How to measure near vision?
Posted , 5 users are following.
I'd like to track the loss of uncorrected near vision when I get my artificial lens. I printed a standard Jaeger chart, but J1 is far too easy. I'm thinking a logmar chart that goes well into negative numbers - at least to -0.3 - would be more accurate. Has anyone run across a printable chart like that?
I expect I will misuse any such chart. The standard logmar test for near vision seems to specify 16 inches / 40 cm, but I am more concerned with the smallest type I can read regardless of distance, so I will probably just move the chart as needed to read the smallest letters I can. Any suggestions would be appreciated.
0 likes, 6 replies
RonAKA phil09
Edited
I am not aware of one, but you could compress the PDF version of the Jaeger chart and print it compressed instead of actual size. It may at some point be limited by the resolution of your printer.
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But, I am not sure of the value of it in any case. If you expect to get better than J1 you are probably going to need a more myopic lens than would be practical to use with an IOL and still expect distance vision in the other eye.
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A more realistic test may be to try reading a standard Jaeger chart in dimmer and dimmer light. That is more of a real world limitation of IOL lenses. When the pupil opens up reading vision goes downhill very quickly when you have no accommodation. The practical application of this is in being able to read the menu in a restaurant with dim lighting. That kind of separates the men from the boys at a dinner. The ones with more limited reading ability will be scrambling to find their reading glasses or borrow some from others, or be lighting up the flashlight on their phone. It is a bit of a humorous scene at a table with a bunch of seniors! Or, as in the case of my wife, who has distance vision, and often forgets her reading glasses, I end up reading the menu to her. I have not been stumped yet, but I have come close in very dim restaurants with my -1.60 D mini-monovision.
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Have you checked apps that may be available for your phone? There may be one that works. Have not tried any.
phil09 RonAKA
Edited
Thanks, RonAKA, some good suggestions there.
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"But, I am not sure of the value of it in any case. If you expect to get better than J1 you are probably going to need a more myopic lens than would be practical..."
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No, I would be pleased to get J1 at any distance with my artificial lens. My purpose is just to understand how much near vision acuity I will be losing. If I'm being honest, there probably isn't any value in it, it's just the kind of thing I like to know...
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Lighting is probably harder for me to control and quantify, but I certainly agree restaurants can be tough. The Cheesecake Factory gives me a hard time already - I think their incandescent light bulbs can't be more than 3w. They must have them made special...
RonAKA phil09
Edited
Getting more than J1 in the near eye is easy. You just target more myopia. When I discussed my target of -1.50 D with the surgeon he kind of smiled and said "OK, I have done as much as -3.0 D", indicating that he would do that but he didn't think it was a good idea.
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My thoughts are that the trick with mini-monovision is to get as close to plano as you can in the distance eye, and use as little myopia as you can to get your needed reading vision. If you push the near eye myopia to hard you can end up with a gap in the middle.
phil09 RonAKA
Posted
I agree.
Guest phil09
Edited
i bought an official Jagger chart off Amazon and also used an app on my iPad called Eye Chart Pro. The free version has distance charts and a near chart.
trilemma phil09
Posted
How about putting a bunch of text or random characters into a word processor file. I started each line with a number for font size. I would terminate each run-on line with a new line, and change the font of that.
For random characters I used a program that generates random passwords. Copy, paste. You can use any method you like.
On some word processing programs, 6 font may be the smallest to select from a drop-down list. You may be able to manually enter 4 or 3 or 1 or whatever for smaller text.
I understand that this is not an algorithm, but maybe is enough to get you started thinking about a method.