Common Birth to 3 Vision Conditions

Vision Birth to Three

The visual system at birth is very immature. After all, our new born has been a a dark environment since conception! Acuity develops over time as does the accuracy of eye movements.

Age (months) Skill
1 to 4 acuity is 20/200 to 20/400, follow slow moving object intermittently, basic eye movements present
5 to 8 developing color vision, not as good as adult yet
9 to 12 improving acuity, responds to faces
12 to 24 acuity improved to 20/50, developing eye-hand coordination, depth perception
24 to 36 acuity is 20/20, begins exploring environment
36 to 48 using vision for fine motor coordination.  At 48 months, refined eye movements with decreased head movement.

Assessment of eye movements before the age of three should focus on full range of motion understanding that the accuracy of these movements are still developing and will demonstrate poor accuracy and excess head movement.

“When should their head be still??”

This separation of head and eye movements should begin at about 4 years old with no head movement observed during assessment at age 10 and tapering in between. This going to be tied to development of the proprioceptive and vestibular system  as well as development of the overall brain. These system are closely linked and delay in any of them will cause a delay in ocular motor skill development as well.

When should a baby get their first eye exam?

The first eye exam should be at 6-12 months old. Infantsee, a public health program developed by the American Optometry Association, provides this first eye exam at no charge. It is vital to detect any problem that could limit development of the visual system. The next eye exam at 3 years, then annually from ages 6-18. Just as the child is growing a changing during these years, their vision could be changing as well. With the visual demands placed on our children during these years, an annual exam makes sure they are ready to meet those demands.

Common Birth to 3 vision problems

The below table is just a few the pathologies that could limit development of the visual system.

Common Birth to 3 Eye problems Pathology Acuity Prognosis Functional Problems Modification
Coloboma failure of the halves of the eye to join completely inutreo, may affect pupil, retina or lid varies depending of retinal damage stable condition glare problems if pupil is affected and retina is functional, reduced bincular depth percpetion sunglasses, motor practice
Optic Nerve Hypoplasia decreased evelopment of the optic nerve, usually assocaied with midbrain/endocrine problems varies from minimal affect to near blindness, possbile field cut, possble nystagmus stable condition Delayed motor development due to reduced visual input.   Refer to TVI at 3 yrs old. vestibular and motor facilitation tasks.
Retinopathy of Pre-Maturity scarring related to excessive blood vessel growth during prolonged O2 exposure in premature infants varies by amount of scarring stable condition depends on level of scarring, may be no delays related to vision based on acuity
Corticol Visual Impairment lack of vision due to visual pathway damage/failure to develop Usually not 100% blind stable condition near blindness, refer to TVI, use contrasting colors, movment and work peripheral to central to investigate amount of vision. Referal to TVI is important for school readiness.
Accommodative Esotropia medial eye turn due to extreme farsightedness 20/20 with glasses in place, eye turn also corrects with glasses improves, but child will remain in glasses throughout life none with early correction, amblypoia without correction glasses should be comfortable and worn at all times.
Infantile Esotropia medial eye turn not related to generally reduced due to amblyopia, may improve with correction varies, tx by surgery vs VT vs Botox reduced motor development per doctors order concerning patching, facillitate motor improvement
Amblyopia reduced acuity due decreased visual pathway development  due to prolonged suppression or lack of stimulation to visual pathway varies, 20/200 or worse to 20/50 depending on patching complaince and glasses wear compliance. may improve with compliance of tx and glasses wear, binocular vision therapy reduced motor dev., head turns, decrease binocular depth perception. Brain with compensate in time motor dev facilitation, exercise amblyopic eye if currently patching, binocular vision activities
Strabismus eye mis-alignment at rest, corrected with surgery vs VT vs Botox varies, generally reduced due to amblyopia varies greatly. Long term, brain adapts to suppression of the turned eye reduced motor dev, self-esteem, self conscious of turned eye, reduced binocular depth perception eye exercises per doctors order, facilitate motor development

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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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(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

 

 

Letter Reversals

Letter Reversals

Letter reversals are frequently an area of concern for parents as their child begins to learn writing and reading. Reversals are often viewed as a sign of dyslexia and are surrounded by myth. Here are the facts on letter reversals

  • Letter reversals are common and appropriate until a child reaches 7 or 8 years old (second grade).
  • After the age of 7-8, the children who continue to have reversals are the children that are having difficulty with reading(1)
  • Learning letters is the first time a child learns that an item becomes a different thing based on the way it is facing. A cup from seen from one side or the other is still a cup but a “b” seen the other way (“d”) is not the same thing.
  • Visual spatial and left/right body awareness correlated with children having letter reversal problems suggesting that addressing left/right awareness would improve letter reversals (2)
  • Working memory deficits, also found in dyslexia, were found in children with letter reversals, so addressing working memory may improve letter reversals. (3)
  • Children with ADHD tend to have more reversals, possibly related to difficulty in an inability to to suppress the more natural left-right flow of making most letters.

