Checking Your Eye Health

Eye Tests

There are a number of simple tests that can be performed in the comfort of your home to help you to identify potential vision problems that demand professional attention. However, care must be taken when interpreting self-test results, as these tests are not designed to pick up all problems, e.g. blind spots, peripheral vision issues, intra-ocular pressure, etc. Please remember that these tests are not a substitute for regular dilated eye exams conducted by your Eye Care Professional.

The Amsler Grid

This is a test for macular degeneration. You may use it to monitor your vision between visits to your ECP. The test consists of a grid of squares. Wearing your normal corrective lenses you test each eye one at a time. With one eye covered and the grid at arm’s length from you, look at the centre of the grid. If your eye is functioning properly, you should be able to see the centre white dot and the four corners and sides of the grid. The lines should appear to be straight and continuous from top to bottom and side to side. Any or worsening distortion in the grid should be discussed with your ECP.

It is worth noting that reading glasses may interfere with the grid. If you wear glasses consult with your ECP to establish a baseline view of the Amsler Grid against which any changes and deterioration may be measured.

The Ishihara Test

This is a colour perception test for red-green colour deficiencies. The test consists of a number of coloured plates, called Ishihara plates, each of which contains a circle of dots appearing randomized in colour and size. Within the pattern are dots which form a number or shape clearly visible to those with normal colour vision, and invisible or difficult to see to those with a red-green colour vision defect. Other plates are intentionally designed to reveal numbers or shapes only to those with a red/green colour vision deficiency, and to be invisible to those with normal red/green colour vision.

Visual Acuity Test

Typically performed using a standardized Snellen chart, this is an eye exam that checks how well you see the details of a letter or symbol from a specific distance. Visual acuity refers to the ability to discern the shapes and details of the things you see. You may need an eye exam if you feel you’re experiencing a vision problem or your vision has changed. Children frequently take visual acuity tests. Early testing and detection of vision problems can prevent issues from getting worse. Optometrists, driver’s license bureaus, and many other organizations use this test to check your ability to see. Visual acuity is expressed as a fraction: having 20/20 vision means that your visual acuity at 20 feet away from an object is normal. A person with 20/40 vision must be 20 feet away to see an object that people can normally see from 40 feet away.