They say that you should get your eyes checked every two years but if haven’t had the chance to see a doctor all this time, you can test your vision on your computer as well. Of course these self eye tests are no substitute for visiting your doctor but if you follow the steps well, you may get some idea about how good (or bad) your vision is.
Most of us are familiar with the Snellen Chart that has rows of alphabets of different sizes – you read these letters from a distance, usually twenty feet, and the smallest row that you can recognize accurately indicates whether you have normal vision or not.
The various eye testing tools that are available online make use of the same Snellen chart.
The Snellen eye chart is the eye testing chart used by eye care professionals to measure visual acuity, or how well a patient can see without glasses or contacts. Dr. Hermann Snellen developed the eye chart in 1862.
When testing for visual acuity, the patient covers one eye and reads aloud the letters on the chart, beginning at the top and moving toward the bottom. The smallest row of letters that the patient reads accurately determines visual acuity in the uncovered eye. The test is repeated with the other eye, and then with both eyes together.1 Visual acuity is sometimes expressed as 20/20, or a similar number, meaning the smallest letters accurately read on the chart.
The results of your acuity exam (chart reading) will determine the quality of your eyesight. Your vision results (acuity) will be expressed as a fraction. Fractions are shown to the left of each row and identify how well you can see. If you could read clearly to the fifth line, for example, your vision will be expressed as have 20/40 vision; if you could read clearly to the seventh line, your vision will be expressed as 20/25.
