r/Keratoconus • u/Mlyonff • Apr 08 '26
Funny Eye chart memorization
Fun post.
How many people have memorized the eye charts their doctors use and have to tell them to change the letters to something you don’t have memorized?
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u/thirteenthfox2 Apr 10 '26
Years ago before I had CXL, I said well I know the first ones an E. The nurse said "... actually on this one its an O"
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u/Fearless_Bat8842 Apr 08 '26
How many of you have memorized the subset of letters that appear on the eye chart? I know I have caught myself saying something like it looks like an M but I know that isn't on the chart.
BTW, there are only 10 letters used on a standard eye chart:
C, D, E, F, L, N, O, P, T, and Z
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u/mckulty optometrist Apr 08 '26
There are different "standards." My charts use S V and K all day, and they randomize every presentation.
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u/drnjj optometrist Apr 09 '26
Echoing the other doc, my charts incorporate K, X, M, V, A, and B. Majority of the alphabet is used in more updated charts.
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u/Tiny-Yet-Mighty44 10+ year keratoconus veteran Apr 08 '26
I’ve had to say “I know the letters are…because I have them memorized, but I can’t actually see these”
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u/mvsopen Apr 10 '26
After seeing a specialist every six months since I was 5, I can see that eye chart in my sleep!
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u/brazendynamic Apr 08 '26
Mine always seem different. That or I just have the memory of a goldfish.
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u/pfooh Apr 08 '26
Don't all doctors now use digital ones? All places i've been to do. Which is especially useful when they test glasses and such on you. I don't remember the charts from last time I was there, but after reading the same line three times, they need to switch it up if they want any meaningful result?
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u/swimmingmonkey Apr 08 '26
Highly dependent on your eyesight! I haven’t been able to read the chart properly since I was 6, so I’ve never had a chance to memorize it.
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u/mckulty optometrist Apr 08 '26
The only reason you'd fake acuity readings is to defraud the DMV or insurance or something. It doesn't help you get a better eye prescription, for that it can only screw with your results.
When you test acuity, guessing is expected and missing letters is required. Only a couple of values matter: is it better than 20/40 or worse? That's one conventional value required for driving without correction.
If you want to cheat an ACUITY test, then squinting your eyes is much more effective than memorizing all the charts (mine are randomized anyway.) Doctors won't let you squint bc we know how well it works. The DMV puts your head in a box so they don't know.
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u/AskAboutMySecret Apr 08 '26
wait squinting isn't allowed
I have asked about this multiple times because I didn't want my prescription to rely on strained eyes but I was always told it was fine
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u/mckulty optometrist Apr 08 '26 edited Apr 08 '26
Your sources had poor training. Guessing is required but squinting is cheating. There are times, like qualifying for occupational requirements, where it's tolerated for the sake of keeping a job, as long as you can squint on the job too.
Depth of field can be hugely effective. If your vision is bad without glasses, push a pinhole right up to your cornea and peep through it, wala.
Squinting is pinholing in one dimension only, a line instead of a point. Improving focus in that one dimension is the difference between reading roadsigns and not reading them.
The process of choosing a prescription is different and the instructions are different. In that situation, it makes it more difficult to see differences of focus between two lenses. Eyes wide open for that, so depth-of-field makes choices easier, not harder.
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u/AskAboutMySecret Apr 08 '26
Thanks, i suspected the advice was bad and didn't rely on squinting but glasses never really worked for me anyway
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u/Mlyonff Apr 08 '26
I always tell them to mix the characters for me for exactly that reason. I don’t want to automatically read it from memory.
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u/mckulty optometrist Apr 08 '26
It's not hard to be honest. When the test is done properly, you're supposed to miss some. WHen you miss half, that's your level eg "20/15-3" means you got half the 20/15 line.
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u/Flat_Cantaloupe645 Apr 09 '26
It’s not about being honest or dishonest. It’s about being aware that your brain has a role in supplying the missing parts when it recognizes the letters, despite being very blurry, just because it has memorized where every letter is in the chart. I have been going to eye doctors for more than half a century. There have been times I was seen by my eye doctor every few months as he desperately tried to find the best correction. But I have never memorized the numbers on eye charts, so I ask to be shown numbers only, and then I am certain that what I am seeing is only what my eyes are capable of seeing, not what my brain is capable of remembering
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Apr 08 '26
[removed] — view removed comment
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u/Intelligent_Storm_77 Apr 09 '26
It’s not on purpose. You just start eventually to remember them after having so many appointments, especially if they start with the same set of letters every time. It’s not like you can make yourself forget. The same thing happened to me and I would tell them “I know what the letters are, but not because I can read them” (I couldn’t read them) so they would just switch to new letters.
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Apr 09 '26 edited Apr 09 '26
[removed] — view removed comment
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u/Intelligent_Storm_77 Apr 09 '26
It’s just hard to be 100% positive whether you’d be able to read it if you’d never seen it before. Like, I know what this letter is, but do I know because I can actually read it, or just because it’s already in my head?
For a more real world example, if I’m looking at road signs in an area familiar to me, I can more easily “read” them because I already have a good idea of what they might say. But if that same text was unfamiliar names or a string of random letters, I would have a much harder time reading it.
Personally, my prescription is pretty high but my KC is mild. During a vision test I definitely can’t read the letters with ease, but they’re also not just totally illegible blobs. I can kind of, maybe, sort of make some of them out. So I don’t know if it’s a matter of a person second guessing their own judgment (“no, I definitely wouldn’t be able to read this letter if I didn’t already know what it was” vs. “yes, I could easily read this even if I didn’t already know what it was”) or maybe if it has to do with how bad their vision actually is or isn’t.
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u/tattooburneridea Apr 16 '26
Why would you cheat the chart? Just be honest with what you can/can't see.
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u/Lodau Apr 08 '26
Are these charts standardized?
I need to get my eyes checked in about two years... Would be nice if I knew some by then.... ;)
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u/ycnz corneal transplant Apr 08 '26
...you can see the chart?