point(redirected from centration distance)
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pointVox populi A small place. See Alarm point, Blockade point, Breakpoint point, Cell cycle restriction point, Checkpoint point, Critical control point, Dilution end point, Distal point, Dose point, Eye reference point, Fixed point, Flashpoint, Isobetic point, Joint point, Limit point, Loo point, Matrix point, McBurney's point, Murphy's point, Myofascial trigger point, Pressure point, Reorder point, Saddle point, Saddle node point, Satellite point, Shu point, Trigger point.
aplanatic point's See aplanatic focus.
break point The point at which diplopia occurs when increasing prism or lens power during binocular fixation. See blur point; relative convergence.
cardinal point's Six points on the optical axis of a lens system or thick lens: the two principal foci, the two principal points and the two nodal points. (Sometimes, this definition also includes the axial object and image points.) (Fig. P14) Syn. gaussian points (some authors consider this term synonymous, although it does not include the two nodal points). See cardinal planes.
centration point The point at which the optical centre (of a lens) is to be located in the absence of a prescribed prism, or after any prescribed prism has been neutralized. If the centration point is not specified, it is located at the standard optical centre position (British Standard). See standard optical position centre; decentration.
conjugate point's See conjugate distances.
point of convergence 1. The point of intersection of the lines of sight. 2. The point to which rays of light converge.
corresponding retinal point's See retinal corresponding points.
distance visual point (DVD) An assumed position of the visual point on a lens used for distance vision under given conditions, normally when the eyes are in the primary position.
point of divergence The point from which rays of light diverge
.equivalent point's See nodal points.
far point of accommodation See far point of accommodation.
far point of convergence See convergence, far point of.
point of fixation See point of fixation.
focal point See principal focus.
gaussian p's . The two principal points and the two focal points on the optical axis of a lens system. See cardinal points.
image p . The point at which an object point is formed by an optical system.
of incidence The point at which a ray of light intersects a refracting or reflecting surface.
lacrimal point See lacrimal punctum.
near point of accommodation See near point of accommodation.
near point of convergence See near point of convergence.
near visual point (NVP) An assumed position of the visual point on a lens used for near vision under given conditions. See visual point.
neutral point 1. In retinoscopy, it is the point at which the sight hole of the retinoscope is conjugate with the patient's retina. At this point, no reflex motion can be seen by the examiner and the entire pupil is illuminated completely, or is completely dark. This is obtained in a myopic eye when the retinoscope is placed at the far point of accommodation. When testing emmetropes and hyperopes this neutral point is reached when sufficient converging lens power has been added in order to displace the far point (artificially) to the sight hole of the retinoscope. See conjugate distances.
nodal point's In a centred optical system they are a pair of conjugate points on the axis which have the property that any incident ray which passes through the first nodal point leaves the system as though from the second nodal point and parallel to the incident ray. Thus the refracted ray is unchanged in direction, although displaced. The distance between the two nodal points is equal to the distance between the two principal points. When the refractive indices on each side of the system are equal, as in the case of a thick lens in air, the principal and nodal points coincide. They are then called equivalent points. In a single refracting surface, the nodal points coincide with the centre of curvature, while the principal points coincide with the vertex of the surface (Figs. P12 and P14). See optical centre; principal plane; vertex.
null p . See nystagmus.
point object See point object.
principal point's The points of intersection of the principal planes with the optical axis. The principal points are the usual reference points from which the focal lengths and the object and image distances are measured (Figs. P12 and P14). See equivalent power.
recovery point The point at which fusion is regained on decreasing the prism or lens power which originally induced diplopia in investigation of relative accommodation and convergence. See relative convergence.
point of regard Usually a synonym of point of fixation. However, in some circumstances it may be a peripheral point in space upon which visual attention is directed, while the eye is looking foveally at a point of fixation. See point of fixation.
point source See point source.
visual point The point of intersection of the visual axis with the back surface of a spectacle lens (British Standard). See distance visual point; near visual point.
point zero A point on the retina of a strabismic eye which has acquired the same visual direction, under binocular conditions, as the fovea of the fixating eye.
Patient discussion about point
Q. what is the difference between tender points and trigger points. I read somewhere in the net that there are two points called tender and trigger points which are one of the symptoms of fibromyalgia. Is that true? If so what is the difference between tender points and trigger points?
Q. can Autism appears in any point in life?
Q. My aunty who is suffering from fibromyalgia feels the position of painful tender/trigger points moves. My aunty who is suffering from fibromyalgia feels the position of painful tender points /trigger points moves. The pain moves. For this reason, pain cannot be bound to specific points. Can anybody help?