Tag pediatric optometry

“Can eye movement problems be related to torticollis?”

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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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Worth 4 Dot

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Worth 4 Dot

The worth 4 dot is simple tool for assessing suppression and fusion. The results oworth4dotf the quick assessment can give us clues to the function of the eyes. The worth 4 dot (W4D) test is is made up of a pair of red-green glasses and light with 4 dots, 2 green, one red and one white.

The patient puts on the glasses and the light in placed near (40cm or less) and asked how many lights they see.  It is then moved to distance (1 M) and asked once again how many lights are seen.

W4D Responses

There are 4 appropriate responses. Other responses should be considered a failure of the patient to understand the instructions.

  1. 4 lights, near and/or far indicate using both eyes. I will ask if the lights are moving or not to see if the fusion is steady.
  2. 3 lights or two lights- three light indicates suppression of one eye. Which eye depends on the red green arrange of the particular test one is using. They may suppress at near or far or both, so an answer of 3 close and 2 far would be appropriate.
  3. 5 lights- a response of 5 lights indicates the patient is having double vision at the range. It may be near or far or both.

The W4D is usually the first test I do as it gives me early clues what to look for as I begin looking at eye movements. This test can also indicate how a patient may do on stereopsis testing as suppression of of an eye could me reduced stereopsis.

Getting a Worth 4 Dot

Worth 4 dot is available from Bernell.com. There are several version but the idea is the same for all.

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The Binocular Vision Exam

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The Child’s Special Visual System

Children’s eyes are amazing. They bring the world to an eager child and facilitate development of many skills.  The visual world influences posture and gait, fine motor development, letter recognition on to reading skills and many other areas.  The importance of good vision cannot be over stated.

The Pediatric vision exam

The vision exam for a child should include assessments not generally not performed on adults. Check out this post first to understand how we see up close. 

  • Cyclopelgic Dilation and Refraction- This allows for the doctor to completely exam the retina of a child for optic nerve problems and other congenital problems that child may have. The cyclopelgic dilation also relaxes the ciliary muscles which control accommodation (focusing of the lens within the eye). This allows the doctor to exam the true refractive error of the eye which can frequently be corrected by the accommodation of the lens.  This should be considered mandatory once a year.
  • Near Point of Convergence – This brief assessment allows for the doctor to assess how how well the eyes are working together when seeing up close.
  • Measured cover test- A cover test reveals the amount of effort needed for the eyes to maintain their position. It also shows subtle eye movement problems like strabismus.
  • Retinoscopy – in this assessment, the doctor can get an objective measurement of refractive error. This eliminates communication problems some children may have and makes for the most accurate solution for a child;s visual acuity.

Better or Worse

General optometrists and opthamologists may or may not perform these tests.  Without them, an important part of the assessment of a child’s vision has been left out. Eye movements can cause delays in gross and fine motor development and decreased reading performance and difficulty in sports, like hitting or catching a baseball.

Look for doctors that advertise being pediatric or binocular vision specialist. Look for doctors that members of the College of Visual Development or the Neuro – Optometric Vision Association.  These are doctors that specialized in the assessment of binocular vision skills.

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ADHD and Eye Movements

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ADHD and Eye Movements

There is much research concerning the link between eye movements and ADHD. Researchers consistently find specific eye movement behaviors associated with ADHD. But how does this research help in the clinic?

ADHD and Saccades

Much of the ADHD/Eye movement research has focused on the quick, exploratory eye movements called saccades. Children diagnosed with ADHD show saccade accuracy consistent with their peers. They are able to quickly and accurately look to a new target in the environment. When instructed not to look a target (anti-saccades), children with ADHD have a more difficult time NOT looking at the stimulus (1). Reading is a series of quick fixations and saccades that affects reading speed. These saccades improves reading fluency in children(2) . Children with ADHD also show reduced tracking ability which further affects reading fluency (3)  (4).

Near Vision and ADHD

Convergence Insufficiency, an eye movement disorder affecting one’s ability to maintain clear near vision, is found at three times the rate in ADHD children compared to those not diagnosed with ADHD(5).  A study also shows that children with symptomatic convergence insufficiency score higher (more negative behaviors) on an academic behavior scale then those children diagnosed with ADHD (7). So convergence problems can be associated with ADHD-like behavior problems.

ADHD and Optometry

Optometry is aware of the link between eye movements, behavior and academic performance. ADHD symptoms can mimic the behavioral signs of eye movement problems, even when a child is unable to vocalize the vision problems he is has having. Treatment of convergence problems is also known to reduce the symptoms of ADHD reported by parents (6). Treating saccade and tracking problems also helps to improve reading fluency and improve academic performance.

Only a complete evaluation by an optometrist that specializes in eye movement problems can help identify these problems that could be limiting performance in a child with ADHD. Treatment of these problems with in-office vision therapy can help improve a child’s academic performance.

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Assessment and treatment of Saccade Problems

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Saccades – The Quick Movement of the Eyes

Saccades are quick, short movements of the eyes. The cavemen used them to quickly assess the environment and see where a threat (or dinner) might be. We use them now for reading, in a series of quick movements and fixation. We also use saccades to update changes in our environment, so they are influenced by peripheral awareness.  They help build a spatial map of the environment. The movements are involuntary and triggered by changes in the spatial environment.

