cone of light
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1. a solid figure or body having a circular base and tapering to a point.
2. one of the conelike structures which, with the rods, form the light-sensitive elements of the retina; the cones make possible the perception of color. See also eye and vision. Called also retinal cone.
3. in radiology, a conical or open-ended cylindrical structure formerly used as an aid in centering the radiation beam and as a guide to source-to-film distance. Cones were commonly attached to the x-ray tube prior to the use of the collimator.
4. in root canal therapy, a solid substance with a tapered form, usually made of gutta-percha or silver, fashioned to conform to the shape of a root canal.
ether cone a cone-shaped device used over the face in administration of ether for anesthesia.
gutta-percha cone in root canal therapy, a plastic radiopaque cone made from gutta-percha and other ingredients, available in standard sizes according to the dimensions of root canal reamers and files; used to fill and seal the canal along with sealer cements. Called also gutta-percha point.
cone of light the triangular reflection of light seen on the tympanic membrane.
pressure cone the area of compression exerted by a mass in the brain, as in transtentorial herniation.
retinal cone cone (def. 2).
silver cone silver point.
1. Synonym(s): pupillary reflex
2. a red glow reflected from the fundus of the eye when a light is cast on the retina, as in retinoscopy; Synonym(s): eye reflex, fundus reflex