“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

Assessing visual fields

Assessing visual field in the OD office

Heres is how visual fields are assessed in the optometry office.

humphery

This is Humphery visual field tester. The test is generally done monocularly first. The patient places their face on the chin rest and clicks a switch when they see a light in the field. The device monitors fixation during the test and lets the tester know if the patient “cheated” by moving their eyes. Binocular testing may be done separately if needed. During this, the patient is allowed to move their eyes.

The results are very precise with even small peripheral reductions in field picked up. But there are some limitations. The patient must be able to respond in a timely manner by clicking a button, so motor response time and even posture can affect the ability to perform testing on this device.

Confrontation Field Testing

Visual field testing by confrontation is a way to perform visual field testing in clinic without the computerized tester.

In the test, the therapist sits in front of the patient presenting fingers in each field with patient reporting the number of fingers up. This is done for each eye.

It is important to present stimulus in all four quadrants of the visual field. Results of this can be correlated with other visual cancellation tests.

There is also campimetry which uses a specialized disk with different fixation points.

photo (15)

With the campimetry device shown above, the patient fixates on numbers on the disk and reports if they can see the middle spot.

There is also a web-based Damato Multifixation Campimeter test for visual fields that is  free.

Types of visual field cuts

Homonymous hemianopia is the most common visual field loss following a neurological event. This is lose of half of the visual field in each eye . These can affect right or left visual field (generally contralateral to the affected side of the brain, left brain right field cut). These tend to be associated with tempro-parieital lobe or occipital lobe damage. Left side field cuts tend to have a neglect aspect associated with them. The patient may not even be aware of the left sided vision loss making treatment of the field cut more difficult. Right sided field cuts tend to be more occipital lobe related with the patient showing improved awareness of the loss and improved recovery. Here is what it would like using a Goldman 30-2 test. This test looks at each eye separately and requires fixation.  The similar patterns in each eye tells us this a visual pathway problem, not and orbit problems.

visualfields-page-003 visualfields-page-002

 

Here is what it looks like on the Easterman Binocular Test. This test uses both eyes, allows for eye movements and is a more functional look at patient useful visual field.

visualfields-page-001

Quadrantanopia is loss of vision in a quadrant of the visual filed (upper right, lower right, upper left, lower left). It can also be homonymous (in both eyes) and may be described a superior right homonymous quadrantanopia.

quad

This is what that might look like.  They might also be bitemporal ( in the lateral fields of both eyes) or binasal (in the medial fields of both eyes)

A central scotoma is is loss of the central visual field and is associated with age-related macular degeneration.

visualfields-page-005 visualfields-page-004

 

 

Visual field treatment

Their are two common strategies behind improving functional status for patients with a field cut. We tend to use a combination of both at the optometry office.

The most common technique is to improve scanning strategies by having the patient perform scanning tasks into the area of the field cut. This can be done with any number of devices such as a Dynavision or a Sanet Vision Integrator. Both of these devices, and others, present random targets in a field with the patients ability to find these targets being timed. With either of these, patient practice scanning strategies which improves their awareness of the field and improves their time locating targets in the missing field.

In optometry, we have other tools available. We can use field expansion systems such as the Peli-lens or Gottlieb Field awareness system. Both of these involve the application of small pieces of prism to the lens of the patients glasses. These small strips move visual stimuli into the patient’s existing field “reminding” them to look to the affect side.  They cue the patient to scan into the missing field, something like a warning system.

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Balance and Vision

 

Two Visual Pathways

The focal, central or Parvocelluar visual system is called the “What” vision system. It is responsible for object identification. It allows us to focus on a specific object in the visual field. This information is interpreted in the occipital lobe.

The ambient/peripheral or Magnocellular visual system is the “Where” system responsible for spatial information, balance, coordination and peripheral awareness. This information is shared with the occipital lobe, in addition to links to the cerebellum and balance areas of the brain. Functional MRI shows this information actually reaching 99% of the cortex. Using ambient vision, we can automatically change our posture and gait to walk uphill or protect ourselves from falling over as someone bumps into us.

