The corneal reflex, also known as the blink reflex or eyelid reflex,[1] is an involuntary blinking of the eyelids elicited by stimulation of the cornea (such as by touching or by a foreign body), though it could result from any peripheral stimulus. Stimulation should elicit both a direct and consensual response (response of the opposite eye). The reflex occurs at a rapid rate of 0.1 seconds. The purpose of this reflex is to protect the eyes from foreign bodies and bright lights (the latter known as the optical reflex).[2] The blink reflex also occurs when sounds greater than 40–60 dB are made.[3]
Corneal reflex
Purpose
Examination of corneal reflex is part of some neurological tests.
Use of contact lenses may diminish or abolish the testing of this reflex.
Flowchart depicting the corneal reflex pathway.
The optical reflex, on the other hand, is slower and is mediated by the visual cortex, which resides in the occipital lobe of the brain. The reflex is absent in infants under nine months.
The examination of the corneal reflex is a part of some neurological exams, particularly when evaluating coma, such as FOUR score. Damage to the ophthalmic branch (V1) of the trigeminal nerve results in absent corneal reflex when the affected eye is stimulated. Stimulation of one cornea normally has a consensual response, with both eyelids normally closing.
RatesEdit
When awake, the lids spread the tear secretions over the corneal surface, on a typical basis of 2 to 10 seconds (though this may vary individually). However, blinking is not only dependent on dryness and/or irritation.[citation needed] A brain area, the globus pallidus of the basal ganglia, contains a blinking center that controls blinking. Nonetheless, the external stimuli are still involved. Blinking is linked with the extraocular muscles. Blinking is often concurrent with a shift in gaze, and it is believed that this helps the movement of the eye.[4]
^Garde, M.M., & Cowey, A. (2000). "'Deaf hearing': Unacknowledged detection of auditory stimuli in a patient with cerebral deafness". Cortex 36(1), 71–80.
^C, Evinger; Ka, Manning; Jj, Pellegrini; Ma, Basso; As, Powers; Pa, Sibony (1994). "Not Looking While Leaping: The Linkage of Blinking and Saccadic Gaze Shifts". Experimental Brain Research. 100 (2): 337–344. doi:10.1007/BF00227203. PMID 7813670. S2CID 6480046. Retrieved 2020-05-30.
October 22, 2023
corneal, reflex, corneal, reflex, also, known, blink, reflex, eyelid, reflex, involuntary, blinking, eyelids, elicited, stimulation, cornea, such, touching, foreign, body, though, could, result, from, peripheral, stimulus, stimulation, should, elicit, both, di. The corneal reflex also known as the blink reflex or eyelid reflex 1 is an involuntary blinking of the eyelids elicited by stimulation of the cornea such as by touching or by a foreign body though it could result from any peripheral stimulus Stimulation should elicit both a direct and consensual response response of the opposite eye The reflex occurs at a rapid rate of 0 1 seconds The purpose of this reflex is to protect the eyes from foreign bodies and bright lights the latter known as the optical reflex 2 The blink reflex also occurs when sounds greater than 40 60 dB are made 3 Corneal reflexPurposeExamination of corneal reflex is part of some neurological tests The reflex is mediated by the nasociliary branch of the ophthalmic branch V1 of the trigeminal nerve CN V sensing the stimulus on the cornea only afferent fiber the temporal and zygomatic branches of the facial nerve CN VII initiating the motor response efferent fiber the center nucleus is located in the pons of the brainstem Use of contact lenses may diminish or abolish the testing of this reflex Flowchart depicting the corneal reflex pathway The optical reflex on the other hand is slower and is mediated by the visual cortex which resides in the occipital lobe of the brain The reflex is absent in infants under nine months The examination of the corneal reflex is a part of some neurological exams particularly when evaluating coma such as FOUR score Damage to the ophthalmic branch V1 of the trigeminal nerve results in absent corneal reflex when the affected eye is stimulated Stimulation of one cornea normally has a consensual response with both eyelids normally closing Rates EditWhen awake the lids spread the tear secretions over the corneal surface on a typical basis of 2 to 10 seconds though this may vary individually However blinking is not only dependent on dryness and or irritation citation needed A brain area the globus pallidus of the basal ganglia contains a blinking center that controls blinking Nonetheless the external stimuli are still involved Blinking is linked with the extraocular muscles Blinking is often concurrent with a shift in gaze and it is believed that this helps the movement of the eye 4 See also EditMenace reflex ReflexReferences Edit Eyelid Reflex an overview ScienceDirect Topics www sciencedirect com Retrieved 2021 06 05 eye human Encyclopaedia Britannica from Encyclopaedia Britannica 2006 Ultimate Reference Suite DVD 2009 Garde M M amp Cowey A 2000 Deaf hearing Unacknowledged detection of auditory stimuli in a patient with cerebral deafness Cortex 36 1 71 80 C Evinger Ka Manning Jj Pellegrini Ma Basso As Powers Pa Sibony 1994 Not Looking While Leaping The Linkage of Blinking and Saccadic Gaze Shifts Experimental Brain Research 100 2 337 344 doi 10 1007 BF00227203 PMID 7813670 S2CID 6480046 Retrieved 2020 05 30 Retrieved from https en wikipedia org w index php title Corneal reflex amp oldid 1181081509, wikipedia, wiki, book, books, library,
