How clear is your vision (Visual Acuity)

 A lot of people tend to take the fact that they see for granted.   

They go about performing daily activities without a minute’s pause as to the blessings of good eyesight.  But then, how clearly do you see?  Lets pause a while.  You may see clearly enough to perform your daily activities comfortably; still, how acute is your vision? 

Visual acuity refers to the ability of the visual system to resolve detail. 

Whenever an eye examination is done, one of the first tests carried out is the visual acuity test. This is a form of measuring the ability of the visual system to resolve detail, or put in another way, measuring how acute vision is. This is done over a standard test distance of 20 feet or its equivalent of 6 meters.

The patient is asked to sit at a distance of 20 feet(6 meters) away from a test chart which has letters, objects or figures referred to as optotypes, presented on it in varying degrees of sizes. Visual acuity measurements are normally written in fraction form where the numerator indicates the test distance and the denominator indicates the angle of resolution i.e. the distance the eye can see the optotypes on a certain line of the eye chart.

The term 20/20 or 6/6 states a reference standard for acuity in vision. Normal visual acuity in healthy eyes is averagely one or two lines better i.e. 20/15 or 6/4.5.  So imagine having a visual acuity of 20/40 (6/12), it means the smallest letter you can see at 20 feet (6 meters) can be seen by the normal eye at 40 feet (12meters).

Everyone should have good vision but sadly, not everyone does. A number of factors could cause a reduced visual acuity. Some of these factors could be physiological (refractive errors), pathological (eye diseases) or physical (eye trauma) but with visual aids and/or good eye treatments, a 20/20 visual acuity can be achieved.

In most cases, refractive errors are easily remedied by eyeglasses. Eyeglasses enable children and adults to see more clearly, improving their potential for academic success as well as productivity at work and alleviating the social and behavioral problems that often accompany the frustration of not being able to see properly.

 

 Poor vision may even lead a child to drop out of school as a result of chronically poor academic performance. Adults whose childhood visual impairment denied them the opportunity to obtain core academic skills are at a disadvantage in seeking employment, achieving economic independence and making valuable contributions to their community.

Reasons behind carrying out a visual acuity test are:

• To check the presence or absence of ocular abnormalities
• To aid the eye doctor in refraction and verification of optimal correction of refractive errors
• To monitor the effect of a disease and/or its treatment
• To evaluate or estimate the ability of individuals to perform certain tasks (e.g. drivers screening for license).

The test when carried out causes no discomfort and there are no risks. 

 So back to the question – How clear is your vision?

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