If you have dry age-related macular degeneration (AMD), it is important to monitor your vision with an Amsler grid. The grid will help you detect the progression of dry AMD to the wet form of the disease at an early, treatable stage.
The grid looks like a piece of graph paper with a small dot in the center. If you wear glasses to read, put them on and hold the grid at a distance that allows you to get most of the lines in focus; it will probably be about the same as book reading distance. Cover or close one eye so that you are testing only one eye at a time. This is important; if you use it with both eyes open, the good eye can compensate for an eye with more advanced AMD, and you won’t notice any abnormalities.
An eye without AMD will usually see all the lines as straight and present. In contrast, an eye with AMD will often see some of the lines as curved or even blocked out by a gray, white or black region. This is caused by cell disruption underneath the macula or, in some cases, fluid that accumulates within or under the retina making straight lines look curved. Sometimes the fluid interferes with retinal function enough to cause a gray, white, black, or red “blind spot” in or near the center of the visual field.
The good news is that the fluid, caused by new leaky blood vessels in the retina, can often be dried up with treatment. If an eye with wet AMD goes untreated for a few months or longer, it can begin to develop retinal scarring. This scarring can lead to irreversible vision loss in parts of the visual field, so it is best to monitor your vision at home at least once a week with the grid, and call our office if you notice a change. Many patients place the Amsler grid on their refrigerator to help them remember. What constitutes a change? Take a look at the grid shortly after the exam. That’s your baseline. There may be a little waviness of the lines in a few places due to large “drusen,” semi-solid deposits that form under the retina in AMD. Then, if you check again at a later point and think the area of waviness has increased or a new area has appeared, or you have a new “blind spot,” it’s time to call our office.
Even without a grid, you may notice changes in your vision that should prompt a call:
- reading becomes more difficult;
- straight lines look curved (a door frame, for example);
- it becomes harder to see or recognize faces; or computer and TV images are more challenging to see.
- Hold the chart at a comfortable reading distance (generally, about 12-14 inches away). Wear your reading glasses if you normally use them.
- Cover one eye and focus on the black dot in the middle of the grid.
- Cover the other eye and repeat the test. If the lines appear to be wavy, dim, irregular or fuzzy, schedule an eye exam immediately.