Common Birth to 3 Vision Conditions

Vision Birth to Three

The visual system at birth has a lot of development to do. The early eye exam (6 months to one year) should find anything that may impede this development.

Common Birth to 3 vision problems

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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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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“When should we see no head movement during visual tracking?”

When should they hold their head still…

The development  of the visual system in children is much discussed. The AOA offers time lines which have development of eye movement continuing to improve at 36 months. This development is dependent upon many factors including the development of the brain as whole and the vestibular, and proprioceptive systems. The development of these systems is inter-dependent. Problems in the visual system will affect development of the vestibular and other systems and impact the developmental movement sequence. This is why the first eye exam is recommended at 6 months of age.

In the birth to 3 three year old, developmental delays would most likely include tracking and saccades problems, particularly when neurological problems (seizures, anoxia, CP, etc) are present. As therapists, our treatments should should stimulate as many sensory systems at possible, including vision.

Eye Movement norms

The best information on the development of eye movement accuracy comes from the NSUCO Ocular motor norms. The NSUCO protocol looks at ability to perform the movement, accuracy of the movement, amount of head movement present and the amount of body movement present during the testing of tracking and saccades. Each of these skills is rated 1-5 with each score defined in the above referenced article. This is the standard way saccades and tracking are quantified by ODs. Each movement would include 4 numbers describing the child ability to perform the movement. This is a somewhat subjective test, much as our manual muscle testing is somewhat subjective. It is most important for the therapist to recognize the errors and refer to the doctor for scoring, then be able to interpret the score as provided by the doctor.

The norms begin at age 5 and support the idea of a constantly improving ocular motor system until full maturity at the age of the 10. The paper further references minimal standards from age 5 to 10 to help identify less than age appropriate eye movement accuracy.

The Therapist’s job

We should be screening these eye movement on all of our patients. Children with developmental delays have a high incidence of ocular motor problems which affect balance, reading, spatial awareness, fine motor and visual motor integration development. These ocular motor problems are influencing the outcomes of our interventions so being testing them should be a part of every OT and PTs evaluation process.

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Worth 4 Dot

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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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 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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Assessing Eye Movements

Assessing Eye Movements

As therapists, we should assess EOM or extra ocular movements, the optometry term for eye range of motion. Looking at these movements can give information about brain and cranial nerve function as well as help identify limitations on functional tasks like reading .

Eye movements use similar names as other movements with inferior being downward, superior being upward, lateral movements described as duction with adduction  moving toward the nose (nasal)and abduction away from the nose (temporal). Optometry also has vergence, which is the movement of both eyes toward the nose (convergence) or away from the nose (divergence). Smooth convergence and divergence is important in the near focusing system.

With the patient seated and focused on a point about 40 cm away, the eyes should be still. This is called fixation.  A small rhythmic movement, called nystagmus, is a sign of a central nervous system problem. It is often associated central nervous system problems like Multiple Sclerosis.  It is a frequent early sign of the disorder. It is also closely linked to the vestibular system and the patient might report dizziness. When congenital, the brain adjusts to movements as in the video below.

Congenital Nystagmus

9 points of primary gaze are assessed having the patient follow a point to left/right/up/down/up left/low left/upright/low right. The eyes should move together through all of these points.

9points of gaze_normal_540

Assessing Cardinal Gaze

Each of these movements is control by cranial nerves and failure of an orbit to move in a direction could be a sign of cranial nerve problem or a muscle problem. This occurs frequently as a result of brain injury or trauma to the eye or orbit. This can also be congenital. This eye turn is referred to as a strabismus.  Strabismus causes diplopia or double vision. They can be improved with prism by an optometrist or possible surgery to shorten or lengthen the muscle by an ophthalmologist.

To assess convergence use the near point convergence test. In this assessment, a target held about 1 meter from the patient’s nose and slowly brought toward the nose. The patient is instructed to tell the tester when they see two of the targets. The target should get to within 6cm to be considered “normal”. The test should be done 5 times with the final result be the distance at which the child saw double on this final trial. Reduced convergence is not uncommon following brain injury and stroke and is linked to reading difficulty in children. Reduced convergence makes near vision tasks more difficult as the brain has work harder to see clear. This is called convergence insufficiency. The condition even has its own  website.  This has also become more common in adults we put demands on our near vision system with increased use of smart phones.

Near Point Convergence test

In tracking, the patient follows a target in a circular pattern, both clockwise and counter-clockwise making 2 revolutions each direction. Tester notes the number of fixation loses, the smoothness of the movements and the ability of the eyes to move together.

Eye Pursuits or Tracking

Saccades are very quick eye movements of very short duration. It is a series of fixations and saccades that allows one to read efficiently. Inaccurate saccades are frequently associated with poor reading skills. Optometry can improve saccade accuracy and improve reading .  Saccades testing has the patient fixate from one point to another with the tester noting adjustments following the fixation and if the eyes move together. We can perform the Developmental Test of Eye Movement  or the King-Devick for objective testing of eye movement.  Saccade accuracy can be an indicator for possible concussion as well.

Saccade testing

Abnormal EOM tests should be referred to optometry for complete assessment. They are often related to central nervous system problems, cranial nerve palsy’s or cerebellar problems. They are common in stroke and brain injury survivors and cause decreased reading ability, balance and depth perception.  Patients frequently suffer with eye movement problems for years following a stroke or brain injury, but with the right tools, they can be improved improving a patient’s functional ability.

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