Perhaps as you've gotten a little older, you’ve noticed changes in your vision. Perhaps your family has a history of eye problems. Or maybe your children have shown signs of vision problems, and you don't know if they need an optometrist's help yet.
1. Distance Vision, Myopia, or Hyperopia Test You'll recognize this test because of its iconic chart. The chart (called a Snellen eye chart) features eleven or so rows of letters in increasingly smaller sizes. To take this test, follow the steps below: Print the chart off a reputable optometrist's website, and follow those printing instructions. Typically, you'll need a chart about 28 cm by 14 cm (11 in. by 5.5. inch.), but this depends on the letter's relative size. Consider purchasing a chart if you don't think you can print the right dimensions. Hang the chart at eye level in a well-lit room with a little more than 3 m (10 ft.) of space. Stand about 3 m (10 ft.) away from the chart and cover one eye. Read the letters on each row until you reach characters you can't make out. Write down the line number, then repeat the test again by covering your other eye. To pass this test, you should have the ability to read the row fourth from the bottom. Snellen charts vary, and some mark the 20/20 vision row with a bold line. But if yours doesn't, assume that the fourth-to-last row represents the ideal. If you can read smaller lines, you have better than ideal vision. 2. Near Vision or Presbyopia Test Sometimes your ability to read fine print decreases with age, even if you hold text close to your face. Print off a Snellen chart (or a block of small text) on a normal-sized piece of paper and take the following steps: Hold the chart 35 cm (14 in.) away from your face. Cover one eye. Read the chart until the letters become indistinguishable. Make note of the line. Repeat the process with your other eye. Again, you should have the ability to read to the 20/20 line. If you can't, then you probably have presbyopia, or an age-related vision problem that decreases your eyes' focus. Glasses or contacts will help you overcome this problem. 3. Astigmatism Test The Snellen eye chart also reveals astigmatism, or an abnormality in your cornea's curvature. Astigmatism often accompanies myopia (nearsightedness) or hyperopia (farsightedness), and it blurs your vision further. However, to determine that you have astigmatism and not these other conditions, give yourself this additional test: Take a piece of paper and draw a series of lines radiating out from a central point in a half circle. Make sure each line looks perfectly black, and make them all the same length if possible. Cover one eye and look at the lines. Document which ones seem greyer, if any. Don't forget to document which eye sees them greyer. The lines won't appear greyer if you don't have astigmatism. If you do see grey lines, then your corneas refract light incorrectly, and you need to see an optometrist for corrections. 4. Ishihara/Colour Blindness Test You probably know whether or not you have colour blindness. However, your children may have it and not know. If you suspect they have trouble differentiating between colours, have them take the Ishihara test online. This test has them take the following steps: They look at a series of colour plates containing numbers or patterns. Have your children write down or draw the shapes they see. Some colour plates test for colour deficiency instead of colour blindness. Eyes with colour deficiency may see different numbers than those with normal eyes. If the test reveals your children have colour blindness or deficiencies, take them to your optometrist for further testing. 5. Amsler Grid/Macular Degeneration Test Macular degeneration blurs your vision, distorts the way you perceive straight lines, and creates blind spots. Your brain will sometimes even correct these abnormalities for you, so you may not realize you have them. However, macular degeneration can lead to blindness if left untreated, so use the following test to ensure you don't have it: Print off an Amsler grid. You don’t need a large one. It should look like any other grid with a dot in the middle of it. Hold the grid 35 cm (14 in.) away from your face and cover one eye. Look at the centre dot and nothing else. You'll see the rest of the grid in your peripheral vision. Note any abnormalities with a pencil and switch eyes. The lines should appear perfectly straight and unbroken. If you see wavy lines or missing spots then you may have macular degeneration. Meet with your optometrist for further tests and treatment. Again, these tests do not replace a regular eye exam, but they can help you pinpoint problems with your vision. If any of these tests gave you results you didn't expect, contact your optometrist to learn more.