Treatment Ideas

Having the child the pull letters from a bag and identify the letters without looking at them has been a great activity (suggested by Dr. Charles Boulet) and correlated well with children having difficulty with this task that have reversal problems.

Dr. Kenneth Lane OD, FCOVD’s book , Developing Ocular Motor and Visual Perceptual Skills: An Activity Workbook, has an excellent discussion of letter reversals as well as treatment techniques. Presenting p-q-d-b chart and having the child touch “p” and “b”  with right and q and d with the left has proven to be very challenging. This activity include a component of eye0hand cooridnation and saccade accuracy that will further improve binocular vision and saccade accuracy.

The Optomteric Extension Program offers Recognition of Reversals Workbook, also by Dr, Lane (a great bookstore!!). This workbook has more activities for reversals and its only $20.

Calm the panic!!

In a few cases, letter reversals after the age of 7-8 can indicate dyslexia, but there are many other reasons a child may have reversals.

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References

  1. Terepocki, M., Kruk, R. S., & Willows, D. M. (n.d.). The incidence and nature of letter orientation errors in reading disability. Retrieved October 04, 2017, from https://www.ncbi.nlm.nih.gov/pubmed/15493319
  2. McMonnies, C. W. (1992, October). Visuo-spatial discrimination and mirror image letter reversals in reading. Retrieved October 04, 2017, from https://www.ncbi.nlm.nih.gov/pubmed/1430744
  3. Brooks, A. D., Berninger, V. W., & Abbott, R. D. (n.d.). Letter naming and letter writing reversals in children with dyslexia: momentary inefficiency in the phonological and orthographic loops of working memory. Retrieved October 04, 2017, from https://www.ncbi.nlm.nih.gov/pubmed/21978009
  4. Levy, F., & Young, D. (n.d.). Letter Reversals, Default Mode, and Childhood ADHD. Retrieved October 04, 2017, from https://www.ncbi.nlm.nih.gov/pubmed/26794673

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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“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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Motion sickness and the eyes

Motion Sickness

As part of my vision rehab evaluation with patient I always ask about motion sensitivity (or car sickness). The answer can give cues to the functioning of the ambient (magnocellular)visual system.

What is motion sickness?

The semicircular canals within the ears (vestibular system) tell the body that it is motion. The magnocellular visual pathway also “confirms” this motion as movement is observed. But when the system is less aware of magnocellular output (such when one is reading or playing a game in the car) then the vestibular and the magnocellular system get different information. When this happens nausea and rest follow.

The magnocellular system

The magnocellular system is responsible for visual input that affects gait, posture and balance. It also helps us track during reading as it gives the brain the ability to see the line peripherally as the eyes focus on the words being read. There was some discussion that magnocellular problems were associated with dyslexia as well.

Treating the Magnocellular system

To improve magnocellular input, we do activities on a balance board while performing visual scanning tasks that emphasize keeping the head still and maintaining balance as targets are toughed. I will have patient do this while wearing glasses with binasal occlusion or base up or down prism depending on posture. This can also be helpful with idiopathic toe walking.

More recently, motion coherence tests have been developed which help to quantify magnocellular function. In these computer based tests, dot move randomly and the patient must decide which direction most of the dots are moving. Devices like the Neuro-tracker also work on magnocellular function.

Using the system as tool

The magnocellular system can be a powerful tool in improving posture and balance. The altered visual input quickly re-aligns posture without cueing and makes use of the brain natural ability.

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The Brock String

The Brock String

The humble Brock consists of a length of string (from 3 to 10 ft) with a series of beads (from 3 to 5 beads) placed at various intervals. This simple instrument is powerful tools in teaching binocular vision skills.  While the configurations vary, it is elegantly simple and effective in teaching the brain how to make the eyes convergence.

How the use a Brock string

The 3 ft string is generally sufficient unless working with an athlete then a longer string my be needed. Four or five beads make for enough targets to be useful.

  1. With the beads evenly spaced (closest bead at about 2cm, furthest about 40 cm), have the patient hold one end of brock string to their nose.
  2. The therapist holds the string tight and angled slightly downward.
  3. Have the patient fixate on one of the further beads to begin. The patient should see one bead (indicating focus to a single point) and two strings meeting at the front of the bead (indicating both eyes are working together. It should look like the picture below.
  4.  Have the patient alternate from bead to bead, working closer and back to exercise the convergence muscles. Look for difficulty with maintaining the fixation as the muscle fatigue.

Brock-String-4-300x65

Here is video of a brock string in action. Notice the the “bobbles” as she moves from bead to bead. This is an indication of weakness. When they see it correctly, the eyes get very still.

Why does this work?

The brock string takes advantage of “physiologic diplopia”. The eyes can only focus clearly on single point with all other things within the viewing area seen as double. This is a normal way for our eyes to work. The brock string uses this physiologic diplopia as a cue to the let brain know the eyes are working together correctly.

Remember, before the brock string, check for full extra ocular movements and exercise the eyes separately.

Brock strings are easy to make and make a great home program addition.

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