Relationship Between Primitive Reflex and Eye

Deepika K, B.Optom

Fellowship in Clinical Optometry, Aravind Eye Care System, Chennai, India

 

Primitive reflexes are involuntary motor responses originating in the brainstem, present after birth in early child development, that facilitate survival. ⁽¹⁾ These reflexes should be integrated as the child’s motor development matures. ⁽²⁾ A child’s developmental milestones will begin to integrate in the infancy stage and will be dependent on main visual skills like binocular vision, ocular movements and accommodation are necessary for observing, learning, and imitating. ⁽³⁾

Some of the main primitive reflexes that related to eye are:

• Moro reflex
• Tonic labyrinthine reflex (TLR)
• Symmetric tonic neck reflex (STNR)
• Asymmetric tonic neck reflex (ATNR)
• Vestibulo-ocular reflex

Moro Reflex

The earliest primitive reflex is the Moro reflex, this affects motor, ocular, vestibular, and visual perceptual skills.⁽⁴⁾

If the reflex is not integrated, then symptoms are :

• Difficulty with black print on white paper
• Auditory and visual hypersensitivity
• Difficulty ignoring irrelevant visual material ⁽⁵⁾

Figure 1: Moro reflex
[Image courtesy – https://www.teacherspayteachers.com/Product/Moro-Reflex-PDF-Poster-5882160]

Tonic Labyrinthine Reflex (TLR)

TLR affects muscle tone, balance, ocular motor, balance, and auditory discrimination.⁽⁴⁾

• Poor coordination
• Poor sequencing skills
• Toe walking

Symmetrical Tonic Neck Reflex (STNR)

STNR affects crossing midline, focusing from objects near to far, and fixation.⁽⁴⁾

• Messy eater, clumsy child syndrome.
• Poor balance and depth perception

Figure 2:  Symmetrical Tonic Neck Reflex
[Image courtesy – https://www.teacherspayteachers.com/Product/Symmetrical-Tonic-Neck-Reflex-STNR-PDF-Poster-5882134]

Vestibulo-Ocular reflex :

The vestibular-ocular reflex ( VOR), which is most common to vertebrates, helps us to keep our eyes focused on a fixed point even while our heads are moving. ⁽⁶⁾ VOR plays an important role in  saccadic movements with small amplitude. During small saccades, the eyes move first and fixate on the target while the head moves later, and thus compensation must be provided by VOR to keep the object on the fovea. However, for larger saccades, the head and eyes move simultaneously in the same direction, and VOR needs to be suppressed. ⁽⁷⁾

The implications of a disrupted vestibulo-ocular reflex include oscillopsia and abnormal nystagmus.⁽⁸⁾

Asymmetrical Tonic Neck Reflex (ATNR):

• ATNR affects eye tracking, midline issues, handwriting, balance, and laterality.⁽⁴⁾
• Poor pursuits (smooth eye movements)
• Focusing problems (accommodation)
• Difficulty keeping place when copying

Figure 3: Asymmetrical Tonic Neck Reflex
[Image courtesy – https://www.teacherspayteachers.com/Product/Asymmetrical-Tonic-Neck-Reflex-ATNR-PDF-Poster-5882111]

Table 1: Major retained Primitive reflexes with their difficulties in visual areas

Moro Reflex	Tonic Labyrinthine Reflex (TLR)	Symmetrical Tonic Neck Reflex (STNR)	Vestibulo- ocular reflex	Asymmetrical Tonic Neck Reflex (ATNR)
Difficulty in ocular movements Decreased visual perception Visual Hypersensitivity	Difficulty in depth and space perception Poor balance Ocular motor difficulties ( reading and writing )	Hand eye coordination Difficulty with readjustment of binocular vision ( focusing from distance to near)	Oscillopsia	Problem with eye tracking Poor eye hand coordination

Treatment Regimen:

Vision therapy is one of the main treatments to integrate these retained primitive reflexes. Optometrists play a major role in vision therapy and teach many exercises to integrate each reflex.

Conclusion:

Primitive reflexes play a major role in visual skills, ocular movements,etc. When these primitive reflexes are not integrated completely, the child may face difficulties in these areas. If a child is found to have retained primitive reflexes, it is necessary to undergo vision therapy to integrate these reflexes. Thus, primitive reflexes have a strong relationship with ocular functions.

 

References:

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2. Primitive reflexes. Physiopedia. (n.d.). [Available at: https://www.physio-pedia.com/Primitive_Reflexes; 23May23;09:10pmAEST]
3. Russ. (2021, August 1). Vision development and milestones. Optometrists.org. [Available at: https://www.optometrists.org/childrens-vision/guide-to-visual-development/guide-to-vision-development/ ; 23May23;09:10pmAEST]
4. Russ. (2021, August 10). Vision therapy for primitive reflexes. Optometrists.org. Retrieved January 29, 2023, [from https://www.optometrists.org/childrens-vision/guide-to-visual-development/vision-therapy-for-primitive-reflexes; 23May23;09:10pmAEST]
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