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.

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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.

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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

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.

 

(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

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Equipment for Vision Rehabilitation

“What tools do I need to perform basic vision rehab interventions in my clinic?”

The first thing one needs is information. Understanding and Managing Vision Deficits-A Guide for Occupational Therapists would be a wise investment. Dr. Scheiman’s book explains assessing and treating basic binocular vision defects making the subject approachable for therapists. He also teaches a course by the same name that would be a good start.

Vyne Education also offers a course Vision Rehabilitation for Pediatrics-Seeing the Whole the Picture, taught by this author also introduces basic assessment and treating of eye movement disorders.

The Convergence Insufficiency Treatment Trial Manual’s Chapter 8 explains the in-clinic activities used in the CITT and would also be a worth while read.

You will need an optometrist

This may be the hardest thing to find. While the complete binocular vision assessment is the standard of care, frequently this assessment is neglected. Find the optometrist in your community that consistently performs these assessments and you will most likely find a partner. COVD and NORA doctors may be most receptive to working with a physical or occupational therapist that is training in binocular vision disorders.

The optometrist diagnosis is as important as the diagnosis a therapist would get before starting rehab on a shoulder. While we can perform basic testing on a shoulder, some results would indicate further assessment by the orthopedist. Same rules would apply concerning eye movements except that even poor tracking could be caused by a lack of visual acuity requiring glasses (or more accurate glasses).  Always insist that a child have a current eye exam before working on eye movement or even skills like visual motor integration or visual perception. Performance of these tasks requires best corrected visual acuity.

What about Equipment?

The Worth 4 dot   would be a wise first investment. With models starting at about $20, it it also very cost effective and gives great first clues to a eye movement problem.

Marsden Balls offer an easy to use moving target that requires good fixation to read letters. The handy therapist could probably make one on their own.

The Hart Chart is simple way to strengthen accommodation. Do it on a balance board and add in the challenge of balance.

The brock string is a must and its cousin the barrel card can be used to strengthen convergence.  Have the patient make their own brock string becomes a great fine motor activity too.

The Developmental Eye Movement Test is quick to give assessment that gives good data to reading ability and accuracy.

 

Prism and Lenses

The rules governing the use of prism and lenses vary greatly from state to state with the interpretation of the rules varying. Because of this, the author has chosen not to openly recommend these tools. They would generally require being under the supervision of an optometrist or ophthalmologist for there use and purchase.  They also require training to understand the appropriate therapeutic use of these tools.

Be a therapist!

The near-far axis is generally referred to as the Z-axis. When we turn our midline crossing tasks into the Z axis, we are now working the near far visual system.  Check out a previous post here. Be creative and have fun.

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Convergence Tasks for Therapists

The Z axis

As therapists, we recognize the importance of mid-line crossing to help with primitive reflexes.  Reaching lateral outside of the base of support challenges balance and posture.

But to exercise convergence, the therapist must turn their favorite activity into the “Z axis”. This axis is the near-far axis, (referred to as the Z axis in vision) and challenges the convergence and accommodation system.  Many of our favorite activities can be modified just by turning them, to help strengthen the near vision system.

Simple convergence strengthening activities

Clothespins are great therapy tool, strengthening pinch for writing and other tasks. Having a child reach to a distance to retrieve the clothespin then hanging the clothespin on a near string can can help with convergence and divergence. The proprioceptive input of the hand hanging the clothespin on the string will cue the eyes to converge to a point.

The swing adds vestibular and proprioception to the convergence and divergence in this video.

In my clinic, I also use a cup with a straw that patients then put toothpicks in. This task can be graded by moving the cup closer to the child’s face.  This is task also made more difficult by not allowing the kiddo to touch the straw, removing the proprioceptive input,  forcing the eyes to guide the hand more accurately.

 

Amazing creative therapists

Cheerios on a Straw

In the task, the patient puts cheerios on a small coffee stirrer. The hand working at the end of the straw does a great job cuing the eyes to converge. Just make sure the straw stays in at mid-line.

Ball in a Tube

In this task, a 4 ft florescent bulb protector ($4 at Home Depot) is cut in half with a ping pong ball put inside. I then placed stickers on top of the tube. The patient has to align the ping pong ball under the the sticker. In standing? Even better. Balancing on a balance board? Even better!!!

As a bonus, the scrap end of the tube become a great “light saber” for popping bubbles to work on tracking and eye hand coordination.

Thanks to therapists that I have met

The weeks I spend traveling are exhausting but the energy of the people I met help me stay motivated. Thank you to all the therapists and teachers and others, that I have met.

 

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“Can eye movement problems be related to torticollis?”

Ocular Torticollis

Torticollis can be caused by several things. Delays or problems in the integral development of muscle tone, the vestibular system and propreioception can all be causes.  Eye alignment, nystagmus and acuity problems can also affect head position.  When vision is the primary cause for torticollis, it is referred to as ocular torticollis.  One study found 20% of torticollis related to ocular problems. (1)

Eye alignment

Head tilts and head turns are common signs of eye alignment problems. Deviations between eyes in the horizontal plane (hyper- or hypo- tropia) can cause head tilts in the brains attempt to see a single, fused image. Head turns (rotation) to right or left can be caused by strabismus (eso- or exo- tropia). Again, the brain turns the head in attempt to not see double. Other more complex movement patterns can also cause head position and posture problems.

Nystagmus

Nystagmus is an involuntary movement of the eyes. This is generally associated with a neurological problem. They can be congenital or acquired. Many times, patients with a nystagmus will turn their head to find the point at which the nystagmus stops. This point, called the “null point” allows for improved vision for the patient.

Acuity problems

Astigmatism, a condition in which the eyeball is not perfecting round but more football shaped, can also cause visual acuity problems that might facilitate a head tilt in order to improve vision.

Eye Exam

Every child should have their first eye exam at 6 months (per AOA recommendations). A through eye exam that includes a binocular vision exam would find eye alignment problems most likely to cause ocular torticollis.  If treating a patient with torticollis of unknown cause, a binocular vision exam could be helpful in identify the problem. Frequently, prisms and lens can be prescribed that can help reduce the torticollis.

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