Functionally, these two systems allow use to look at the road ahead of us (focal vision) and be aware of the car to our left(ambient). It also allows us look at the TV but be aware of where the door in the room is. It allows us to be focused on a word in reading, but still make accurate saccades to the next word.

Notice what happens to the people attempting to walk through the tunnel.

Notice how the people in the tunnel are leaning to one side. The tunnel walls have confused their ambient vision system and affected the gait and balance.

A tool for rehabilitation…

Frequently this system can become faulty following a neurological event. In a condition called Post Trauma Vision Syndrome”, patients become over-centrally focused. This is seen clinically as decreased balance, decreased reading accuracy and poor spatial awareness a midline shift or toe/heel walking.  The patients also report becoming “over-stimulated” by visual information.   A visual field done a patient with this condition might look like this

peripheral loss

This is one eye, but the other may look the same. Notice the reduced periphery that might not show up in typical in-clinic screening of visual fields.  This visual field test is called a Goldman 30-2 and is done on each eye.  It  should be a standard part of the assessment of all of the post-TBI/CVA patients.

Improving Ambient Visual Function

To improve function of the ambient system, binasal occlusion may be added to a patients glasses with or without mild base in prisms.  How does this help?

A person that is over-centrally focused has a difficult time seeing the entire word. They tend to see letters rather than the whole word which greatly reduces reading fluency and comprehension. Saccades also become less accurate due to the decreased awareness of the line of text  making the person lose their place frequently.

This can also improve posture and gait. As the brain becomes more aware of the ambient visual system, it is better able to correctly adjust gait and posture. Remember the tunnel?

Optometrists that offer this type of service are involved in neuro-optometry. The organization is called the Neuro-Optometric Rehabilitation Association. This is a multi-disciplinary organization that was started by ODs who wanted to understand brain injury better and exchange information with other providers of care in the  TBI community like OTs and PTs. There is a provider list on their website to help you find a NORA optometrist in your area.

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How do we see up close?

The Near Vision System

“I can’t see the board” is a common reason children come for their first eye exam. But problems seeing up close are more closely related to academic success than distance vision problems. With more computer use, and frequent changes from looking at the board to a notebook, school can be a workout for the near vision focusing system.

Watering eyes, rubbing eyes, and headaches are early signs of problems with near vision. These soon lead to difficulty reading and falling grades. The child may also show avoidance behaviors when trying to do school work as it is physically painful to see up close. But worst of all, the child may not say anything at all, as they do not know that their vision is not working right. Typical school vision screenings may miss the problem also.

The near vision system is a balance of several processes…

So what are the mechanisms involved in near vision focusing??

There are 3 processes involved in near vision focusing. Optometrists call it the near vision triad.

1) Pupil constriction- as an object moves closer, the pupils constrict to improve focusing of incoming light on the fovea. The fovea is an area on the retina with the highest density of light receptors. This area gives us our most acute vision.

2) Convergence– as an object moves closer, the eyes move toward the nose to keep the object on the fovea. Both eyes should smoothly convergence together as the target moves closer.

3) Accommodation– lens of the eye focuses- In humans under 40 years old, the lens of each eye changes focus as objects move closer. This is much like a camera lens. As children, the lens is very flexible allowing for a large focusing range. After 40, the lens tends to become less flexible, so we may need glasses to help see clearly up close

Heres a video that puts it all together.

As something moves toward us, the brain adjusts with the right amount of accommodation and convergence, in addition to the pupil constriction.

What does it look like when it does not work right??


This is easy to screen using the Near Point Convergence test .  

Only the optometrist can identify these problems, but as therapists, teachers and parents, we need to be aware of the signs of near focusing problems. The Convergence Insufficiency Symptom Survey  is a well researched tool that is very effective in identifying patients with possible CI.

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Learn more about this subject in a live course and webinar presented by Robert. Hosted by PESI Education

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