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EYE TRACKING / EYE HAND / VISION & VESTIBULAR / VISUAL MOTOR SKILLS

Establishing good Visual Posture, Orientation, and Stability for Vision Tasks

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Alan P Pearson OD PhD FCOVD

August 15, 2021


AT-A-GLANCE

  • We need eye movements because the most sensitive part of our vision is our precise straight ahead looking involving the eye's fovea.  We have to move this fovea so it is pointing directly at the targets we are looking at.
  • Eye movements happen in the head, but the head is balanced on the neck which is balanced on the trunk, which is balanced on the legs, which are balanced on the ankles, so eye movements have to be coordinated together with all these other body orientations and balancing acts.
  • To diagnose visual orientation and eye movement disorders takes testing that usually goes beyond a standard regular eye exam.   A Functional Vision Evaluation involves more involved functional testing of visual performance in body movement.
  • Treatment of visual orientation and eye movement disorders requires a therapeutic approach combining in-clinic visits with prescribe home activities to practice.  At Vision Clinics of Development & Learning we use software that assists in the motivation and compliance with the home prescription.

WHY DO WE NEED EYE MOVEMENTS?

We need eye movements because we have a fovea - a very small sensitive area of detail detection in the back of our eyes. Unlike a camera which collects equal information in the periphery compared to the center, our eyes have many more cells in the fovea area collecting central information for object detail and fewer cells in the peripheral. When you look directly at an object you can see it most clearly, but if you look only slightly to the side it begins to blur. This means that in order to see the greatest detail for best identification of the target, we have to move the eye in order to orient the fovea on the item of interest.  Because we have a fovea we need eye movements.   Good body orientation and precise eye pointing at targets are essential for most any activity we do in life. 

We are much more complicated than an imaginary tree with eyes.  Such a tree with eyes has a solid trunk and no neck.  Only the eyes move.   Human beings, on the other hand, have eyes that are in a head that balance on a neck which then balances on a trunk, which then balances on legs, that finally balance on ankles.  And we have two feet neither of which are rooted in the ground.   So you can see, it is quite a balancing act.  It is like a stack of triangles with the two eyes at the very top.  Unless all the triangles are perfectly balanced, the eyes are going to have a difficult time pointing at anything. 

EYE MOVEMENT & TRACKING DIFFICULTIES

Eye movement & tracking difficulties are usually problems with integration of our vision, vestibular (inner ear body balance system), and proprioceptive (body, joint, and muscle senses).  When there are problems with integration it can be difficult to get the body in good orientation, or maintain good orientation in a vision task.  First, the body and head has to be turned towards the vision task to get the eyes pointing in the general direction.  Second, the eyes have to precisely point exactly at the object being viewed.  Good body orientation to a task is an essential prerequisite for good two eye coordination and visual information processing.  Children and adults who can't orient well to a task may not have quality learning moments or productive work and thus may not achieve to potential.  Hyperactivity, where the body is in constant movement, may not allow detailed information gathering due to poorly stabilized eye pointing.   An overly relaxed, or low tone body, can likewise interfere with detailed information gathering as there may be too much "slack" in the body that needs to be picked up before good eye pointing can happen.  

Most of these body orientation and eye pointing functions happen in the background unconsciously so that our conscious thinking can be about what we are looking at, not about how we are looking at it.   In adults who have had a concussion or acquired brain injury these eye movement functions and integration with balance and muscles may suddenly become dysfunctional and no longer function automatically in the background.  This can be very disruptive and make it impossible to accomplish basic tasks with the body and eyes that were so easy prior to the accident. 

DIAGNOSING ORIENTATION AND EYE MOVEMENT DISORDERS

A Functional Vision Evaluation is necessary to diagnose visual orientation and eye movement disorders. Regular routine eye exams emphasize eye health and eye optics and often do not delve deep enough into functional vision and symptoms unless the patient specifically expresses problems, asks questions or has concerns.  And for those children and adults that have just learned to avoid a lot of hard activities they may not have many symptoms or concerns but still be falling behind in their achievement potential due to problems.  In order to function well, the eyes need  to be healthy and any need for eyeglasses should be taken care of.  Next, a Functional Vision Evaluation will take an in-depth assessment of visual orientation, eye tracking, binocular vision, and eye focusing in the context of the visual challenges the individual faces in development, school, work, or recreation.

