The Functional Effects of Nystagmus

What is nystagmus?

Nothing can appear so disruptive as eyes that are constantly moving. Therapist’s become very concerned as they attempt to imagine how a child with nystagmus sees the universe and the functional affects of these constantly moving eyes.

Nystagmus is an involuntary movement of the eyes. While most are in a horizontal plane, the nystagmus may be vertical, or even rotary.

The nystagmus may be defined by the time of onset.

  • A congenital nystagmus is present at birth or develops in the first six months after birth.
  • An acquired nystagmus develops later in life and may be assist with multiple sclerosis, brain injury or drug and alcohol use. (1)

The nystagmus may be further defined by the type of movement observed.

  • A “jerk” nystagmus is slow in one direct and fast in the other
  • A “pendular” nystagmus is the same speed in both directions
  • A “rotary nystagmus” has the rotating on the Z-Axis

The cause of most congenital nystagmus is may be associated with:

  • retinal disorders leading to low vision
  • Albinism
    • Albinism has several vision related co-morbidities including low vision and retinal problems, which may be present as well(2)
  • a family history of nystagmus
  • neurological problems at birth

These conditions may lead to life long nystagmus causing social as well as low vision related problems (3)

There are not many effective treatments for nystagmus with medications (gabapentin and memantine) emerging as helpful in some cases. (6)

Here are some videos with examples of nystagmus

Adaptation to nystagmus

Children with congenital nystagmus do not see the world moving constantly. The brain develops with this occurring and adapts though the child may need glasses to get their best vision. There is evidence that congenital nystagmus has little effect on reading performance(4), while another study suggest “crowding” could be a problem decreasing reading performance(5).

The initial adaption to an acquired nystagmus is location of the “null point”. This is a head position in which the nystagmus is reduced or eliminated. This may be perceived in child as a torticollis making an eye exam critical in children with torticollis. Surgical intervention may be used to realign the eyes to “move” the null point to allow for a better head position.

What do we do to help?

There is no effective therapeutic treatment a PT or OT can do to reduce a nystagmus. The child should be in best corrected visual acuity to use his vision most effectively. Know that the child with congenital nystagmus does not perceive the world as bouncing around. It becomes the job of therapist to make sure those usual developmental skills are learned or adaptations made for low vision as needed.

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(1) Does your child have involuntary eye movements (nystagmus)? (n.d.). Retrieved from https://www.allaboutvision.com/conditions/nystagmus.htm

(2)Summers, C. G. (2009, June). Albinism: Classification, clinical characteristics, and recent findings. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/19390472

(3)Pilling, R. F., Thompson, J. R., & Gottlob, I. (2005, October). Social and visual function in nystagmus. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/16170116

(4)Barot, N., McLean, R. J., Gottlob, I., & Proudlock, F. A. (2013, June). Reading performance in infantile nystagmus. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/23462273

(5)Huurneman, B., Boonstra, F. N., & Goossens, J. (2016, August 01). Perceptual Learning in Children With Infantile Nystagmus: Effects on Reading Performance. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/27548897

(6)Papageorgiou, E., McLean, R. J., & Gottlob, I. (2014, October). Nystagmus in childhood. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/25086850

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Is it ADHD or near vision problems?

Whats up with Bryson?

Here is the story of our hypothetical friend, Bryson. Bryson is in second grade now but he had a tough time in first grade with reading and hand writing. He just “made the cut” to get promoted to second grade but now he is falling behind. He hates reading. It hurts his eyes when he reads and he has a hard time seeing the words. He doesn’t know that words aren’t supposed to be blurred and moving around when you read. It is the only way he has ever seen them.

Ms. Clark, his teacher, passes out a reading sheet to the class. It is a short paragraph with a few sentences and a few questions about the paragraph. Bryson gets his paper and starts to read the paragraph, but the words are blurry and his eyes hurt as he tries to complete the reading. He keeps lifting his head up from the paper because that seems to make his eyes hurt less. He is getting nervous though because he hasn’t finished the reading and he knows Ms. Clark will be asking for the paper soon. When he gets nervous, Bryson fidgets at his desk and finds it hard to sit still.  Ms. Clark asks for the papers to be passed forward and Bryson hasn’t answered any questions correctly about the paragraph.

