The best way to take care of your eyes, monitor eye health, and detect potential vision problems early—when they’re more easily treated—is to make annual appointments with your eye doctor.
Home vision tests, however, can serve as useful tools for testing your eyes in between visits. Abnormal results from these tests can help you discover changes that require medical attention.
Understanding Macular Degeneration
The Amsler Grid test helps detect vision problems related to macular degeneration. This incurable disease makes it difficult for you to see clearly in the middle of your field of vision. According to the American Macular Degeneration Foundation, macular degeneration is the leading cause of blindness in people over the age of 55 and affects more than 10 million Americans (AMDF).
A patient can suffer from one of two types of macular degeneration:
- Dry macular degeneration, in which the central portion of the retina, called the macula, deteriorates. This is the more common type.
- Wet macular degeneration, in which leaky blood vessels at the back of the eye cause swelling and changes in vision. This type is rarer.
Symptoms of macular degeneration include:
- difficulty recognizing faces
- need for increasingly bright light
- haziness in overall vision
- blurred or blind spot in the center of your vision
The Amsler Grid Test
The Amsler Grid is a simple test that will help you discover changes that may indicate a problem with macular degeneration. It looks like a piece of standard graph paper with a black dot in the middle. (You can find a copy to print out at AMD.org) There are also additional forms of the test that further identify issues with vision, such as a graph with a large "X" through it or a black graph with white lines.
To check your vision, wear the glasses or contacts you normally wear when reading, then view the chart at arm’s length (about 18 inches) while covering or closing one eye. Focus on the center dot, while being aware of the surrounding grid. If any of the lines are bent or appear distorted, or if there seems to be a certain area of the graph that is blurry or missing, this may be evidence of a swelling in your retina.
If you notice these issues, see your eye doctor right away. Macular degeneration cannot be cured, but early detection can lead to treatments that limit vision damage.
Distance and Near Vision Tests
You can also use home vision tests to check your nearsightedness and farsightedness. To test for both conditions, you can use the standard eye chart called the "Snellen Eye Chart." (You can find a printable version of this chart here.)
For this test, stand 20 feet away from the chart. Then, cover one eye and read the lowest line you can see clearly. Cover the other eye and repeat.
The lowest line you can read indicates your visual acuity in that eye. To get your number, start by standing 20 feet away, then add the number that is printed next to the lowest line you’re able to read. For example, if you can read the second line up from the bottom with your right eye, your vision is 20/20 in that eye.
A similar near vision testing card works the same way. You simply hold the chart 16 inches away, then cover one eye and read the lowest line you can. Your visual acuity is calculated the same way.
Normal results for both tests would be 20/20 in each eye. If your results are higher than that, check with your eye doctor for methods to improve your vision.
Most people who have trouble discerning colors aren’t necessarily "color-blind." They have a color vision deficiency that makes it hard to distinguish certain colors or shades of the same color. For example, distinguishing red from green is one of the most common difficulties.
This is another condition that you can test at home. The Ishihara test for color blindness shows several multi-colored plates with numbers or lines on them. (You can find a copy here.) Simply identify the numbers or trace the lines. Difficulty in reading these tests will indicate areas of color vision deficiency.
Tests for Other Conditions
Some online sites offer at-home tests for other conditions such as glaucoma, astigmatism, and presbyopia (loss of elasticity in the lens of the eye). However, for these conditions and the overall health of your eyes, it’s best to be examined by your doctor.