| ultraviolet therapy | The use of ultraviolet electromagnetic radiation in the treatment of disease, usually of the skin. This is the part of the sun's spectrum that causes sunburn and tanning. Ultraviolet a, used in puva, is closer to visible light and less damaging than ultraviolet b, which is ionizing. (12 Dec 1998) |
|---|---|
| alternating light test | Test to detect a relative afferent defect in one eye by watching pupillary movements. With the patient fixing in the distance, the light is held on each eye for about a second, and quickly moved to the other eye. Assuming no defect of the innervation to the iris sphincter in one eye (which would produce an anisocoria in light), the eye with the weaker light response has a relative afferent pupillary defect. This asymmetry of pupillomotor input can be estimated by holding neutral density filters in front of the better eye until the pupillary responses of the two eyes are balanced. Synonym: swinging light test. (05 Mar 2000) |
| Begg light wire differential force technique | An orthodontic appliance utilizing small gauge labial wires with expansion and contraction loops formed into it and attached to bands fitted to individual teeth; sometimes called Begg light wire differential force technique. (05 Mar 2000) |
| gene rearrangement, b-lymphocyte, light chain | Ordered rearrangement of b-lymphocyte variable gene regions coding for the kappa or lambda light chains, thereby contributing to antibody diversity. It occurs during the second stage of differentiation of the immature b-lymphocyte. (12 Dec 1998) |
| ray, light | <microscopy> The term applied to the lines perpendicular to the wavefronts of waves of light to indicate their direction of travel in an isotropic medium. Note the wave normal and the ray do not coincide in isotropic media. (05 Aug 1998) |
| reflected light | Light directed backward from a mirror. (05 Mar 2000) |
| refracted light | Bent rays of light changed in passage from one transparent medium to another of unequal density. See: refraction. (05 Mar 2000) |
| visible light | <physics> Electromagnetic radiation with wavelengths between 400 nanometres and 750 nanometres. Electromagnetic radiation within this range can be detected by the human eye. Colours depend on the wavelength lengths, a short wavelength (the 400 nm side) looks blue and a long wavelength (the 750 nm side) looks red. (09 Oct 1997) |
| metals, light | Metals with low specific gravity, typically smaller than 5, characterised by a single valence (1, 2, or 3), a simple spectrum, strong electromotive force (positive), and colourless compounds. (12 Dec 1998) |
| minimum light | Threshold of visual sensation, the minimal light intensity evoking a visual sensation. Synonym: achromatic threshold, minimum light threshold. (05 Mar 2000) |
| minimum light threshold | Threshold of visual sensation, the minimal light intensity evoking a visual sensation. Synonym: achromatic threshold, minimum light threshold. (05 Mar 2000) |
| cold light | Fluorescent light as opposed to incandescent light. (05 Mar 2000) |
| monochromatic light | <microscopy> Light composed of one wavelength. It may be obtained by the use of a laser or by gaseous discharge tubes in combination with proper filters. An approximation is obtained by interference filters or monochromators. (05 Aug 1998) |
| plane-polarized light | <chemistry> Light which is passed through a filter which blocks out all the light except that which ocillates in one plane. (09 Jan 1998) |
| cone of light | A triangular area at the anterior inferior part of the tympanic membrane, running from the umbo to the periphery, where there is seen a bright reflection of light. Synonym: cone of light, light reflex, Politzer's luminous cone, red reflex, Wilde's triangle. Malacarne's pyramid, a lobule on the undersurface of the cerebellum, the posterior portion of the vermis. (05 Mar 2000) |