An Amsler Grid is used to monitor the central 30 degrees of visual field for signs of distortion or visual abnormality that may signal the onset of wet macular degeneration. It is important to test each eye independently by covering one eye and then the other when using the Amsler Grid. With the Grid held reading distance away, look at the central dot and make sure all of the lines are straight and that the entire grid can be visualized. If straight lines become wavy or distorted, or a portion of the grid is missing, then you should call your ophthalmologist or retina specialist for an immediate evaluation. These changes will come on suddenly, even overnight, and merit urgent evaluation in someone with a known history of dry AMD.