Next, Ms. Clark is going to have the children take turns reading aloud. Bryson doesn’t like this at all. He doesn’t read as well as the other kids and it makes him really anxious. As it gets closer to his turn to read, Bryson’s neighbor reminds him of how much trouble Bryson had when they did this last time. Bryson hollers at his neighbor ,”Shut up!”. This interrupts the class and Bryson gets in trouble.

Ms. Clark

Ms. Clark is great teacher and watches Bryson. He seems really smart, but while he is supposed to be reading, Bryson is looking around the classroom and not getting his work done. He has a lot of difficulty sitting still during the school day and he has had some difficulty with interrupting the classroom. Bryson looks like a child with ADHD. She talks with Bryson’s mom who doesn’t see much of this at home, but does know that Bryson hates home work. He spends hours trying to complete reading assignments but no matter how he works, he still has difficulty.

Off to the Pediatrician

So Bryson’s mom takes him to the pediatrician and discusses her concerns with doc. The doctor completes an ADHD behavioral scale and Bryson does score high enough to be diagnosed with ADHD. The doc starts him on a typical ADHD med. After a week on the medication, the teacher and mom are not seeing much change so the doc tries another medication. This also does not seem to be helpful.

Is it ADHD or near vision focusing problems?

Several studies have shown that the behavioral symptoms of near vision focusing problems are frequently mistaken for ADHD(2).  In fact, one study showed that children with near vision focusing problems score higher on ADHD scales than children with ADHD!(1)

But Bryson went to the eye doctor and they said his vision was fine…20/20… he didn’t even need glasses! This is common with children with near vision focusing problems. Typical eye exams may not find this problem, so a child may stay on medication for years and struggle with academics.

Of course not all ADHD is a near vision problem, but children with ADHD do tend to have a higher incidence of eye movement problems. While vision rehabilitation can help with these eye movement problems, it does not treat ADHD.

Binocular Vision Exam

Only a binocular vision exam will reveal the problems with Bryson’s vision. Only in-clinic treatment for his near vision focusing problems will correct his problem (3). Ask your eye doctor if this exam that will performed!

Learn More

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(1)Rouse, M., Borsting, E., Mitchell, G. L., Kulp, M. T., Scheiman, M., Amster, D., . . . CITT, G. R. (2009, October). Academic behaviors in children with convergence insufficiency with and without parent-reported ADHD. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/19741558

(2)Borsting, E., Rouse, M., & Chu, R. (2005, October). Measuring ADHD behaviors in children with symptomatic accommodative dysfunction or convergence insufficiency: A preliminary study. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/16230274

(3)Scheiman, M., Mitchell, G. L., Cotter, S., Cooper, J., Kulp, M., Rouse, M., . . . Convergence, G. R. (2005, January). A randomized clinical trial of treatments for convergence insufficiency in children. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/15642806

 

Visual Perception

Of visual perception

There are many assumptions made about a student’s performance on visual perception tests. After all, these tests give norm’ed results which can be helpful in goal making and identifying a potential cause for an academic problem.

But do the results actually reflect visual perpetual skill?

Many factors can hamper the reliability and validity of visual perceptual testing.

  • Visual acuity-is this patient in best correct visual acuity? Have they had an eye exam and been prescribed the appropriate glasses? Do the glasses fit well to allow for the intended benefit?
  • Binocular vision skills?-Poor binocular vision skills can result in double vision and blurred vision up close which can affect the results of visual perceptual testing?

These two factors, when not corrected, make for a “garbage in-garbage out” situation and taint the results of the testing, increasing the likelihood for invalid results in the patient.

Imagine putting a glove on a patient then asking that patient to identify coins that they are holding in the gloved hand. They would have a difficult time doing this, not because of an inability to process the feel of the coin, but because the stimuli to be interpreted is muted. It becomes difficult to process to the correct conclusion when the initial stimulus is faulty.

Behavior and cognition matter too

With best corrected acuity and good binocular visual skills, other factors, such as attention can play a role in visual perceptual testing. Common visual perceptual tests can take as long at 45 minutes of monotonous testing making even the most attentive children bored and possibly affecting results.

