| convergence excess | That condition in which an oesophoria or esotropia is greater for near vision than for far vision. (05 Mar 2000) |
|---|---|
| convergence insufficiency | That condition in which an oesophoria or esotropia is more marked for far vision than for near vision. (05 Mar 2000) |
| convergence nucleus of Perlia | A small cell group located between the somatic cell columns of the oculomotor nuclei. Since it is placed between the groups of motor neurons innervating, respectively, the left and right medial rectus muscles, the nucleus is considered to possibly represent an integrating mechanism for ocular convergence. Synonym: convergence nucleus of Perlia, Spitzka's nucleus. (05 Mar 2000) |
| convergence, ocular | The turning inward of the lines of sight toward each other. (12 Dec 1998) |
| convergence-retraction nystagmus | Irregular, jerky nystagmus combining convergence and retraction of the eye into the orbit, especially on attempting an upward gaze. Synonym: Koerber-Salus-Elschnig syndrome. (05 Mar 2000) |
| convergent | Tending toward a common point. (05 Mar 2000) |
| Convergent Beam Electron Diffraction | <microscopy> An electron probe is tightly focused on a transmission electron microscopy specimen and the resulting pattern of diffracted electrons is observed. The patterns contains information on the crystal symmetry and atomic and electronic structure of the sample. Regions as small as 0.2 nm may be examined. Acronym: CBED (05 Aug 1998) |
| convergent evolution | The process where two unrelated structures in unrelated organisms evolve to perform similar functions. (The structures are called analogous structures.) For example: the wings of bats, birds, and insects evolved separately from each other but all are used to perform the function of flying. For another example: the complex eyes of vertebrates, cephalopods (squid and octopus), cubozoan jellyfish, and arthropods (insects, spiders, crustaceans) evolved separately, but all perform the function of vision. (09 Oct 1997) |
| convergent squint | Cross-eyed. (27 Sep 1997) |
| convergent strabismus | Cross-eyed. (27 Sep 1997) |
| converging meniscus | A convexoconcave lens in which the power of the convexity exceeds that of the concavity. Synonym: positive meniscus. (05 Mar 2000) |
| conversion | An unconscious defense mechanism by which the anxiety that stems from intrapsychic conflict is converted and expressed in a symbolic somatic. Origin: L. Con = with, versio = turning (18 Nov 1997) |
| conversion disorder | A disorder whose predominant feature is a loss or alteration in physical functioning that suggests a physical disorder but that is actually a direct expression of a psychological conflict or need. (12 Dec 1998) |
| conversion electron | An internal conversion electron. (05 Mar 2000) |
| conversion hysteria | Hysteria characterised by the substitution, through psychic transformation, of physical signs or symptoms for anxiety; generally restricted to such major symptoms as blindness, deafness, and paralysis, or lesser ones such as blurred vision and numbness. Synonym: conversion hysteria neurosis, conversion neurosis, conversion reaction. (05 Mar 2000) |