I have undergone 4 different comprehensive eye exams in the last few years. All were conducted at an ophthalmology office although the actual assessment was sometimes done by technicians. This includes the totally routine eye chart reading while covering one eye and then the other, sometimes several versions of this. Often the eye chart is projected onto the wall rather than a static poster.
All 4 times they would have me cover one eye, read the chart, then cover the other eye, and read the same chart. When I read the chart with one eye, then I remember most of what the chart contains and I’m primed to recognize the symbols with the other eye, right? So my other eye is going to perform better than it would when examining the same chart because of that prior knowledge. That seems like it would significantly impair the actual assessment the test was going to make. This strikes me as something super obvious to control for by giving a new chart every time you do it.
During the last exam, I made this point, and I said “wouldn’t it make sense to show a different chart for each eye, since I can remember what this chart has?” and then the tech flipped a switch and a different eye chart came up. Apparently that was an option the whole time, they just weren’t using it.
Am I correct that this seems like a flawed procedure, if they re-use the same eye chart? Obviously your memory is going to prime recognition.
Since this is such a routine part of what they do every day, how could they not actually be changing the eye chart for each eye? Is this a violation of best practices? Are they just being lazy? This was 4 exams in 3 different offices and none of them did it right. Are most eye doctors like this? This seems like on the level of a phlebotomist forgetting to swab the area or some other routine, obvious, important thing.
I’ve felt similarly in theory, but in general it hasn’t been a problem, at least for me. I even think I remembered some the chart from my previous visit back when I was going more regularly (I had a procedure done to lower my ocular pressure, and in between multiple visits to confirm the diagnosis of the high ocular pressure and the testing to see if it had come down, I went in quite a lot and they checked my vision every time even though that wasn’t the reason I was really in there), but I was always able to legitimately determine if I could actually discern the letters and wasn’t just remembering them. For people that are inclined to cheat on such tests, it might be a problem, but they’re only cheating themselves out of the correct strength of corrective lenses.
You don’t necessarily need to fully remember a sequence for it to be helpful in priming your perception. Perception is an active process where your brain combines different information and mental tools to try to figure out what something is, and having been exposed to something in the past, even if you can’t explicitly remember it, can improve perception and recognition. You may not remember it was “AEZPJ” but you may remember “I think I remember a P in there” and it’s going to help your brain figure out that it’s a P and not an R. You may not even realize this process is happening, because once your brain decides it’s a P it sort of reinforces seeing it that way.
I understand what you’re saying, and it might be the case that I was able to discern things slightly better on the second eye than I should have, but I definitely remember the experience of “I know that’s an H from the previous test, but I can’t actually tell it’s an H with just this eye”.
In my experience, the question is really whether the first one or the second one is sharper or more in focus. And my current ophthalmologist now uses a system where the two images are shown at the same time; one on the left and the other on the right.
At my last exam, the doctor had an eye chart that had variable content. It was nice. I didn’t feel like I was reciting every chart I’d seen for the past 60 years.
I don’t think so. I’ve been spending a lot of time with ophthalmologists, due to upcoming eye surgery. Yesterday the techs varied the projected charts between eyes, as they’ve done every time. Sometimes even on the same eye, when they want me to try again on a particular line/size. I guess it’s office-specific, but mine seem keen to avoid any memorization.
A friend had enough speeding tickets to warrant a retake of his driver’s test. He’d always had an “L” on his license (corrective lenses required). He wore glasses, but occasionally drove without and worried about being caught.
Prior to his re-test he got fitted with contacts. He didn’t like wearing them, but he could tolerate them for a few hours. He told the examiner he’d had corneal surgery and had 20-20 vision. He was tested and passed, no more “L”.
Maybe it’s a case that the opthamologist would rather have an “A to A” comparison of both eyes using the same eye chart, because the possibility of the test being skewed by memory of the letters is not as strong as the possibility of the test being skewed by using different charts.
Same here. The initial eye chart has always been just one part of the testing and I figure whatever discrepancy might show up there comes out when doing the other parts (A or B? A or B?).
The only place it really matters how many rows you can read is at the division of motor vehicles.
I often say stuff like, “that looks like an ‘h’, but it’s fuzzy”, and the key part of the test is “which looks better, a or b?”
fwiw, my childhood optician said that smarter people can read further down the eyechart with the same vision – there’s a lot of post processing in vision. But again, it’s really not about how far down you can read, it’s about finding the best correction and making sure it’s good enough.
First, there is no benefit for cheating on eye exams. If I have trouble seeing as clear with one eye over the other, I’m going to mention that to my doctor.
Second, the reading of the rows isn’t about getting the precision of your prescription of your individual eyes. It’s an indicator of where the doctor should start when fine tuning between this power or this power. The doctors are practiced at getting to the correction you need for each eye.
The letters and font selected are known as the optotype and designed to be equivalently discernible at the same size while inducing a sufficient number of confusions with similar letters at low acuity. A lot of these were paper charts with fixed values - the ETDRS chart which was originally created for diabetic retinopathy but now used for general acuity. Some electronic versions scramble the order, but then there does arise an issue of creating confounds where one line is easier to identify than another even though they’re the same size/visual angle.
They also don’t just shrink the line and then stop when you can’t read it and call it “good enough.” They can repeat with a previous line to verify, and also a standard eye exam includes other measures like axis angle for testing astigmatism, if your responses for similar stimuli are not systematically similar, this may be evidence of faking good or faking bad, or misunderstanding the task, and repeats may be needed.
At the DMV? Quite frankly they don’t care much to make it an issue, you can fake your way if you really want to.