Most visual perceptual tests are designed so the child with a visual perceptual problem misses three consecutive items in a section, then advance forward to the next section. The pattern is irregular (child misses one item then 3 correct then misses two items, then one correct) perhaps attention is playing a role in the test results.

Visual Percetual Testing

In my clinic, I do not test visual perception until after binocular vision issues have been corrected and the patient is in best corrected visual acuity.

With these things in place, you will find visual perception intervention much more effective and testing will be more valid and reliable.

Learn More

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“Is it a vision problem?”

Does this child have a visually-based problem?

Our children present with a vast array of problems affecting their development and academics. Sensory problems, trauma, autism, behavior, ADHD and the list goes on. Our children get assessed by OTs, and PTs, neurologists, neuropsychologists, and pediatricians. But did they have an eye-exam? A complete eye exam? Only 40% of children have had their eyes examined by an eye doctor. (1) That leaves all of those children potentially walking around with vision problems affecting their academic and developmental development. Meanwhile, we attempt to teach them catch a ball or write the alphabet or button a button.

“Does he need an eye exam?”

YES!!! Every child, regardless of academic performance or other diagnosis, needs a complete eye exam with a binocular vision assessment and cycloplegic dilation, even if the child has never complained about their vision.  Many times, when a child is assessed with the Convergence Insufficiency Symptom Survey, they learn that they are not supposed to see “words moving” on the page or see double when they read. They had symptoms and were not even aware. Most children with ocular motor or near vision problems will read letters on a chart without difficulty. 20/20 means only that each eye has good acuity. It does not tell us how well the eyes are working together or how hard the eyes are working to make a 20/20 acuity. Only a complete eye exam with binocular assessment and cycloplegic dilation can give the whole picture.

“Is this is visually-based problem?”

There are many signs a child is having a visual-based problem.

  • Eye rubbing
  • unexplained headaches
  • poor handwriting
  • poor reading skills that do not improve with tutoring
  • head turning or tilting when reading
  • closing one eye while reading
  • poor visual motor integration that does not improve practice
  • poor balance or motion sensitivity
  • Diagnosed ADHD that does not respond to medication
  • unable to catch a ball
  • letter reversals
  • visual perceptual problems
  • spacing and size problems during handwriting tasks
  • fine motor delays
  • poor depth perception

These problems maybe mis-diagnosed as things like dyslexia or ADHD and even be treated as such without success for many years.

“Who do I send them to, to make sure they a complete eye exam?”

A good place to start is College of Optometrists in Visual Development. These doctor specialize in the assessment and treatment of eye movement disorders and near vision focusing problems that could be affecting academic performance. You can your local COVD doctor with the search tool on the site. One might also look for an optometrist that specializes in pediatrics or binocular vision.

When an appointment is made, be specific about symptoms and ask for a “binocular vision assessment”.

Every child

Every child needs a complete eye exam. Parents may have many reasons to not get this dome, but you cannot teach a child read or write, or catch a ball that cannot see.

Learn More

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1.Children’s Vision Screening and Intervention. (n.d.). Retrieved from https://nationalcenter.preventblindness.org/childrens-vision-screening-and-intervention

Autism and Vision

Autism and Sight

There has been several recently published articles on autism with some dysfunctions being found at a higher rate than in the neuro-typical population. One study, published in January 2017, found consistently that children with autism reacted slower to changes in light (pupillary light reflex). The pupillary light reflex was slower when lighting changed and, in darkness, the pupil measured smaller than controls.(1)

A second study, published in 2018, found a higher rate of accommodative problems (17.4% for ASD, vs 4.9% control) for children diagnosed with autism. While there was no substantial difference in the rate of refractive error, this higher rate of accommodative problems makes a complete eye exam with assessment of near vision acuity more important.(2)

A review of evidence found several contradictory studies concerning the prevalence of eye movement defects associated with autism, though most agree that saccades inaccuracy as well as difficulties in tracking are common in ASD. These movement problems, coupled with other fine and gross motor deficits found in autism suggests a cerebellar problem.(3)

Autism and Vision

Difficulties with the integration of visual information is found in several studies. All of these studies point to a lack of integration between the parvocellular and magnocellular tract and reduced communication between these tracts.(3)

Studies found differences in VEPs (visually evoked potentials) studies in the activity of the magnocellular tract compared to neuro typical children. The difference was, most notably, a slower recovery period for the magnocellular tract and therefore, decreased integration of the information. Functionally, this may help explain the visual spatial problems frequently seen in ASD diagnosed children. (4, 5)

Lateral gazing’ behavior was also found in some children with ASD as they attempted to use peripheral vision to reduced central visual pathway input. (3) This behavior is also suggestive of magnocellular tract deficits.

