The Amsler grid, used since 1945, is a grid of horizontal and vertical lines used to monitor a person's central visual field. The grid was developed by Marc Amsler, a Swiss ophthalmologist. It is a diagnostic tool that aids in the detection of visual disturbances caused by changes in the retina, particularly the macula (e.g. macular degeneration, Epiretinal membrane), as well as the optic nerve and the visual pathway to the brain. Amsler grid usually help detecting defects in central 20 degrees of the visual field. In the test, the person looks with each eye separately at the small dot in the center of the grid. Patients with macular disease may see wavy lines or some lines may be missing. Amsler grids are supplied by ophthalmologists, optometrists or from web sites, and may be used to test one's vision at home. The original Amsler grid was black and white. A color version with a blue and yellow grid is more sensitive and can be used to test for a wide variety of visual pathway abnormalities, including those associated with the retina, the optic nerve, and the pituitary gland. History In 1869, Jacob Hermann Knapp described scotoma and metamorphopsia in traumatic maculopathy with choroidal rupture using horizontal lines. Similarly in 1874, Richard Forster demonstrated metamorphopsia using a square grid. Swiss ophthalmologist Marc Amsler described the Amsler grid in the year 1945. It was the first functional test proposed to evaluate metamorphopsia. He may got the idea of the grid from Edmund Landolt, who used a similar small card with a grid pattern to be kept in the center of the visual field testing instrument perimeter. Clinical significance Amsler grid can be used in detecting central visual field defects in following conditions: Age-related macular degeneration: The grid will help detecting the progression of AMD from dry form to wet form. Chance of metamorphopsia is more in wet AMD compared to dry form. Choroidal neovascular membranes: Choroidal neovascular membranes cause scotoma and metamorphopsia. It may be associated with many diseases like macular degeneration, POHS, myopic macular degeneration, trauma etc. Central serous chorioretinopathy: CSCR Causes round or oval scotoma. Macular pucker: Macular pucker also known as an epiretinal membrane cause metamorphopsia and distortions in central field of vision. Cystoid macular edema: Due to macular edema, micropsia may occur. Glaucoma: Amsler grid is useful in detecting central field defects in moderate to severe glaucoma. Macular