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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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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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 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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Assessing Eye Movements

Assessing Eye Movements

Assessing eye movements should be a regular part of every therapists evaluation process. We get 75% of the information about our environment from vision and vision affects things like reading, handwriting and balance.

Before starting this evaluation, ask about the patients most recent eye exam. A patient not in best corrected visual acuity may have difficult time fixating and therefore show poor ocular motor skills. Every child needs a compete

Nystagmus

An involuntary movement of the eyes, called a nystagmus.  These are described as a congenital or acquired nystagmus and further described as jerky (faster in one direction than the other) or pendular (same speed in each direction).

Congenital Nystagmus

Assessing Eye Movements

Assessing eye movements is quick and easy and gives the therapist vital information on about the patient may be seeing the world . Its easy to do…just watch!!!

 

 

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