Integration Deficits

A common thread through many of these studies is a decreased integration of visual information and motor pathways and the cerebellum. (6) This lack of integration could help explain the ocular motor and saccade problems, as well as increased incidence of gait problems and toe walking (7,8) and visual motor integration problems found in children with ASD. A study also showed that people with ASD do not make good use of visual information to correct posture (9). Addressing this lack of integration could be helpful making functional progress with children on the spectrum.

Summary

A complete binocular vision exam with cycloplegic dilation is very important for every child with autism (and neuro typical children too) given the potential for a higher rate of accommodative and ocular motor problems and fine motor, reading and handwriting problems.

Given the evidence of integration problems, activities for children with ASD should be “top down” type activities that require the integration of movement and vision.

Much of this research is very recent and found some changes from previous research. Many of the studies suggested these differences in results were related to redefining autism with the release of DSM-5 eliminating Aspergers and pervasive developmental disorder and grouping these into the current terminology of autism spectrum disorder. The inclusion of these subjects in studies have helped improve the understanding of vision and autism. Many of the studies also sited small samples as potential limitations.

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(1)Anketell, P. M., Saunders, K. J., Gallagher, S. M., Bailey, C., & Little, J. A. (2018, March). Accommodative Function in Individuals with Autism Spectrum Disorder. Retrieved March 05, 2018, from https://www.ncbi.nlm.nih.gov/pubmed/29424829

(2)DiCriscio, A. S., & Troiani, V. (2017, July 25). Pupil adaptation corresponds to quantitative measures of autism traits in children. Retrieved March 05, 2018, from https://www.ncbi.nlm.nih.gov/pubmed/28743966

(3)Bakroon, A., & Lakshminarayanan, V. (2016, July). Visual function in autism spectrum disorders: a critical review. Retrieved March 05, 2018, from https://www.ncbi.nlm.nih.gov/pubmed/27161596

(4)Jackson, B. L., Blackwood, E. M., Blum, J., Carruthers, S. P., Nemorin, S., Pryor, B. A., . . . Crewther, D. P. (2013, June 18). Magno- and Parvocellular Contrast Responses in Varying Degrees of Autistic Trait. Retrieved March 05, 2018, from https://www.ncbi.nlm.nih.gov/pubmed/23824955

(5)Sutherland, A., & Crewther, D. P. (2010, July). Magnocellular visual evoked potential delay with high autism spectrum quotient yields a neural mechanism for altered perception. Retrieved March 05, 2018, from https://www.ncbi.nlm.nih.gov/pubmed/20513659

(6)Miller, M., Chukoskie, L., Zinni, M., Townsend, J., & Trauner, D. (2014, August 01). Dyspraxia, motor function and visual-motor integration in autism. Retrieved March 05, 2018, from https://www.ncbi.nlm.nih.gov/pubmed/24742861

(7)Accardo, P. J., & Barrow, W. (2015, April). Toe walking in autism: further observations. Retrieved March 05, 2018, from https://www.ncbi.nlm.nih.gov/pubmed/24563477

(8)Kindregan, D., Gallagher, L., & Gormley, J. (n.d.). Gait deviations in children with autism spectrum disorders: a review. Retrieved March 05, 2018, from https://www.ncbi.nlm.nih.gov/pubmed/25922766

(9)Morris, S. L., Foster, C. J., Parsons, R., Falkmer, M., Falkmer, T., & Rosalie, S. M. (2015, October 29). Differences in the use of vision and proprioception for postural control in autism spectrum disorder. Retrieved March 05, 2018, from https://www.ncbi.nlm.nih.gov/pubmed/26314635

The Hart Chart

Accommodation

Accommodation is one of the mechanisms that allow us to see up close. Accommodation is the focusing of the lenses in each eye. This action, combined with the convergence, allows for us to see clearly up close. 

