The Amsler grid is a tool which is used to assess vision for the purpose of checking for and monitoring changes. It can be used during an eye exam in a doctor's office, and it can also be used at home as part of a self-care regimen which is designed to help someone stay alert to changes in her or his vision. Many eye doctors are happy to provide their patients with a grid to use at home, and people can also print out grids from websites which provide information about vision issues.
The grid consists of a series of black lines on a white background, with a white or black dot in the middle to provide a point for the user to focus on. When someone's vision is tested with an Amsler grid, one eye is tested at a time, with the other eye being covered during the test. The patient looks at the grid, focusing on the center dot, and reports any abnormalities in the grid.
In a person with healthy vision, the Amsler grid should appear crisp and undistorted. If someone has vision damage such as macular degeneration, areas of the grid may be missing, wavery, or otherwise disturbed. Information about the location of the damage can be gathered from the patient's report about which area of the grid appears abnormal.
When a doctor suspects that vision damage may be occurring or that a patient is at risk for a condition such as macular degeneration, an Amsler grid may be used during an eye exam to test the patient's vision. Patients can also specifically request an assessment for vision damage if they have been experiencing vision problems. It is important to be as descriptive as possible. Rather than just saying “some of the grid looks funny,” the patient should indicate where distortions are occurring and describe them with language like “this area is blank” or “these lines are distorted.”
At home, an Amsler grid can be used to check for vision changes, but it does not replace regular eye exams. If someone notices changes in vision as a result of self assessment, it is important to see a doctor for a thorough workup and discussion of the implications of the vision changes. Patients should never be shy about calling a doctor to report vision problems; early intervention with vision issues increases the likelihood of a positive outcome, and a doctor would rather catch a situation early than see a patient too late because the patient was worried about being a bother.