Sunday, 20 January 2008

Eye test charts

On the evening of 12th January, my sister, her bf, my grandparents and I (five of us) went to a glasses store. My sis and her bf (S) wanted to get new glasses. They spent ages choosing the right frames. In the end she got a nice pair of half frame Byblos ones and S got a frameless one. I decided to get an eye test done as it had been a while since I had done one, even though I knew nothing was wrong.

Now, I hope it doesn't sound like I'm bragging but I have very good vision. Actually maybe I am bragging but I don't care. I am very proud because it is one of the few things on my body that work really well, so well, probably better than 90% of the population. When my sister first got glasses around the start of high school the optometrist also tested and told me back then (when I was probably 15 or so) that my eyes would only deteriorate due to old age, around the age of 40, exactly the same as my mother who also had perfect vision until she hit her 40s and became long-sighted.

Anyway, at this little optical shop in Kaohsiung the guy who tested me told me that if I was a teenage boy in Taiwan they'd take me to become a professional sniper shooter! hahaha. Unfortunately I lack the 'hand' part of 'hand-eye coordination' LOL. I did a test where there were 4 lines of text which got increasingly smaller. The first line was marked 0.9, then 1.0, 1.2 and 1.5. Apparently 1.0 is normal or average, 0.9 is you have slight problems, and 1.2 and 1.5 your eyes are above average. I had no problems reading the 4 numbers on the 1.2 line and could read 3 of the 4 letters on the 1.5 line and actually got the 4th number correct too although I was tossing up wither it was an '8' or a '9'. I went online to find out what this chart was called but I couldn't really find any information on it. It is like a cut down version of the "Snellen chart.".

The guy also told me that my eyes would begin deteriorating around the age of 38-39. I was like WTF?! That's only a few years away! Geez. He said something about it being 'fair'.. how those who have worn glasses since they were young peter off around the 20's and don't really get worse, whereas those of us with perfect vision hit a point in our life and then progressively get worse. Great! Which is worse? Hmm...

I remember telling people years ago that I had better than 20-20 vision and that I have no problems seeing things up close OR far away in the distance. Some people scoffed and told me this is impossible. Actually 20-20 is not perfect vision, it is just average vision. It is explained here.

In the Snellen fraction 20/20, the first number represents the test distance, 20 feet. The second number represents the distance that the average eye can see the letters on a certain line of the eye chart. So, 20/20 means that the eye being tested can read the small size letter that the average person can see from 20 feet away. If a person sees 20/40, at 20 feet from the chart that person can read letters that an average person could read from 40 feet away.

As you can see, 20/20 vision is not perfect vision; it is average vision. Examples of better than average vision would include 20/15 and 20/10."

Here is a better, longer explanation

So according to that I probably have 20/10 vision. Well there is nothing I can do to prevent my eyesight getting worse (other than stopping time) so I guess I'll enjoy it while it lasts and when I finally need glasses I think I already know what type I'm going to get (as I tried on a few pairs myself in that shop for fun!) :)

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