%-50% and negatively affect academic performance. We have also found that amblyopic children are slower at transferring answers from a standardized test to a Scantron answer sheet compared with visually normal controls. Longer Scantron completion times may exacerbate the problem of slow reading when amblyopic children are administered standardized tests that are time- sensitive, limiting the child’s academic success. The child’s academic achievement, in turn, is a major contributor to the child’s developing self-perception, which has been shown to be affected by amblyopia.  Positive self-perception has an important influence on well-being and quality of life.”

Birch and Kelly conclude:  “While currently there is no evidence that training eye movements will help amblyopic children read faster, parents and educators can work together to implement accommodations (e.g., extra time) to help amblyopic students succeed in their daily school tasks, and improve their performance on the timed, stan- dardized tests that are critical for promotion and admission to magnet schools, TAG programs, high schools, and colleges.”



We could argue over what constitutes “evidence” that training eye movements can enable amblyopic children to read faster (many of our practices are built on such successes), but the take-home message here is that amblyopia is a visual disability that deserves special considerations.  In an invited commentary on Elsevier’s Practice Update for Eyecare, Dr. David Damari, Dean of the Michigan College of Optometry at FSU and a consultant to the National Board of Medical Examiners on Visual Disabilities, noted that the request for accommodations on standardized testing must be documented with performance tests for each individual making such requests.  Which visual performance tests are given weight by testing agencies is an entire subject unto itself.

Screen Shot 2018-02-02 at 11.47.20 AMMuch as CITT-ART is undertaking gold standard research on the transfer effects of training convergence insufficiency to reading, one can anticipate that analogous gold standard research on training amblyopia and its transfer to reading may be undertaken at some point in the future by PEDIG (Pediatric Eye Disease Investigator Group).

Amblyopia success…A family’s amazing vision therapy journey

When it comes to the topic of Amblyopia or “lazy eye”,  the VisionHelp Blog is a good resource for the latest information on diagnosis and advanced treatment. All you have to do is click here for a plethora of our posts!

But, how can you describe the emotional and personal experience that a family goes through, beginning when they first learn that their child has amblyopia followed by the entire process of going through vision therapy? Nothing could possibly say it better than this wonderful heartfelt video, produced by the parents of one of my patients, who wanted to help share their family’s amazing journey and lessons learned about vision therapy with the world. This is their child’s vision therapy success story. Many thanks to Chris and Cindy! 

For more information on the latest advanced treatment for Amblyopia check out VisionHelp Amblyopia Project.

Dan L. Fortenbacher, O.D. FCOVD