Macular degeneration charts, such as the Amsler grid, help diagnose eye diseases and issues by identifying specific regions of a person's visual field where visual anomalies are occurring. Changes in the size or severity of perceived distortions on the chart help to define disease progression, according to Amslergrid.org.
The Amsler grid is chart of horizontal and vertical parallel lines arranged in a regular square grid. A small circle indicates the center of the grid. A viewer of the chart visually fixates on the center circle and should contact an eye doctor if he notices any blind spots, broken lines or blurry portions of the grid, states Amslergrid.org.
The chart viewer wears any corrective lenses or glasses normally used for reading, including the lower portion of bifocal lenses, states the American Macular Degeneration Foundation. The Amsler chart is affixed to a wall and viewed at a comfortable reading distance, usually 12 to 14 inches. The viewer records a baseline pattern of observed visual anomalies on the first day the chart is used by marking areas of the chart with a pencil. Subsequently, the viewer should observe the chart each day from the same distance. New areas of vision problems or enlargement of baseline problem areas indicates worsening vision and an eye examination may be warranted.