Visual orientation and eye movement disorders come in a variety of types that identify one part of the visual system that is dysfunctional. But in the end most cases involve aspects of all parts of the visual system, such as two eye coordination, eye focusing, and eye tracking working together in an integrated and efficient manner.   Some various types are:

  • Fixation or Gaze Stability difficulties: being able to maintain precise eye pointing on a steady target
  • Pursuit eye tracking difficulties: maintaining eye pointing on a moving target
  • Saccadic eye tracking difficulties: jumping eye movements from one target to another
  • Visual-Vestibular difficulties: Integration of balance, joints, muscles, and vision
  • Nystagmus:  A jerking eye movement that interferes with function
  • Retained Reflexes: Parts of the body move together when they should function independently
  • Bilateral Coordination: Difficulties coordinating the two sides of the body
  • Visual-Motor Integration / Fine Motor difficulties: Such as directing a pen or pencil to form letters
  • Rhythm and Timing:  Coordination of movements that depend upon good timing

Only an eye doctor (Optometrist or Ophthalmologist) has the tools to perform a Functional Vision Evaluation and diagnose eye movement disorders. Not all eye doctors have the interest or training to perform a Functional Vision Evaluation.  If you are living in Washington State, USA near the Bellevue or Bothell area, you can schedule a Functional Vision Evaluation at the Vision Clinics of Development & Learning [www.visioncdl.com].  If you are reading this from afar, then the following directories can be helpful in locating a doctor who can perform a Functional Vision Evaluation:

College of Optometrists in Vision Development:  www.covd.org

Optometric Extension Program Foundation:  www.oepf.org

Neuro-Optometric Rehabilitation Association:  www.nora.cc

THERAPY FOR BODY ORIENTATION AND EYE MOVEMENT ISSUES

Rarely are eye tracking difficulties limited to just the eyes.  Almost always the issues include integration with the entire muscle system of the body and the other senses, especially the sense of balance (vestibular).   Therefore there are several professionals that work with the body in ways that can improve and impact body orientation and eye movements.   Some of these include:

  • Physical Therapy
  • Occupational Therapy
  • Vision Therapy
  • Physical Education / Sports & Conditioning

At the Vision Clinics of Development & Learning we specialize in vision therapy but we often coordinate and collaborate with other professionals also working with the patient.  Vision therapy is the process by which integration between vision, balance, and muscles of the body can be improved or rehabilitated.  Since there are so many individual differences when it comes to visual orientation and eye movement disorders, it is not possible to make a general statement on how long therapy will take, but a good rule of thumb is that there should be significant improvements over a 4 to 6 month period of therapy.   The best approach to therapy is to combine once per week clinic visits with prescribed home activities that are completed 5 times per week.     For more information or appointment call (425) 213-1016

INSURANCE COVERAGE

Body orientation and eye movement disorders may be covered by an insurance plan using the physical medicine codes similar to occupational or physical therapy.  When there are also two eye coordination difficultes (very often the case) then specific vision therapy codes may also be used.   There are too many variations among insurance plans and patient situations to determine coverage generally and insurance coverage cannot be guaranteed. Even with an insurance plan that says they "cover" treatment, you may still find there are large copays, deductibles, and coinsurance to deal with before you realize any benefit.  Almost no insurance plan will cover the entire costs for a treatment plan even if they say you have coverage.  For example, software and other prescribed home therapy equipment and monitoring is usually paid privately or through a flexible spending account.   Also, even when an insurance plan covers vision therapy treatment sessions they typically only cover a 30 minute appointment.   Progress visits are medical doctor visits so they are more frequently covered with less problems.  

Some insurance plans have specific exclusions for "Vision Therapy" , but they may cover once per month doctor's visits for an at-a-distance program.  Some plans will have coverage for occupational or physical therapy, but not vision therapy, in which case collaboration with an occupational or physical therapist and completing as much as possible at home makes a lot of sense.   You will have to look up the details of your insurance plan to determine if there are such exclusions for vision therapy.  Sometimes it is hard to find such information and it becomes necessary to call your insurance plan to ask them specifically.   Here is the question you can ask them that has the proper language and codes:  "Does my insurance plan cover vision therapy or orthoptics  92065?"  and then ask "are there any exclusions of vision therapy for my plan?"  and finally ask:  "are there any prior authorization requirements?".  Remember, you have to first complete a Functional Vision Evaluation to reach an official diagnosis and prescribed treatment plan, and even if seems like it should be covered there can still be obstacles and coverage is never guaranteed.

NOTES

There are many other visual dysfunctions that can occur simultaneously with visual orientation and eye movement disorders.   For example, eye optics, two eye coordination problems, eye focusing problems, and visual perception and processing problems. Treatment of visual orientation and eye movements alone is not meant to address these other problems. Some of these other problems may need to be addressed before treatment can begin. Some of the problems can be addressed simultaneously with treatment.   The eye doctor will determine the best strategy, sequence, and emphasis in treatment plan selection.

www.visioncdl.com   info@visioncdl.com   425-213-1016

©2018 Vision Clinics of Development & Learning



 


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