Retained Primitive Reflexes
Retained Primitive Reflexes
Many people who have cared for an infant are familiar with primitive reflexes: Turn an infant’s head to one side and both arms turn to that side (Asymmetric Tonic Neck Reflex). Stroke an infant’s lower back on one side and their side muscles instantly contract (Spinal Galant Reflex). Surprised by a sound, the infant instantly spreads their hands wide, throws their head back, and opens their eyes widely (Moro Reflex). Doctors often gauge the development of the child by the orderly progression of these reflexes.
Under optimal circumstances, all reflexes “initiate” during the appropriate stage of the child’s development, “integrate” themselves as a fully functioning reflex, and then “inhibit” or fall away when it’s time to move on to the next developmental stage. It is vital that this occurs. If various reflexes fail to initiate, integrate and inhibit, the system is locked into a developmental holding pattern that prevents natural maturation of neural systems, inevitably leading to mild through severe learning and performance challenges.
Symptoms of the Primitive Reflexes that relate to Behavioral Optometry
- Vestibular problems: motion sickness, poor balance and coordination.
- Physical timidity.
- Eye movement and visual perceptual problems.
- Stimulus bound effect – eyes are drawn to the perimeter of a shape whereas details are ignored.
- Light sensitivity, difficulty with black print on white paper, tires easily under fluorescent lighting.
- Possible auditory confusion resulting from hypersensitivity to specific sounds (the child may have poor auditory discrimination skills and have difficulty shutting out background noise).
- Allergies and lowered immunity; i.e. asthma, eczema, or a history of frequent ear, nose, and throat infections.
- Adverse reaction to drugs.
- Poor stamina.
- Dislike of change or surprise; poor adaptability.
- Poor posture and/or stooping.
- Hypotonus (weak muscle tone).
- Vestibular-related problems (i.e. poor sense of balance, carsickness).
- Dislike of sporting activities, physical education classes, running, etc.
- Eye movement, visual perceptual, and spatial problems.
- Poor sequencing skills.
- Poor sense of time.
- Poor organization skills.
- Poor concentration.
- Poor short-term memory.
- Hip rotation to one side when walking.
- Poor concentration.
- Poor short-term memory.
- Hip rotation to one side when walking.
- Balance may be affected as a result of head movements to either side.
- Homolateral instead of normal cross-pattern movements (i.e. when walking, marching, skipping)
- Difficulty crossing the midline.
- Poor ocular “pursuit” movements, especially at the midline.
- Mixed laterality (child may use left foot, right hand, left ear, or he/she may use left or right hand interchangeably for the same task).
- Poor handwriting and poor expression of ideas on paper.
- Visual-perceptual problems, particularly in symmetrical representation of figures.
- Poor posture.
- The tendency to slump when sitting, particularly at a desk or table.
- Simian (ape-like) walk.
- Poor eye-hand coordination, messy eater, clumsy child syndrome.
- Difficulties with readjustment of binocular vision (child cannot change focus easily from blackboard to desk).
- The slowness at copying tasks.
- Poor swimming skills.
Eye movements require the highest level of movement precision. These skills allow rapid and accurate shifting of the eyes along the lines of print in a book, from the desk to the chalkboard, and from the computer to the keyboard to the text. Inadequate eye movement control may cause problems such as losing one’s place when reading, having difficulty copying from the chalkboard to the desk or from the text to the computer, skipping or omitting small words when reading, or impaired ability to judge distances accurately or recognize objects quickly.
Tracking and locating skills are measured by asking the patient to follow a shiny 1cm ball with the eyes. The patient should be able to track the ball over the full range of possible eye movements with smooth, developmentally appropriate eye movements that are independent of the body. Whenever there is a moderate amount of supporting head movement involved in tracking moving objects, one is not as accurate and must use an abnormally large amount of effort to perform the task. We first develop the ability to track along the horizontal meridian, then vertical, then diagonal, and lastly along a circular plane.
This test times how long a child takes to rapidly call out a series of numbers in a horizontal array.
In this test, the patient follows a line with the eyes from a starting point to a finishing point. The time to complete the task and the accuracy of the trace is measured.
Binocular Integration (Eye Teaming Ability)
The human visual system is designed so that the paired eyes and all their reciprocating muscles can work to such a high degree of teaming that the two eyes perform as one. This skill is intimately related to eye movement control and focusing ability. Deficiencies in eye teaming can cause not only strabismus (turned eye), suppression (blocking out the vision of one eye) or diplopia (double vision), but also such problems as shortened attention span, the use of excess effort when processing visual information, and improper distance judgements on the road or when playing sports.
Stereopsis (depth perception) is a function of proper binocular fusion. It allows a critical judgment of the relative distance between two objects.
The cover tests reveals whether the eyes are aligned or not.
This is a test to see if the eyes are able to align to a near target, then diverge to a more distant target with symmetry.
