Amsler grid
grid [grid]
Etymology: Marc Amsler, Swiss ophthalmologist, 1891-1968
a checkerboard grid of intersecting dark horizontal and vertical lines with one dark spot in the middle. To discover a visual field defect, the person simply covers or closes one eye and looks at the spot with the other. A visual field defect is perceived as a defect, distortion, blank, or other fault in the grid. The person may record the defects directly on a paper copy of the grid that may be kept as a permanent record. The Amsler grid is used in testing for macular degeneration.
grid [grid]
1. a grating.
2. in radiology, a device consisting essentially of a series of narrow lead strips closely spaced on their edges and separated by spacers of low density material; used to reduce the amount of scattered radiation reaching the x-ray film.
3. a chart with horizontal and perpendicular lines for plotting curves.
Amsler grid see Amsler charts.
baby grid a direct-reading chart on infant growth.
cross-hatched grid two linear grids that are superimposed at right angles to each other, used for maximal scatter cleanup.
Cross-hatched grids are fabricated by sandwiching two linear grids together so that their grid strips are perpendicular. From Bushong, 2001.
grid cutoff differences in radiographic intensity that are caused by improper focusing of the lead lines of a grid.
focused grid a linear grid in which all of the lead strips are aligned in a tilted fashion toward a centering point.
linear grid a grid designed to permit the passage of the primary beam by having lead lines aligned in the same direction separated by radiolucent interspacing material. There are two types, parallel and focused.
Wetzel grid a direct-reading chart for evaluating physical fitness in terms of body build, developmental level, and basal metabolism.
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