One can look for inaccurate saccades associated with TBI, concussions and strokes. Inaccurate saccades are also associated with most binocular vision problems, like convergence insufficiency. Poor reading performance can be related to inaccurate saccades as well.

Measuring the Saccade Problem

Saccades testing can show a therapist overshooting or undershooting during the movements, but objective measurement helps set goals. Tools like the Viso-Graph or Right-Eye may be used by the vision therapy doctor to measure these saccade inaccuracies, but these can be pricy solutions often out of reach for the typical therapy clinic or school-based therapist.

The King-Devick, a tool originally developed for field side concussion testing, can also be used for saccade assessment. It now has aged-based norms for their number reading task making it a useful tool for goal-making. It is available as an iPad app at various prices depending on features.

Developmental Eye Movement test

The DEM provides good objective data concerning eye movement accuracy. It correlates well to reading fluency. It is inexpensive and quick to give and score.

The Developmental Eye Movement test (DEM), is a standardized assessment of saccade accuracy. It is standardized for 5-13 year olds, though testing indicates values for a 13 year old are generally valid for an adult. 

The DEM has 4 parts, all involve the timed reading of a list of numbers. The first part is sample of horizontal numbers used to insure the patient can see the text adequately. In the next section, two vertical columns of numbers are read and timed with errors noted.  There are two vertical tests with the times added.

There is the final horizontal test which present horizontal lines of unevenly spaced numbers, which the subject reads while being timed with omissions and substitutions noted.

Times are compared to norms based on age or grade percentiles, They are then used to derive a ratio of horizontal to vertical times that help to identify the cause of the errors, either automatically (subjects ability to call out numbers) versus ocular motor difficulty.

The DEM is not perfect as the person must be verbal and recognize numbers. Frequently the task of reading out loud produces a lot anxiety for children that have problems with the task also. Observation of behaviors during the DEM and the reading can also give some insight.

The tester should note…

  • does the child hold the material very close to his face ?
  • …or far?
  • does he squint or rub his eyes during the assessment?
  • does he use his finger to follow the letters?
  • does he move his head during testing? This is very telling as using head movement rather than eye movement slows fluency and saccade accuracy.
  • are there long pauses at the beginning of a new as the child attempts to find the correct line
  • does accuracy of words get worse as the reading continues or does the child use context to fabricate the end of the sentence?
  • Does he turn his head to the left or right?

What did it look like?

Following reading, ask some specific questions if the child had difficulty to help identify what the child is seeing. These questions sound crazy, but make perfect sense to child with saccade or near vision problems.

  • do the words move when try to read them?
  • do you see double?
  • do they blurry then clear then blurry?
  • do they appear to float?

Sometimes the children have a hard time describing just what they see. Parents are often very surprised at the responses to these questions as the child did not know that they are not seeing well.

Treatment

The treatment for saccade problems, like all ocular motor problems, assumes the child is in best corrected visual acuity.

The Hart Chart Decoding activity is also a good task.  This task has a grid of letters on one sheet and themed (there’s SpongeBob and Sports, and others)secret messages on another. Each letter in the massage corresponds to a column/row combination that the child counts to find the letter. Initially the child is allowed to use his finger to help count the rows and columns, but as they get better at the task, the finger is no longer allowed.

EyeCanLearn.com   is an amazing website with vision games and printable with saccade activities.

Having a child read the first letter of words in a paragraph can improve saccade accuracy as well simple vertical strips of letters that can be more further apart. The therapist can add a metronome to these tasks to help increase the pace.  Add balance to these task to increase the challenge of the brain and visual system.

Saccade strips are two strips of paper with vertical letters. The patient reads the letters left to right and top to bottom. Start with the strips close together then separate them as the the patient gets quicker. Remember to keep the head still, even if the therapist has to help!

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How do we see up close?

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The Near Vision System

“I can’t see the board” is a common reason children come for their first eye exam. But problems seeing close are more closely related to academic success then 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 discomfort 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 to 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) Accommodative Convergence– as an object moves closer, the eyes move nasally 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 the 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 end up wearing bifocals.

Here is a great example of it all working together:

As something moves toward us, the brain adjusts with the right amount of accommodation and convergence, in addition to the pupil constriction. The amount of both convergence and accommodation can be calculated by the the optometrist to come up with the AC/A ratio. This number gives the optometrist clues to the efficiency of the system.

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

 

In some children, both of the lenses tend to over focus making them work very hard to maintain focus of near vision objects. The optometrist can assess this and improve it with glasses also. The child with accommodation problems will be rubbing his eyes during close work. He might complain of headaches when reading. He may show poor comprehension and poor reading skills. Or he may not show any of these signs. He may have a short reading span, or have a difficult time hold still, perhaps mis-identified as ADD.

Without enough convergence, the muscles that focus the lens tire as they work to keep near things in focus. They cause similar problems as poor accommodation and frequently a child will has both. This multi-process system is very flexible in children. Therefore, some children have problems coordinating the system. The condition is called convergence insufficiency and is a common vision problem in children. There will be a separate discussion of CI later.

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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