Disappears in response to light

Introduction The change in the pupil's disappearance of light reflection. When the pupil is illuminated by a flashlight, the change is small, and the pupil increase is not obvious after the light source is removed. This condition is called the pupil is unresponsive to light. When the pupil does not respond to light reflection, it is called the reaction to light disappears. The case where the light reaction disappears is often considered to be caused by damage to the brain nerves, and can also be seen in cases caused by diseases such as trauma or encephalitis or blood vessels or embolism in the brain. Both direct and indirect reflexes disappeared and were seen in deep coma or ipsilateral oculomotor damage. Direct reflection of light disappears, indirect reflection of light, seen in the ipsilateral optic nerve.

Cause

The afferent fibers reflected by the light travel in the optic nerve and the optic tract. When approaching the lateral geniculate body, the inner bundle is separated to reach the superior colliculus, and the nucleus of the anterior region of the apex is stopped. The interneurons connect the oculomotor sympathetic sympathetic sympathetic sympathetic sympathetic sympathetic sympathetic sympathetic sympathetic sympathetic sympathetic nucleus (EW), or the autonomic nucleus. Therefore, when one eye is stimulated, the pupil of the other eye also shrinks (indirectly responds to light). The reflex pathway starts from the EW nucleus and moves along the oculomotor nerve to the ciliary ganglion. The last neuron is emitted from the ciliary ganglion cells to the pupil sphincter.

Both direct and indirect reflexes disappeared and were seen in deep coma or ipsilateral oculomotor damage. Direct reflection of light disappears, indirect reflection of light, seen in the ipsilateral optic nerve.

an examination

Related inspection

Eye and sacral area CT examination ophthalmoscopy

In normal people, when the flashlight directly illuminates one side of the pupil, it can be observed that the side pupil is immediately reduced when it is stimulated by light. At this time, the pupil can be immediately recovered after removing the light source. The contralateral pupil was observed again in the same manner. This is a direct reflection of light.

Place one hand vertically between the two eyes to block the light from the flashlight to the opposite side. At this time, one side of the pupil is illuminated by a flashlight, and the pupil of the other side is immediately reduced, and the pupil of the light is removed and restored immediately. In the same way, the contralateral pupil was examined, and the performance was the same as above. This is an indirect reflection of light.

Both direct light reflection and indirect light reflection are functional activities for detecting pupils. If the pupil is illuminated by a flashlight, the change is small, and the pupil increase is not obvious after the light source is removed. This condition is called the pupil is unresponsive to light. When the pupil does not respond to light, it is called the reaction to light disappears.

Differential diagnosis

1. Pupil abnormality: The pupil has extensive connection with various parts of the body. Its opening and contraction are affected by various factors, and its changes are clinically important. When the diameter of the sputum is greater than 5 mm, and the sag is continuous, the sputum is said to be large. If the pupil diameter is less than 2mm, the pupil is said to be reduced. Sometimes through the change of the pupil, it can reflect some lesions in the body, and some lesions of the nervous system can also make a diagnosis based on the changes of the pupil.

2, contraction, eyelid drooping and eyeball retraction: the so-called Horner's syndrome, refers to a group of ocular symptoms caused by the damage of the autonomic nerves of the cervical sympathetic ganglia. This disease can occur in any part of the cervical sympathetic pathway. It is extremely rare to be caused by central nervous system lesions above the first thoracic cord. Mainly manifested as: the pupil of the affected side is reduced, the eye is cracked, the eyeball is invaginated, the face is less sweaty or sweat-free. This phenomenon is called Horner syndrome. Also known as Horner's syndrome.

3, oculomotor nerve paralysis: oculomotor nerve paralysis, the upper eyelid sag, the eyeball inward, upward and downward activities are restricted and exotropia and diplopia appear, and pupil dilated, adjustment and aggregation reflex disappear. The cyclical phenomenon is caused by the rhythmic impulse of the midbrain nerve center directly acting on the oculomotor nerve.

4. Cerebral palsy: When there is a space-occupying lesion in a certain cavity in the cranial cavity, the pressure of the sub-chamber is higher than that of the adjacent sub-chamber, and the brain tissue is displaced from the high-pressure area to the low-pressure area, thereby causing a series of clinical Syndrome, called cerebral palsy.

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