What follows is neither medical advice (heh, as if), or “prescription” advice, or anything otherwise mainstream sanctioned or licensed. As usual, we’re discussing actual biological realities of a 16th century (simply focal plane changing) invention.
Don’t monkey with lenses unless you understand them, don’t drive without adequate correction, consult a friendly optometrist.
So much gold in the forum, we have to bring some of it to the blog, at least sometimes. I highly recommend browsing (if you have access), you’ll find brilliant students framing their own 20/20 gains with detailed insights, outside research, and great questions.
So here is my pragmatic question: I have a test lens kit. What is the best way to measure astigmatism with it?
The last time I saw an optometrist was a disaster. She didn’t offer “no change” as an option when asking me which lens was better so I just decided to go with my intuition and make wild guesses when I could actually perceive no difference. I didn’t realize until it was all over that she was testing me for cylinder as well as spherical and I went from never having no astigmatism to having it. One thing that threw me was that all I ever was shown on the projected (with mirror) chart were Snellen-like letters.
When I have looked online for how to do cross-cyl refraction, I saw a lot of useful info but this seemed the most practicable:
Yet my optometrist seemed to have diagnosed me as astigmatic with nothing more than a Snellen-like chart. So, should I print out (or buy) one of those radiating-lines-type astigmatism charts, or just use my Snellen, or do something else in order to test to see if I really am astigmatic with my trial frame and lens kit? And, if the answer is to use those radiating-line charts, do they really work from a distance of 20 feet? Thanks.
Projected eye charts are even more a farce than the printed variety (compare your results on one vs. the other, marvel at how big the gap is). Optometrist refusing to be transparent about the test, ridiculous. Astigmatism “diagnosis” based on above, mind numbingly irresponsible.
Of course Michael knows better than to believe he suddenly developed a new vision condition (astigmatism).
In the forum I tend to take more liberties than here in the blog, here’s what I suggest for Michael:
I tend to be hard on astigmatism (see today’s blog posts for the usual line I take on it).
Those optometrists make me a bit nauseous. Here’s what I would do: If you have directional blur, if you step down astigmatism correction (not you since you never had any, obviously – but others reading) and you get double vision you can’t fuse, if you get headaches after stepping down astigmatism, if there is directional blur specifically that prevents you from reading a line on the Snellen –> put back part of the astigmatism correction (in particular for distance, you need much less of it for close-up, in most cases).
An autorefractor is mostly good for kicking down a hallway, see how far you can smash it. I used to own three and we did all sorts of fun tests with a whole lot of people, and the things are as good as a magic eightball (remember those? the 80’s?)
Astigmatism also happens (measurably), randomly short term. Some speculate that your circular focusing muscle might not always work perfectly uniformly, and various other theories abound. Again though, the question is whether you get distinct directional blur that prevents you from either a) fusing double vision or b) reading a line on the Snellen, persistently over the course of at least a week or two.
No? Then just practice the most cat-like disinterested yawn as automatic reflex for whenever you hear an optometrist yammer on about astigmatism. ?
If you enjoy blunt real-talk from your darling host, I recommend the forum over the blog, for that extra dose.
Note that Michael a) knows what he’s doing and b) didn’t have astigmatism until the largely rigged and unquestionably unscientific lens-selling optometrist consult. If you have astigmatism (especially over one diopter), don’t just go throwing that out. As I always say, learn first, don’t monkey with things unless you fully understand their effects.
Then Toshiki who started the thread (it’s pretty long, take a read at it if you’re into the astigmatism topic), is back with a status update:
Just a quick (if I don’t get too wordy again) update on my (super-happy subjective) status:
I’ve been outside on the bicycle with my son in the trailer a lot during the last two/three weeks. Thus, I haven’t gotten around doing quantifiable active focus (focus on license plates and counting the steps from the point at which I can make out the letters) during this time. I also didn’t pay attention to when the sun sets. When I went outside today at 20:30 with the intent of doing active focus, I had to find that the sun had already set and it was pretty dark (my phone confirmed: 200 lux…). Reading plates not being possible (or rather very frustrating as I tend to get very low numbers in this light, as probably also a non-myopic person would get) I just looked around and allowed for some organic active focus. Pretty amazing results, but I should probably start earlier.
In the morning, we went outside to a huge playground and I often had to look for him at a distance of 20 meters or more in a crowd of quite a few children – after a while that was no problem at all anymore. Someone inspired him to go for a nearby snack bar with a huge outdoor section covered by roof (of course designed to attract children: no doors, readily accessible). With zero artificial lighting it was pretty dark there (especially since it was a cloudy morning threatening to rain any minute) – I’d say 50 lux at most. Following him there, I realized that I could read a sign with the menu from six meters away with zero effort. I wanted to scream “Wow, I can read that!”, but kept myself from that – I’m weird enough as it stands. Instead I covered my dominant eye confirming my amazement: reading it was almost impossible with the -0.75 eye… The way home was amazing too with lots of clarity in spite of wearing sunglasses.
Anyway, 200 lux in the evening was even cooler. Reading street signs from the other side of the street with zero effort was soo cool (again confirmed by covering the right eye with which I had serious trouble making sense of the sign). Went into a grocery store. Coming back out (now less than 5 lux), the real-time time table of the nearby tram station looked at me – razor-sharp letters, not only for the current time, but also for the destinations and departure times (which are only half the font size). With the right eye, I could only read the time…
The other day, I printed a self-made eye chart that goes down to 20/2 vision. Obviously, I don’t intend to ever get there (I think not even an eagle could make that. Figures of eagle vision I have heard are in the range of 20/8 to 20/3). It’s just that I decided to put eye charts near several places that I often sit close to and since I don’t have much influence on the distances, I need the smaller Landolt rings to cover the range of possible distances. Looking at the chart as it was lying on the table I realized I could read the 32cm line from what I measured to be 60cm with only little effort. So there’s a good chance I will eventually get to 20/10 vision, which was my initial goal. (Or rather “get back to 20/10”, because I remember this eye test in school when I was 13 and was measured to be “better than 200%”.)
As for the astigmatism, I decided to stop measuring it. Until today, I got consistent axes, but today I got the left at 90 degrees, which is almost perpendicular to my previous measurements. Since I doubt I’m completely stupid, this can only mean that my astigmatism is in fact negligible and since I’m not going to wear cylinder, absolutely no need to quantify it. I’ll go for spherical equivalent only again and save myself the trouble and time to quantify cylinder. (So far, I’ve spent 70% of my time for refractions on getting the cylinder right, readjusting the sphere to the new cylinder, then correcting cylinder again, making sure the axis is correct and so forth).
Main focus now is obviously equalizing my right eye, because even with both eyes open, most of the blur that I perceive comes from the right eye. Diligently patching 10…15 minutes every day. (Fortunately, I never get around to do more, because I surely would if I could.)
When my right is somewhere between -0.50 and -0.25 (and my left hopefully at ±0.00, but I’ll really make this about how the right eye is doing), I’ll make a video for Jake. ?
Lots of love and best wishes also to everyone else!
And that’s a great place to leave things, for today!