“Ontogeny” – The Predictable Development of an Individual
Many parents are often amazed when they first learn that there is more to vision than just seeing clearly and that there are clear developmental patterns that the visual systems take in a normally developing person, which can be disrupted and affect behavior, performance and overall growth and success of that person.
They eyes are really (embryologically speaking) an outward extension of the brain, or what Dr. Sanet, FCOVD calls the “movable brain” to capture light information and send it further back into the visual systems to be processed for meaning in order to direct action. The eyes are just one part of the sensorimotor set of systems of vision that must learn how to operate through experience. If it develops successfully, vision will become the dominant sense and will use 65% of the brain pathways (compared to the other 1/3rd of the pathways used for all the other senses combined).
To gain a better understanding of how this works, let’s start with the basic building blocks of sensorimotor development – primitive reflexes. Primitive reflexes are also called survival reflexes. They originate in the brainstem, which is the first part of the brain to develop, and protects the fetus in utero, helps guide them through the birth canal, and helps the newborn learn and develop.
Primitive reflexes are involuntary movements that an infant makes in response to a stimulus, like light, touch, or sound, and account for most of the movement patterns an infant experiences during the first few months of life. Pediatricians and some obstetricians look for these reflexes as a “system’s check” to confirm if a newborn’s brainstem is functioning normally. As each reflex fulfills its function and the higher cortical brain (the thinking part of the brain) integrates them, postural reflexes, which are more advanced balance and movement patterns, will emerge. The integration of primitive reflex sets the stage for all future behavior, movement and learning. Disruption in this process will negatively affect normal sensory and motor development because the brainstem interferes with cortical processing and cerebellum development.
Read more on Primitive Reflexes by looking up research and books by Sally Goddard, Peter Blythe, Brendan O’Hara, Philip Teitelbaum, Al Sutton and Patricia Lemer.
So, What Does Primitive Reflexes Have to do with Vision?
This section paraphrases the works of Dr. Carol Marusich, FCOVD and Dr. Al Sutton, FCOVD. Vision development of a child can be seen in ontogenic patterns (specific developmental patterns) and is integrated with the development of the whole child’s action system, including posture, coordination, personality and intelligence.
The eyes themselves begin developing in a human embryo at 18 days old. The eye is an instrument of vision, but not where vision actually occurs. After birth, there is correlation between the development of the foveal acuity and neurological development. This means that the brain learns to see and thereby develops the structures it needs to do so.
Vision is a product of the functions of the other neurological systems interacting with the eye when the neural pathways are formed between the eyes, the brain and the body in the prenatal and early years of life.
Remember, primitive reflexes are automatic movements directed from the brainstem and executed without cortical involvement (the higher thinking parts of the brain). That means that these movement patterns happen without your control. They are necessary for survival in an infant, but also create important learning experiences. These experiences become foundations for future neuromuscular (sensorimotor) development. They also help facilitate the “mapping” or organization of neurological information in the brain to ultimately help us build a visual spatial world.
Primitive reflexes provide mechanisms to help the infant understand what he sees and help him learn to coordinate his ocular systems to build higher level visual skills (focusing, fusion, fixation, eye teaming).
If primitive reflexes remain very active beyond 1 year of age, it can interfere with the development of higher levels visual skills and/or prevent postural reflexes from emerging.
An article published this year in the Optometry and Vision Development Journal found that saccadic accuracy (the quick eye movements used in reading to jump to the next chuck of words and to jump to the next line) and impaired reading ability was associated with retained primitive reflexes, especially the Tonic Labrynthine Reflex (TLR) and the Symmetric Tonic Neck Reflex (STNR).
If interested in the article, here is the article to reference:
Gonzales SR, Ciuffreda K, Hernandez LC, Escalante JB. The correlation between primitive reflexes and saccadic eye movements in 5th grade children with teacher-reported reading problems. Opt Vis Dev 2008: 39(3):140.
