(dilation of the pupil with light touch to the back of the neck. Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors. The contralateral efferent limb causes consensual light reflex of the contralateral pupil. The accommodation neural circuit: The circuitry of the accommodation response is more complex than that of the pupillary light reflex (Figure 7.6). Pathway: The trigeminal nerve or cervical pain fibers, which are part of the lateral spinothalamic tract, carry the afferent inputs of the ciliospinal reflex. This page was last edited on 7 January 2023, at 06:24. The oculocardiac reflex is a dysrhythmic physiological response to physical stimulation of the eye or adnexa specifically, it is defined by a 1020% decrease in the resting heart rate and/or the occurrence of any arrhythmia induced by traction or entrapment of the extraocular muscles and/or pressure on the eyeball sustained for at least 5 seconds. The pupillary light reflex pathway involves the optic nerve and the oculomotor nerve and nuclei. Each efferent limb has nerve fibers running along the oculomotor nerve (CN III). The direct response is the change in pupil size in the eye to which the light is directed (e.g., if the light is shone in the right eye, the right pupil constricts). Emergency physicians routinely test pupillary light reflex to assess brain stem function. Direct and consensual responses should be compared in the reactive pupil. Tactile stimulation of the cornea results in an irritating sensation that normally evokes eyelid closure (an eye blink). Though opioid drugs tend to be among the most common that affect pupil constriction, other medications may also have an effect on the pupils’ ability to dilate.Five basic components of the pupillary light reflex pathway Non-Opioid Drugs That Can Cause Constricted Pupils Illegal forms of opioids or opiates include: During use, opioids tend to stimulate the parasympathetic nerve and cause constricted pupils. ![]() Generally, drugs classified as opioids will constrict pupils when the drug is ingested. Generally, stimulants dilate pupils and depressants (like opioids) cause constricted pupils. But substance use and abuse can affect the central nervous system and interfere with the ability of the eyes to react appropriately. Usually surrounding light causes stimulation of the relevant nerve to dilate or constrict the pupils. Pupils that do not dilate or constrict properly can create, or be a symptom of, serious vision problems. Pupil dilation and constriction is an important function that controls the amount of light that enters the eye and allows a person to see properly. When the sympathetic nerve is stimulated, pupils dilate. Normally, when the parasympathetic nerve is activated, it causes pupils to constrict, or narrow. Pupil constriction and dilation are controlled by the sympathetic and parasympathetic nervous systems in the brain. One of the more noticeable, and uncontrollable, ways is dilated or constricted pupils. ![]() Physiological changes in the brain can appear in a variety of ways in the rest of the body. On the other hand, depressants generally inhibit brain activity causing drowsiness, lethargy, decreased heart rate, blood pressure, and a sense of calm. For instance, stimulants tend to affect the brain in a way that increases alertness, energy levels, heart rate and blood pressure. How a particular drug affects the body often depends on the type of drug being used.
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