Bell's phenomenon (also known as the palpebral oculogyric reflex) is a

medical sign Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormality showin ...

that allows observers to notice an upward and outward movement of the eye, when an attempt is made to close the eyes. The upward movement of the eye is present in the majority of the population, and is a defensive mechanism. The

phenomenon A phenomenon ( : phenomena) is an observable event. The term came into its modern philosophical usage through Immanuel Kant, who contrasted it with the noumenon, which ''cannot'' be directly observed. Kant was heavily influenced by Gottfried W ...

is named after the Scottish

anatomist Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its ...

surgeon In modern medicine, a surgeon is a medical professional who performs surgery. Although there are different traditions in different times and places, a modern surgeon usually is also a licensed physician or received the same medical training as ...

, and

physiologist Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical a ...

Charles Bell Sir Charles Bell (12 November 177428 April 1842) was a Scotland, Scottish surgeon, anatomist, physiologist, neurologist, artist, and philosophical theologian. He is noted for discovering the difference between sensory nerves and motor nerves in ...

. Bell's phenomenon is a normal defense reflex present in about 75% of the population, resulting in elevation of the globes when blinking or when threatened (e.g. when an attempt is made to touch a patient's

cornea The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical power ...

). It becomes noticeable only when the

orbicularis oculi muscle The orbicularis oculi is a muscle in the face that closes the eyelids. It arises from the nasal part of the frontal bone, from the frontal process of the maxilla in front of the lacrimal groove, and from the anterior surface and borders of a short ...

becomes weak as in, for example, bilateral facial

palsy Palsy is a medical term which refers to various types of paralysisDan Agin, ''More Than Genes: What Science Can Tell Us About Toxic Chemicals, Development, and the Risk to Our Children;; (2009), p. 172. or paresis, often accompanied by weakness and ...

associated with

Guillain–Barré syndrome Guillain–Barré syndrome (GBS) is a rapid-onset muscle weakness caused by the immune system damaging the peripheral nervous system. Typically, both sides of the body are involved, and the initial symptoms are changes in sensation or pain often ...

. It is, however, present behind forcibly closed eyelids in most healthy people and should not be regarded as a

pathognomonic Pathognomonic (rare synonym ''pathognomic'') is a term, often used in medicine, that means "characteristic for a particular disease". A pathognomonic sign is a particular sign whose presence means that a particular disease is present beyond any doub ...

sign. Also, traumatic abrasions are generally located in the central or inferior cornea due to Bell's phenomenon. Bell's phenomenon does not occur during short blinks.

References

* * Basic Ophthalmology: Page 110, Ocular and Orbital Injuries, Vasim Lala. Ophthalmology {{eye-stub