| multifocal lens | A lens with segments providing two or more powers; commonly, a trifocal lens. (05 Mar 2000) |
|---|---|
| multifocal | Arising from or pertaining to many locations. (16 Dec 1997) |
| multifocal atrial tachycardia | A rapid heart rate that is generated from multiple locations within the atria. Multifocal atrial tachycardia (MAT) tends to be in the range of 100 to 180 beats per minute. MAT can be seen in association with COPD, pneumonia, CHF, lung cancer, diabetes, pulmonary embolism, theophylline toxicity, coronary artery disease or digoxin toxicity. Origin: Gr. Kardia = heart (27 Sep 1997) |
| multifocal choroiditis | Macular, peripapillary, and peripheral choroiditis, often designated presumed ocular histoplasmosis. (05 Mar 2000) |
| multifocal osteitis fibrosa | The occurrence of lesions of fibrous dysplasia in multiple bones, commonly on one side of the body; may occur with areas of pigmentation and endocrine dysfunction (McCune-Albright syndrome). Synonym: multifocal osteitis fibrosa, osteitis fibrosa disseminata. (05 Mar 2000) |
| progressive multifocal leukoencephalopathy | <radiology> Demyelinating disease due to papovavirus, seen in immunosuppressed hosts: lymphoma, leukaemia, AIDS, TB, sarcoidosis, organ transplant, most prominent in pareito-occipital white matter, NO contrast enhancement (12 Dec 1998) |
| leukoencephalopathy, progressive multifocal | Rare demyelinating disease of the central nervous system which develops in immunocompromised patients secondary to lymphoproliferative disease, immunosuppressive therapy, autoimmune disorders, or aids. It is caused by the jc virus, a polyomavirus. (12 Dec 1998) |
| achromatic lens | A compound lens made of two or more lens's having different indices of refraction, so correlated as to minimise chromatic aberration. (05 Mar 2000) |
| acoustic lens | In ultrasonography, a lens used to focus or diverge a sound beam; may be simulated by electronic manipulation of signals. (05 Mar 2000) |
| anterior pole of lens | The central point on the anterior surface of the lens of the eye. Synonym: polus anterior lentis. (05 Mar 2000) |
| anterior surface of lens | The anterior surface of the lens of the eye. Synonym: facies anterior lentis. (05 Mar 2000) |
| aplanatic lens | A lens designed to correct spherical aberration and coma (q.v.). Synonym: periscopic meniscus. (05 Mar 2000) |
| apochromatic lens | A compound lens designed to correct both spherical and chromatic aberrations. (05 Mar 2000) |
| asphenc lens | <physics> A lens made aplanatic by grinding the outer zones to a greater radius than the inner zones. Aplanatic condensers can be made in this way. A simple aspheric lens is widely used as a lamp condenser because of its efficiency in converging light rays to one focal plane. (05 Aug 1998) |
| aspheric lens | A lens with a paraboloidal surface that eliminates spherical aberration. (05 Mar 2000) |