| TD | tabes dorsalis; tardive dyskinesia; T-cell dependent; temporary disability; terminal device; tetanus... |
|---|---|
| TD50 | median toxic dose |
| TDD | telecommunication device for the deaf; tetradecadiene; thoracic duct drainage; total digitalizing do... |
| TDL | thoracic duct lymph; thymus-dependent lymphocyte; toxic dose level |
| TE | echo-time; expiratory time; tennis elbow; test ear; tetanus; tetracycline; threshold energy; thrombo... |
| equator of lens | The periphery of the lens lying between the two layers of the ciliary zonule. Synonym: equator lentis. (05 Mar 2000) |
|---|---|
| exfoliation of lens | Sheetlike separation of the capsule of the lens; it may occur if the eyes are exposed to intense heat. (05 Mar 2000) |
| fibres of lens | <biology, ophthalmology, physiology> The elongated cells of ectodermal origin forming the substance of the crystalline lens of the eye. Synonym: fibrae lentis. (05 Mar 2000) |
| field lens | <physics> The lower lens in an ocular, the lens nearest the object field. (05 Aug 1998) |
| lamina of lens | One of a series of concentric layers composed of the lens fibres that make up the substance of the lens. (05 Mar 2000) |
| Fresnel lens | <physics> A lens built up, progressively, in zones or steps, each zone with its own individual radius. Considerable spherical correction is attained, and the weight of the lens is greatly reduced. Fresnel lenses were originally designed for lighthouses but they are now attainable for small spotlights, automobile headlights, and similar uses. (05 Aug 1998) |
| front lens | <physics> The front element of a compound lens system, the first lens element which the entering light encounters. See: back lens. (05 Aug 1998) |
| lens | <physics> A transparent optical element, so constructed that it serves to change the degree of convergence or divergence of the transmitted rays. (05 Aug 1998) |
| lens, Bertrand | <microscopy> A small convergent lens placed between objectives and eyepiece. The lens focuses an image of the upper focal plane of the objective on the focal plane of the eyepiece. It is chiefly used with polarized light for inspecting the interference figure. It is also convenient for quickly verifying centreing, size, and uniform illumination of an aperture. (05 Aug 1998) |
| lens capsule | The capsule enclosing the lens of the eye. Synonym: capsula lentis, crystalline capsule, lenticular capsule, phacocyst. (05 Mar 2000) |
| lens capsule, crystalline | The noncellular outer covering of the crystalline lens, secreted by the embryonic anterior and posterior epithelium. The embryonic posterior epithelium later disappears. (12 Dec 1998) |
| lens clock | A device for measuring the radii of the curvature of a spectacle lens. Synonym: lens clock. Origin: Geneva, Switzerland (05 Mar 2000) |
| lens, compound | <microscopy> A lens composed of two or more separate pieces of glass or other optical maternal. These component pieces or elements may or may not be cemented together. A common form of compound lens is a two-element objective, one element being a converging lens of crown glass and the other a diverging lens of flint glass. The combination of suitable glasses or other optical materials (plastics, minerals) properly ground and polished reduces aberrations normally present in a single lens. (05 Aug 1998) |
| lens cortex, crystalline | The portion of the crystalline lens surrounding the nucleus and bound anteriorly by the epithelium and posteriorly by the capsule. It contains lens fibres and amorphous, intercellular substance. (12 Dec 1998) |
| lens, crystalline | The transparent biconvex body of the eye situated between the posterior chamber and the vitreous body, constituting part of the refracting mechanism of the eye. (12 Dec 1998) |