Author Topic: Snellen Chart - don't have 20 feet to stand  (Read 1021 times)

Offline graeme

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Snellen Chart - don't have 20 feet to stand
« on: April 29, 2014, 05:16:21 PM »
I tried setting up a snellen. I don't have 20 feet to stand. I have 19 at the very longest. When I tried at 19, my left eye couldn't read any lines. My right eye could read 20/200. When I approached to 10 feet, my right eye could read 10/70. My left eye still couldn't read.

That was in my hallway, with no windows. I then tried putting the snellen on my living room window, with bright light. I could only stand 10 feet away.

My right eye was 10/50 or 10/40. My left eye was 10/200. My prescription is -3.5/-2.

1. Is it ok to measure the snellen from 10ft?
2. Do my measurements (10/200 and 10/50) match my prescription? My snellen readings seem really weak.

Offline OtisBrown

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Re: Snellen Chart - don't have 20 feet to stand
« Reply #1 on: April 30, 2014, 06:55:01 AM »
Hi,

Answers:

1. Is it ok to measure the snellen from 10ft?

YES!

2. Do my measurements (10/200 and 10/50) match my prescription? My snellen readings seem really weak.

Probably.  But I do not know what you mean, "My Snellen readings seem really weak."  Could you explain what you mean?

Thanks

Offline graeme

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Re: Snellen Chart - don't have 20 feet to stand
« Reply #2 on: April 30, 2014, 01:16:38 PM »
What I meant was: my left eye can't even read the Snellen at 20 ft. It's -3.5 at the optometrist. I didn't realize this was worse than 20/200.

But now that I look at this snellen conversion chart, I see that's roughly correct.

http://forums.studentdoctor.net/threads/diopters-vs-20-somthing.202129/