Amsler Grid

A grid pattern for testing central vision

Overview

The Amsler grid is a square grid of evenly spaced horizontal and vertical lines with a central fixation dot, used to test the central visual field, the area served by the macula. It was introduced by the Swiss ophthalmologist Marc Amsler in the 1940s. When viewed with one eye, the grid can reveal metamorphopsia, in which straight lines appear wavy or bent, and scotomas, areas where lines appear missing or blurred. These signs are characteristic of macular disorders such as age related macular degeneration, particularly conversion to the wet form, as well as macular edema, epiretinal membranes, central serous chorioretinopathy, and macular holes. In clinical practice it serves as a simple, inexpensive screening and monitoring tool and is often provided to people with macular disease, although its sensitivity for detecting new disease is limited, partly because the brain can fill in missing areas of the image. Variants include grids with different colors and patterns, and digital tests and preferential hyperacuity perimetry devices have been developed to improve the detection of macular changes.