Doll’s Eye Reflex: Principle, Cause, Procedure

This post on Doll’s Eye Reflex topics are related to its causes, principles, positive and negative doll’s eye reflex or OCD reflex, and step by step procedure, and a case study.

This post has a FAQ section that further enriches your knowledge of the doll’s eye reflex.

What is Doll’s Eye Reflex?

It is an eye’s reflex movement test, to estimate the brain functioning in comatose or servery lethargic patients.

The word “doll’s eye” somehow can be correlated to toy dolls that have mechanical eye function i.e. even with the movement of their head, their eyes were fixed at a position and seemed to move opposite to the direction of head movement.

Why doll’s eye is performed?

As stated earlier, the doll’s eye reflex test is performed to test the test brain stem function in comatose or servery lethargic patients.

In other words, it is a simple test to indicate the brain death condition of a person.

What is the principle of Doll’s eye reflex test?

Doll’s eye reflex test is based on the oculo-cephalic reflex phenomenon (OCR) in comatose patients and young infants.

The OCR is controlled by the brainstem, which receives signals from the vestibular nerve and transmits signals to the oculomotor nerve.

Note 1: Oculo-Cephalic Reflex: It is a reflex that stabilizes the image on the retina during head movement by producing eye movement opposite to the head movement.

The nerves that are responsible for these reflexes are the oculomotor nerves and the 8th nerve. In conscious alert adults, the OCR is always present but is automatically suppressed.

So, if the patient has an intact brain stem, it means that oculomotor nerves and 8th nerves are functioning which are finally responsible for dolly’s eye reflexes generally termed as positive/ normal doll’s reflex.

And if the mid-obits of the eye stay fixed, then it is an indication of severe brain damage or brain death which is called a negative doll’s eye.

Note 2: There is another term called Vertibuloocular Reflex. Oculo- Cephalic Reflex is a form of Vertibuloocular Reflex (VOR), that is responsible for stabilizing the vision during head movement.

The VOR does not depend on visual input. It can be elicited by caloric (hot or cold) stimulation of the inner ear and works even in total darkness or when the eyes are closed.

What causes the Doll’s Eye Reflex and its interpretation?

In order to stabilize the visual world on the retina, the eyes show the dolly’s eye phenomenon in a comatose person.

There are basically three types of reflexes involved in the maintenance of a stable visual field includes:
1. Extraretinal signals of head motion
2. Retinal signals
3. Neuro control of stabilization reflex

1. Extraretinal signals of head motion:

It is a type of Non-visual signal used by the CNS to encode the position of the eyes in orbits.

2. Retinal Signals:

Due to the head rotation, the retinal image motion of the visual field also tries to maintain the retinal point image.

3. Neuro control of stabilization reflex:

The three semi-circular canals convert the head motion signals into a neural stimulus that triggers the doll’s eye reflex or vestibulo–ocular reflex.

What are Positive/ Normal and Negative Doll’s Eyes Reflexes?

In a positive or normal doll’s eyes reflex, the eyes move in the counter direction to the head movement due to the presence of extraretinal signals of head motion, retinal signals, and neuro control of stabilization reflex.

While negative doll’s eye reflex means that the eyes don’t show any counter-measures to the head movement, and the motor functionality of oculomotor nerves and 8th nerves get disturbed, which indicates a brain-dead person.

Causes for a Negative Doll’s Eye Reflex

In the case where the doll’s eye reflexes are absent then there may be due to one or more lesions in the following pathways:

1. The vestibular nerve and labyrinth
2. The neck proprioceptors
3. Cranial nerves 3 and 6
4. The external ocular muscles

Other regions that can cause difficulty in assessing Doll’s Eye Reflex:
1. Orbital Edema: Impairing ability of the examiner to open eyes
2. Conjunctival Edema: Impairing ability of the eyes to move appropriately.

Note 3: False-Positive Doll’s eye reflex:
There might be a false-positive doll’s eye reflex. This is majorly due to the influence of some medications like anesthesia.

How do you assess the doll’s eyes? Neuro Assessment (Procedure)

There are basically 6 steps involved in the doll’s eye neuro assessment test for obtaining maximum stimulation and result:

Step 1: Assess the conscious level of the Patient: Before starting to maneuver the patient’s current position is thoroughly assessed.

Step 2: Placing the patient in the supine position: The patient must be placed in a supine position. And head should be elevated at least 30° to minimize any intracranial pressure while assessing the eye movement of the patient.

Step 3: Hold the eyelids: Try to hold the eyelids with the thumb and index finger of one hand.

Step 4: Rotate the head Head in a single direction and observe: Gently rotate the head in one direction. The eyes should move in the counter direction. This deviation should be smooth and conjugate. The head should be kept steady for a while and the eyes should slowly return to the midline.

Step 5: Rotate the head to another side: Again gently rotate the head to another direction and hold the position for a few seconds. Again the counter-movement of eyes and slow return to midline clarify that the patient has an intact brainstem.

Step 6: Switch to Up-side movement of the head: Tilting the head down results in the opening of eyelids and counter-movement of eyes also seen, which is generally termed as the doll’s head phenomenon.

Things to avoid while performing doll’s eye reflex test

1. Never perform this test on a normal and alert person.
2. Never perform the doll’s eye reflex test if a patient has a cervical spine fracture or injury.

Doll’s Eye Reflex in Newborns

Literature Review

The OCR can be seen only in comatose patients and in young normal infants. In the unconscious adult with a head injury, it serves as a measure to identify the integrity of the brainstem or vestibular system.

And in the case of the developing infant, the visible doll’s eye reflexes first develop a normal eye-righting phenomenon before the OCR is suppressed.

As stated earlier, the doll’s OCR reflex is controlled by the brainstem, which receives and transmits signals from the vestibular to the oculomotor nerve respectively. And in conscious alert adults, the OCR is always present but is automatically suppressed.

Two major outcomes of the study

1. OCR Suppressed period: In the case of the growing infant, studies show that these doll’s eye reflexes automatically get suppressed in a period of about 11.5–20 weeks.
2. Growth Pathway: Another major part of this study is, that in newborn babies, there is initially a considerable lag between the head and eye movements.
   But as the baby grows and matures, the eyes are able to adjust more rapidly to the action of head movement.

Note 4: What if the OCR reflex is never suppressed?
If these reflexes never get suppressed then it may result in impaired movement of the eyes to the head movement. Then the individuals would be unable to turn their heads to see something located outside their center field of vision.

So, after the period of 20 weeks, an infant can properly look at the object that is out of the central field of vision by turning the eyes towards the side of the head rotation while maintaining alignment with the macula.

Note 5: Macula; It is the central area of the retina and it gives us the ability to see “20/20” and provides the best color vision.

The bottom line of the study on Doll’s eye reflex in infants

The process of suppression of the OCR in healthy growing infants is longitudinal and is part of the normal maturation of the visual system.

In infants, the doll’s eye reflexes are commonly suppressed by age 11.5–20 weeks.

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Frequently Asked Questions (FAQ)

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References:

• https://www.ncbi.nlm.nih.gov/books/NBK542281/ [PubMed]
• https://www.ncbi.nlm.nih.gov/pubmed/23648598 [PubMed]
• Sole ML, et al. Introduction to Critical Care Nursing, 4th edition. W.B. Saunders Co., 2005
• https://journals.lww.com/nursing/fulltext/2005/06000/checking_for_oculocephalic_reflex.16.aspx [URL]
• https://www.ncbi.nlm.nih.gov/pubmed/20450249 [PubMed]

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