This test evaluates how far the eyes can converge and diverge while maintaining clear, single vision.
This test evaluates where the eyes converge to while reading.
Additional Visual Information Acquisition Skills
1- Ishihara color vision test
2- Readalyzer visual function tests and relative reading efficiency tests
The patient is given a paragraph to read silently while wearing goggles. The microelectronics inside the goggles allow for extremely accurate high-speed recordings of the exact positions of the eye movements during the reading of the passage. The data are captured to a computer and analyzed automatically. Poor readers generally have shorter saccades (movements), many more fixations per line, a higher frequency of regressions (backward movements), and low reading speed. In other words, many people are poor readers because they have never learned the proper eye movement skills used in reading. Some children may be quite intelligent, yet because the reading process is so tiring and frustrating, they will give up trying to read. These children often become discipline problems in the classroom and at home.
- Comprehension Test
There is a comprehension test for the passage read consisting of ten “yes” or “no” questions. Since 50% would be the score expected if the questions were simply guessed at, we required at least 70% to indicate that the student understands the passage.
- Regressions/100 Words
Regressions refer to backward movements of the eyes in the middle of reading a line, usually to reread a word or a part of a word. The normal return sweep of the eyes to the beginning of the next line is not included in the count of regressions.
- Fixation Duration
An important factor in overall reading performance is the average duration of fixation. This is the amount of time the eyes stay stopped while the brain figures out what is being seen.
- Reading Rate
This is the rate in words per minute attained by combining all of the above factors. Keep in mind that the school grade levels referred to indicate eye movement development, not school reading levels. If someone scores at Grade 4, it means their eye movements during reading are equal to that of the average fourth grade reader. If they have not done much reading and have not developed their vocabulary, they may be actually reading far below what is considered a fourth grade reading level.
3- Oral Reading
Visualization / Visual Memory
These skills involve the ability to form a mental image in the “mind’s eye”, to change that image at will or when directed, and to project images and formulate ideas, for imagination and creativity. These skills are important for learning letters and sight words, and for developing rich reading comprehension abilities. Visual memory also involves the ability to visually “see” things spoken, felt or remembered so that vision substitutes or complements experiences for greater understanding.
This is a test measuring visual memory by drawing symbols from memory after looking at them for 10 seconds.
A shape on a transparency is shown. The patient is asked to match it to 4 variations of that shape on a reference card. He / she is then asked to match the shape if viewing it from behind, if it was flipped vertically, and if it was flipped vertically and viewed from behind.
In this activity, five objects are shown. The patient is to look at them for ten seconds; then, they are covered up. While looking at them, the verbal center is occupied by reciting the alphabet. The patient is to refer back to the image of the objects and recite their location. Following this, one object is moved and the patient is asked to report the relative locations.
In this activity, the patient is asked to look at the size of his/her shoe and estimate how many “shoe-lengths” it would take to get from the current position to the end of the room. He/she is also asked how long it would take to travel the distance.
In this activity, I read out a description of an image – the patient is to visualize the image, then reproduce it on paper.
A line is drawn with the number zero at the beginning and the number ten at the end. Various numbers within that array are called out and the patient is to try to draw them in the appropriate position.
The Binocular Continuum
An efficient, well-developed binocular vision system encompasses many skills and allows the person to explore the world and direct action within it. Demands on our visual system may be central (right in front of us), peripheral (off to the side), or a combination of each. Likewise, some demands are static (not moving) whereas others are dynamic (moving). The following lists the main skills required for an efficient, well-developed binocular vision system and the tests used to evaluate these skills.
First of all, we need each eye to be able to fixate with the fovea, we need the light to focus at the position of the fovea, and we need to be able to adjust our focus when looking at objects of varying distances.
The Snellen fractions 20/20, 30/30, etc. are measures of sharpness of sight. They relate to the ability to identify a letter of a certain size at a specified distance. Deficiencies in visual acuity may cause blurred sight at distance or near, and squinting to see clearly. Acuities give no information as to whether or not meaning is obtained from visual input, how much effort is needed to see clearly or singly or whether or not vision is single, suppressed, or less efficient when using both eyes as opposed to using each eye individually.
This is a test to detect eccentric fixation, a condition that occurs when a non-foveal point is being used for fixation. The patient fixates on a point on a purple coloured gel filter which fits over a light source with a rotating polarizing filter. Since the macula contains fibres that polarize light, an effect called “Hadinger’s Brush” is seen in the space coincident with the macula. If the Hadinger’s Brush is seen at the point of fixation, the patient has normal fixation.
An important part of any vision evaluation is the determination of the refractive status or optics of the eye. This refers to whether the child is nearsighted (myopic), farsighted (hyperopic), or astigmatic. When a significant degree of refractive error is present, we often prescribe eyeglasses to manage these problems. The refractive status is influenced by overall vision development, individual adaptation to environmental stress, and hereditary factors. If not compensated properly, refractive status can make it more difficult to see clearly and focus without stress at distance or near.
