How many degrees of central vision does an Amsler grid measure?

The Amsler grid is primarily used to assess central vision and is particularly useful for detecting visual distortions or defects that may indicate macular degeneration or other retinal issues. The grid covers an area of approximately 20 degrees of central vision, which is crucial for evaluating how well a patient perceives straight lines and central details within that visual field.

This specific measurement is important because it enables healthcare professionals to identify potential problems within the central vision, where detailed visual tasks—such as reading and recognizing faces—are performed. By using the Amsler grid, patients look at a central point and report any distortions or missing areas, highlighting issues in their central vision that may need further investigation.

The other options represent areas of visual measurement that do not correspond to what the Amsler grid is designed to assess, as the grid functions specifically within the 20-degree range to focus on detecting subtle changes in central retinal function.