Corneal Ring: From 1 Different Sources
a ring designed to be inserted into the peripheral tissue of the cornea in order to alter the curvature of the corneal surface. It is undergoing trials to assess its ability to correct errors of refraction. In myopia (short-sightedness), for example, the ring would be required to stretch the corneal tissue peripherally and thus flatten the central corneal curvature in order to correct the myopia.
A local anaesthetic agent (see ANAESTHESIA) injected into the circumference of the base of a digit. It numbs the nerves of the ?nger or toe and so permits minor surgery to be performed. Care must be taken to avoid damage to local blood vessels which can lead to GANGRENE.... ring block
See: EYES, INFECTION. ... corneal ulcer
Colloquial term for Hapalochlaena spp.... blue-ringed octopus
Instinctive closing of the eyelids when the surface of the cornea (see EYE) is lightly touched with a ?ne hair.... corneal reflex
Reserving money to be spent for a particular service, such as grants to local authorities.... ring-fencing
See corneal graft.... corneal transplant
See tinnitus.... ringing in the ears
see retraction ring. [L. Bandl (1842–92), German obstetrician]... bandl’s ring
a white or greyish line in the periphery of the cornea, concentric with but separated from the edge by a clear zone. It begins above and below but may become a continuous ring. It consists of an infiltration of fatty material and is common in the elderly (arcus senilis). When it occurs in younger people (arcus juvenilis) it may indicate *hyperlipidaemia. It does not affect vision.... corneal arcus
reflex blinking of both eyes normally elicited by lightly touching the cornea of one eye. This reflex is lost in deep coma, during general anaesthesia, and in death; it is therefore one of the tests used to confirm brainstem death.... corneal reflex
(videokeratography) an imaging technique used to study the shape and refractive power of the cornea in detail. An image projected onto the cornea is analysed by a computer to produce a representation of the shape and refractive power of the corneal surface. Corneal topography has an important role in the management of corneal disease and refractive surgery.... corneal topography
a deposit of iron in the form of a ring in the epithelium of the cornea, which is seen, for example, around the base of the ‘cone’ of the cornea in *keratoconus. It is best visualized using cobalt blue light. [B. Fleischer (1848–1904), German physician]... fleischer ring
a watertight adherent ring placed around an intestinal *stoma and incorporating a flange to which a disposable plastic bag could be attached. It was the forerunner of modern disposable stoma bags.... hollister ring
a brownish-yellow ring in the outer rim of the cornea of the eye. It is a deposit of copper granules and is diagnostic of *Wilson’s disease. When well developed it can be seen by unaided observation, but faint Kayser-Fleischer rings may only be detected by specialized *slit-lamp ophthalmological examination. [B. Kayser (1869–1954), German ophthalmologist; B. Fleischer (1848–1904), German physician]... kayser–fleischer ring
n. (in anatomy) see annulus.... ring
(Ringer’s mixture) a clear colourless *physiological solution of sodium chloride (common salt), potassium chloride, and calcium chloride prepared with recently boiled pure water. The osmotic pressure of the solution is the same as that of blood serum. Ringer’s solution is used for maintaining organs or tissues alive outside the animal or human body for limited periods. Sterile Ringer’s solution may be injected intravenously to treat dehydration. [S. Ringer (1835–1910), British physiologist]... ringer’s solution
a depression in the uterine wall marking the junction between the actively contracting muscle fibres of the upper segment of the uterus and the muscle fibres of the lower segment. This depression is not always visible and is normal. In obstructed labour (e.g. contracted pelvis or malposition of the fetus resulting in shoulder presentation), the muscle fibres of the upper segment become shorter and thicker; the muscle fibres of the lower segment, on the other hand, become elongated and thinner. The junction between the two becomes more distinct as it rises into the abdomen from the pelvis. This abnormal ring is known as Bandl’s ring and is a sign of impending rupture of the lower segment of the uterus, which becomes progressively thinner as Bandl’s ring rises upwards. Immediate action to relieve the obstruction is then necessary, usually in the form of Caesarean section.... retraction ring
a ringlike constriction in the lower part of the gullet (oesophagus). The cause is unclear. Patients may be asymptomatic or experience episodic difficulty in swallowing. Diagnosis is made at gastroscopy or *barium swallow. Antisecretory agents and endoscopic balloon dilatation are reserved for symptomatic patients. [R. Schatzki (20th century), German-born US physician]... schatzki ring
the ring of lymphoid tissue formed by the *tonsils. [H. W. G. von Waldeyer (1836–1921), German anatomist]... waldeyer’s ring
a ringlike opacity on the posterior vitreous surface, arising as a result of a posterior *vitreous detachment. It is seen as a ring-shaped *floater.... weiss ring
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