Moro and TLR
The Moro and Tonic Labyrinthine Reflex (TLR) are vestibular (inner ear) in origin and are activated by changes of position in space (stimulation of labyrinths of the inner ear).
The Moro reflex provides an immediate, involuntary “alarm” system. It’s your fight/flight response. It should integrate at about 4 months old. If it is retained, sensitivity to changes in sound, light, touch, taste, temperature, movement, smell, flicker of light and short wavelengths of light (blues). It can affect endocrine and biochemical balances as well.
The TLR helps the baby “straighten out” after birth. Starts to integrate at 4 mo old but it’s very gradual and can be seen up to 3 years of age. It begins to phase out so that the infant can develop antigravity control of the head…which leads to balance, muscle tone and proprioception. Without developing a secure reference point in space, you’ll have difficulty judging space, distance, direction and velocity. Sense of direction is based on the knowledge of “where am I” in space and time (orientation). If antigravity control of head and posture is limited, oculomotor functioning will be impaired because the eyes operate from the same circuit in the brain. Balance will be affected by poor visual processing and vision will be affected by poor balance. Very common to have troubles with reversals, convergence and binocular vision when the TLR does not integrate at the proper time.
ATNR
The Asymmetrical Tonic Neck Reflex (ATNR) integrates by 6 months. It assists in the birthing process and helps to develop muscle tone, kicking and stimulates vestibular function in utero. It is one reason why C-Section babies are at higher risk for developmental delay. The ATNR provides the first eye-hand coordination that pushes vision out to arm’s length and brings the awareness of distance. It leads to crawling with a fluent cross pattern movement. When the ATNR does not integrate at the proper time, it can become a major obstacle in establishing a preferred hand, leg, eye or ear and crossing the midline in visual tracking. Balance, cross-pattern movements, handwriting, VMI, visual perception, pursuits and laterality can be affected.
STNR
The Symmetrical Tonic Neck Reflex (STNR) integrates by 11 months and tends to emerge when the ATNR phases out and will help inhibit the TLR. It enables you to defy gravity for the first time and raise the body off the floor to begin creeping (hands and knees). The STNR automatically cause the eyes to alternately fixate at far and near, expanding vision development from arms length to far away. It completes the first eye training sequence. 
If it is not integrated in at the proper time, you can have difficulties copying, poor posture, poor hand-eye coordination, and difficulties adjusting binocular vision and accomodation. Those that don’t creep tend to have a hard time with near point vision.
Spinal Galant
The Spinal Galant (SG) integrates by 9 months. There is still not a clear understanding of the purpose of the SG, but it is thought to also help the baby through the birth canal and may help to develop response to sound in utero. If it does not integrate well, the most common manifestation of the SG is the “ants in the pants” syndrome where a child cannot sit still or sit in a chair. They often have difficulty with tags or particular types of clothing (too loose or too tight). It can manifest on one side or both sides of the body. If both SGs of the body are stimulated at the same time, it can cause bedwetting. Integrating the SG can help “calm” a child and help them to sit still and concentrate.
Common causes of retained reflexes are cesarean section, not enough tummy time, lack of or little experience creeping and crawling, early walkers, head injury, excessive falls, and chronic ear infections.
Integrating Primitive Reflexes
Primitive reflexes can be integrated back into the system to help develop a solid sensory-motor foundation. A good sensory-integration occupational therapist can help provide this type of therapy. A growing number of Behavioral Optometrists, such as myself, also provide this type of therapy in conjunction with other aspects of vision therapy because it affects vision so profoundly. When primitive reflexes are integrated, it makes vision therapy that much more successful because the patient is able to build from a better starting point, so to speak. If a child is very “reflex” bound and gross and fine motor control is very impacted, Behavioral Optometrists and Occupational Therapists can co-manage patients very effectively and more efficiently than if they were to work with them on their own.
Check back in the weeks to come. My plan is to also give you some screening devices to see if you or someone you know is at risk for having retained reflexes and simple exercises that you can do at home to help aid in integrating them.
