20/20 vision explained

Many of us yearn for perfect vision, to be able to see without having to wear glasses or contact lenses, or even undergo surgery, but few are lucky enough to have it. But just what does it mean when someone has 20/20 vision?

Perfect vision

If you are told you have 20/20 vision, what this actually means is that you have what is considered to be normal vision. The numbers refer to visual acuity measurements called Snellen fractions, after Herman Snellen, who developed the measurement system back in 1862. In the Snellen system, the testing distance between the patient and the eye test chart is usually 20 feet, hence the first part of the fraction. At this distance, if the patient can clearly see the letters written on one of the smaller lines located near the bottom of the eye test chart, but nothing below the line, then the patient is classed as having 20/20 vision or visual acuity.


Over the last decade or so, it seems that the number of people with 20/20 vision is decreasing, and this has been attributed to an increase in computer use, or in fact, any use of a device that has a digital screen. Often, we believe that worsening eyesight is just a factor in ageing, but it is true that eye exercises can help towards retaining good visual acuity. There is a theory that wearing glasses or contact lenses actually weaken eyes and makes them reliant on these aids. Of course, some people have unavoidably bad eyesight and need corrective lenses to achieve 20/20, normal vision. If you are one such person but hate having to wear corrective aids, then you could consider having laser eye surgery to achieve 20/20 vision. This is now a routine procedure with super-fast recovery times.

Eye exercises are easy to perform daily and take only a few minutes. One of the side effects of computer use is that we do not blink as often as we need to, which dries the eyes. So, engage in rapid blinking, every four seconds for two minutes, then slow blinking every 30 seconds for two minutes, and repeat this three times. This will rest your eyes. A great exercise for lazy eyes, that will improve your eye muscles and their flexibility, is to visualize an enormous figure of eight that is sited about ten feet in front of you. Then turn it on its side and begin to trace this imaginary figure with your eyes, one way for about three minutes, then the other way for the same time. To strengthen your eye muscles, hold up your thumb about ten inches from your nose. Focus on your thumb then shift your gaze to a point at least ten feet beyond it, and take a breath. Then look back at your thumb and repeat for about three minutes.

Glasses, contact lenses and laser eye surgery are all means of acquiring normal, 20/20 vision, which is desired by many, but it is also possible to improve your eyesight by exercising your eyes, just as you would your body, on a daily basis.

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