 My
son is 5 years old and has just had his first school eyesight test.
We
have been advised to take him to see an optician - which of course we will do
but I just want to check what the following means.
The school test said
that on the Snellen scale he is 6/6 (20/20) in his left eye and 6/9 (20/30) in
his right eye. (This is in metric)
Can someone explain what this means
and if it is anything to seriously worry
about.
Herman Snellen, a Dutch ophthalmologist, designed the first eye chart,
which measures visual acuity. Referred to as the Snellen Chart, it was developed
in 1862 and is still used today. He set the baseline of measurement at 20
feet, the approximate distance at which light rays entering the eye are parallel
and do not require our eyes to bend the rays to focus them upon the retina.
Snellen
set the standard of 20/20 vision to represent "normal sight," or what a person
with normal vision could see at a distance of 20 feet. (Weber, Humphrey, and Silver,
1997)
This means that a person with 20/40 vision must be 20 feet away to
read what he or she should be able to read at 40 feet; a person with 20/85 vision
must be 20 feet away to read what he or she should be able to read at 85 feet
away, and so on.
This standard does not measure visual acuity at close
distances. Similar charts were devised with smaller letters to read at close range
for the measurement of near vision. Snellen
20/10
20/15
20/20
20/25
20/30
20/40
20/50
20/100
20/200 | Metric 6/3
6/4.5
6/6
6/7.5
6/9
6/12
6/15
6/30
6/60 |
A
Snellen Chart is included in the Rebuild Your Vision program so that you
can measure your vision as it improves. We've also included a log for you to record
your progress.
Seven other optical tools and charts are also included in
the package.
The charts that are included have a special glare-free laminate
to ensure your ability to perform the exercises under all lighting conditions.
Each one is used to perform the different eye exercises and vision improvement
techniques.
You can get the program delivered to your front door within
two to three days and start the exercises within about 10-15 minutes
from when
you open the package. You'll be amazed at how easily and quickly your vision improves.
Take
the first step to improving your vision -- for life. See for yourself at http://www.Experts-At.com/Rebuild-Your-Vision.html
All
the best, |