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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).
In the fields of optometry and ophthalmology, the Hirschberg test, also Hirschberg corneal reflex test, is a screening test that can be used to assess whether a person has strabismus (ocular misalignment). A photographic version of the Hirschberg test is used to quantify strabismus. [1]
Cervico-spinal reflex; Churchill–Cope reflex; Corneal reflex — blinking of both eyes when the cornea of either eye is touched. Coronary reflex; Cough reflex — a rapid expulsion of air from the lungs after sudden opening of the glottis, and usually following irritation of the trachea.
A reflex blink is not necessarily a conscious blink either; however it does happen faster than a spontaneous blink. [1] Reflex blink may occur in response to tactile stimuli (e.g., corneal, eyelash, skin of eyelid, contact with eyebrow), optical stimuli (e.g. dazzle reflex, [20] or menace reflex) or auditory stimuli (e.g., menace reflex).
Brainstem reflexes Respiration 4 Eyelids open or opened, tracking, or blinking to command Thumbs-up, fist, or peace sign Pupil and corneal reflexes present Not intubated, regular breathing pattern 3 Eyelids open but not tracking Localizing to pain One pupil wide and fixed Not intubated, Cheyne–Stokes breathing pattern 2
There is a global shortage of corneal donations, severely limiting the availability of corneal transplants across most of the world. A 2016 study found that 12.7 million visually impaired people were in need of a corneal transplant, with only 1 cornea available for every 70 needed. [ 31 ]
The reflex involves consensual blinking of both eyes in response to stimulation of one eye. This is due to the facial nerves' innervation of the muscles of facial expression, namely orbicularis oculi, responsible for blinking. Thus, the corneal reflex effectively tests the proper functioning of both cranial nerves V and VII.
For example, an animal with polioencephalomalacia will lack the menace reflex, but will still have the pupillary light reflex. Polioencephalomacia damages the visual cortex, impairing the menace response, but leaves the optic nerve, oculomotor nucleus, and oculomotor nerve intact, leaving the pupillary light reflex unaffected. Contrastingly, an ...