- Objective and subjective refraction, far and near
Rapid, automatic focus adjustment, called accommodation is essential for shifting and sustaining focus. Focusing problems are often associated with difficulties working from the chalkboard and headaches when on the computer or reading. As well, focusing problems can cause image blurring or slower schoolwork performance.
1- Amplitude: This a measure of the full range of focus.
2- Relative Accommodation: This is the amount a person can focus when stimulated with a minus lens and relax with a plus lens.
3- Accommodative Facility: This is the ability to shift focus from distance to near and back.
4- Lag / Lead Of Accommodation: This is how much the focus lags or leads the object of regard. In other words, when the patient is looking at reading material, a lag would be if the eyes are focusing behind the object of regard whereas a lead would be if the eyes are focusing in front.
Binocular Skills – Static, Central
An anaglyph is a stereoscopic image created using two colored images, one red, the other green, viewed with red-green glasses. The Keystone Basic Binocular (KBB) is a group of 13 anaglyphic tests to determine the presence of first (simultaneous perception), second (overlapping images), and third-degree fusion (stereopsis). In addition, it identifies anomalous projection, the condition that occurs in some strabismics when the image seen by a foveal point in one eye is seen by a non-foveal point in the fellow eye. Additionally, the KBB tests for the retinal rivalry (the condition that exists when the brain alternately attends to the image from one eye, then the other), vertical deviation, and fusional reserves.
The cover tests reveals whether the eyes are aligned or not.
1- LCD Anaglyph (Distance): On a distant LCD screen, there are two horizontal bars and two vertical bars – a red and blue of each. The patient wears analglyphic glasses (red-blue). Prisms are used to neutralize the position of these bars.
2- 3D Projector (Distance): This test uses a 3D Projector and NIVIDIA alternating LCD glasses to create an image for each eye. The patient is instructed to adjust the controller to line up the target seen with one eye with the target seen with the other eye.
3- Saladin Card (Near): The Saladin Card has several images, each containing two horizontal lines of varying height – polaroid glasses are worn so one half of the image is seen with the right eye, the other half is seen with the left eye. The patient reports which pair of lines is seen as a continuous horizontal line. The test is repeated for the images with vertical lines as well.
Aniseikonia is the condition that results when there is a significant difference in the perceived size of the images received by the eyes. Using a 3D Projector and NIVIDIA alternating LCD glasses, the patient is asked whether the image presented to the right eye is the same as the image presented to the left eye.
This is the condition that results when the eyes are not rotationally symmetric, resulting in the inability to fuse images. Using a 3D Projector and NIVIDIA alternating LCD glasses, the patient is asked whether the line running through the images is rotated or not.
1- Random Dot Stereogram: This is a near test of stereopsis using random dot patterns – polarized glasses are required to see the stereoscopic images.
2- Lang Stereotest: This is a near test of gross stereopsis – polarized glasses are not required to see the stereoscopic images.
Phoropter: This test evaluates how far the eyes can converge and diverge while maintaining clear, single vision at distance and near.
3D Projector – Smooth Vergences: This test uses a 3D Projector and NIVIDIA alternating LCD glasses to create 3D images which are manipulated to evaluate how far the eyes can converge and diverge while maintaining clear, single vision at a distance.
3D Projector – Jump Ductions: This tests the patient’s ability to change from one level of vergence to another, with a large interval between the two.
These are glasses with striations at 135 degrees in one eye and 045 degrees in the other. When a penlight is shone into one eye, the light forms a streak 090 degrees to the striation. In a visual system where the image from the fovea of the right eye corresponds with the image from the fovea of the left eye, the patient sees two streaks of light, one at 045 degrees, the other at 135, intersecting together at the penlight.
Anaglyphic: In this test, anaglyphic (red-green) glasses are worn while looking at a light source with one white, two red, and one green light. He/she is then asked how many “dots” are seen. A person with well developed binocular vision skills will see luster on the top light, two reds horizontally, and one green on the lower light.
3D Projector: The premise of this test is the same, but it is performed at a distance with a 3D Projector and NIVIDIA alternating LCD glasses.
Binocular Skills – Static, Peripheral
Larger, more peripheral targets are more easily fused by the brain than smaller, more centrally located targets. In this test, a Vectographic Quoit (rope-like image with one image seen by one eye, one image seen by the other) is projected onto a polarizing screen. A patient with a normally functioning visual system will see the Quoit at one half his/her distance from the screen. He/she will also be able to appreciate changes in image size when the disparity (horizontal distance between the images) is increased and decreased.
Luster is the condition that arises when a light source is viewed binocularly through anaglyphic (red-green) glasses. It is a mixture of green and red light, which appears as an off-yellow.