Accommodation is the result of the contraction of the ciliary bodies in the eye which allow for the lens to get thicker thereby focusing the image better in the fovea. This action also includes the constriction of the pupil which more precisely focuses the light on fovea making the image sharper. Here is video of this in action

 

“Its blurry up close”

When accommodation does not work, one may see blurry up close, get headaches or rub the eyes due to eye strain. The ciliary muscles attempting to make the image clear, causes this discomfort discomfort. Accommodation can be exercised to strengthen it to improve near vision. This is generally performed in conjunction with convergence exercises to improve near vision  when one treats convergence insufficiency.

The Hart Chart

A simple way to improve convergence is using a Hart chart. With this activity, a grid of letters is placed at distance and one is held by the patient, near. The patient then reads a line close (or letter) then a line at distance. This is done with one eye occluded so the accommodative action is exercised as the eye focuses near then far. In my clinic, this performed while standing on balance board to further challenge the patient. This simple activity is quite effective at strengthening accommodation. A Hart chart can be purchased from Bernell, found on the internet and is included on the Vision Rehabilitation for Pediatrics Course Companion flash drive. Heres a video.

The Hart chart is one way accommodation can be strengthened. In optometric vision therapy, lenses can be used to strengthen accommodation using an activity called Accommodative Rock.

Support your local Optometrist

A complete binocular vision assessment should be conducted before performing these tasks to make sure that are appropriate. Only an ophthalmologist or optometrist can accurately diagnose an accommodative problem.

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Fine motor skills and vision

Does binocular vision affect fine motor ability?

Occupational therapy has been treating fine motor problems since the beginning of the profession. From tying shoes to buttoning to handwriting, when children or adults have difficulty with this, occupational therapy is referred.

Binocular vision?

A small study (1) looked at the fine motor skills of children with reading difficulties and found those with fine motor problems also had binocular vision problems, specifically accommodative problems.  While a small study (19 children), this suggests that vision is playing a role in fine motor coordination.

Another study (2) found that children that were poor readers showed a higher occurrence of binocular vision difficulties and suggested a need for the assessment of these skills in problem readers.

Research also indicates the importance binocular vision and motion perception to development of the motor skills(3) as young a 2 years old.

OT and binocular vision

As therapists, we are seeing children with difficulties that could have a binocular vision component. While a through binocular eye exam should be completed to rule out treatable defects, therapists integrating tracking, saccade and convergence activities could help improve outcomes for their patients. Our background in developmental sequence, kinesiology and assessment of functional ability make therapists the perfect profession to address these deficits. As therapists, we address the motor part of visual motor problems, but basic tracking, eye-hand coordination tasks could help with outcomes by improving the visual aspects of this skill.

The Therapist/OD team

Therapists, both PT and OT, should get the training to feel comfortable integrating these simple tasks into the interventions they already perform. Next, reach out to optometrists in their area. This relationship will be beneficial for both the therapist and optometrist, but mostly, this will help the patient.

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About the Author

Learn more about this subject in a live course and webinar presented by Robert.  Its now available as a webinar too!! Hosted by PESI Education

(1)Niechwiej-Szwedo, E., Alramis, F., & Christian, L. W. (2017, October 27). Association between fine motor skills and binocular visual function in children with reading difficulties. Retrieved November 13, 2017, from https://www.ncbi.nlm.nih.gov/pubmed/29096178

(2)Palomo-Alvarez, C., & Puell, M. C. (2010, June). Binocular function in school children with reading difficulties. Retrieved November 13, 2017, from https://www.ncbi.nlm.nih.gov/pubmed/19960202

(3)Thompson, B., McKinlay, C. J., Chakraborty, A., Anstice, N. S., Jacobs, R. J., Paudel, N., . . . CHYLD, T. E. (2017, September 29). Global motion perception is associated with motor function in 2-year-old children. Retrieved November 13, 2017, from https://www.ncbi.nlm.nih.gov/pubmed/28864240