Author Topic: Close-work Rehabilitative Lens Power - Advice?  (Read 2579 times)

Offline vraedwulf

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Close-work Rehabilitative Lens Power - Advice?
« on: December 15, 2014, 06:10:37 AM »
My current prescription is as follows:
R: -2.75, -1.75 x 086
L: -4.00

I am interested in using reduced power lenses for close-work (and someday, far-work too), in an attempt to improve my vision with the goal of perhaps one day completely correcting it. Given the astigmatism that I have, what would your advice be regarding the power and cylinder values of rehabilitative lenses to accomplish this goal?

Thanks!

Offline OtisBrown

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Re: Close-work Rehabilitative Lens Power - Advice?
« Reply #1 on: December 15, 2014, 06:49:02 AM »
Hi Vraedwulf,

To calculate a "near vision" power, convert to spherical equivalent.  (Take 1/2 the astig. power and add it.)

R:  -2.75 + (-1) = -3.75 Spherical equivalent, as an example.
L:  -4.00  Spherical.

To calculate a "near" lens, just subtract 2 diopters from both lenses.

For close work this becomes:

R:  -1.75 Diopters
L:  -2.00 Diopters.

When you get these glasses, you can establish your "rough blur" point.  It many be that at 20 inches everything is clear.  In which case, "push away", until you can not make out the letters.  Then "pull in" and find out the "just clear point".

It is possible that point  might be 25 inches.

With a bright light on your reading -- try this:

1) Take your glasses off. 

2) Then try to read at 10 inches.  Print should be clear. 

3)  Then "push away" until you can not read the letters. Then, "pull in" until you can just read the letters.  That point might be about 16 inches.  If it is, you can try to do your reading with no glasses at all.

It is always good to do some experimentation - to find these things out.


My current prescription is as follows:
R: -2.75, -1.75 x 086
L: -4.00

I am interested in using reduced power lenses for close-work (and someday, far-work too), in an attempt to improve my vision with the goal of perhaps one day completely correcting it. Given the astigmatism that I have, what would your advice be regarding the power and cylinder values of rehabilitative lenses to accomplish this goal?

Thanks!
« Last Edit: December 15, 2014, 09:32:16 AM by OtisBrown »

Offline vraedwulf

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Re: Close-work Rehabilitative Lens Power - Advice?
« Reply #2 on: December 15, 2014, 12:24:36 PM »
What a clear and prompt response! Thanks!

My Husband's prescription is:
R: -0.75, -0.25 x 159
L: -0.50, -0.50 x 173

(His eyes are so much better than mine, it makes me jealous!)

Am I correct in assuming that, if he'd like to improve his eyesight, he should actually use plus-lenses for close-work? Perhaps something like: R: +1.00, L: +1.25?

Offline Myoctim

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Re: Close-work Rehabilitative Lens Power - Advice?
« Reply #3 on: December 15, 2014, 04:43:08 PM »
My current prescription is as follows:
R: -2.75, -1.75 x 086
L: -4.00

I am interested in using reduced power lenses for close-work (and someday, far-work too), in an attempt to improve my vision with the goal of perhaps one day completely correcting it. Given the astigmatism that I have, what would your advice be regarding the power and cylinder values of rehabilitative lenses to accomplish this goal?

Thanks!

Hi vraedwulf,

a spherical equivalent (SE) prescription of -3.75D (as recommended by Otis)  at far would be equal to reading at 1/3.75D = 0.2666m -> 27cm / 10.6in without any glasses.
By comparing that image respectively the remaining blur to the image of your nonastigmatic eye at 1/4D = 25cm / 9.8in you easily should get an idea if the SE could work for you (before ordering that lens).

While at low astigmatism like your husband's 0.25D to 0.5D a cylinder is unnecessary unfortunately the situation changes if there is more than 1D of astigmatism. Atleast that's my personal experience at 1.25D of astigmatism :-(

Offline vraedwulf

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Re: Close-work Rehabilitative Lens Power - Advice?
« Reply #4 on: December 16, 2014, 07:04:57 AM »
So let me see if I've got this straight: If my unaided right eye sees as well at 10.6 inches, as my unaided left eye sees at 9.8 inches, then the lens power Otis recommended should work. But if my vision in my right eye is still blurry or distorted under that test, then I’ll need astigmatism correction in my close-work glasses. Is that correct?

If so, then I just took a look and I think I actually pass that test...

Thanks!

Offline OtisBrown

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Re: Close-work Rehabilitative Lens Power - Advice?
« Reply #5 on: December 17, 2014, 06:17:08 PM »
Subject: The issues and difficulties of "just prevention".

Remarks by Dr. Prentice - and I totally agree with him.

http://myopiafree.i-see.org/prent.txt

Do I think you husband is interested in wearing a plus (for near) for six months?  Monitoring his Snellen?  Getting to naked-eye 20/20, by personal confirmation.  If it were me, I would do it, but then I never know about anyone.

Dr. Prentice defines the problem.  Most of us have no interest in the challenge of doing it, or do not want to be bothered by this issue.

The ODs prescribed for the STRONGEST minus possible.  Your husband has a very mild minus lens.  If he checked his own Snellen, he might have 20/30 vision, or better, - which would pass the DMV test.

But, what Prentice said is true, for almost all of us.  Wearing a plus 2.5 for near, and understanding WHY it is necessary, is simply beyond the interest and motivation of most people.

I only define recovery, in terms of Dr. Prentice's statement.

What a clear and prompt response! Thanks!

My Husband's prescription is:
R: -0.75, -0.25 x 159
L: -0.50, -0.50 x 173

(His eyes are so much better than mine, it makes me jealous!)

Am I correct in assuming that, if he'd like to improve his eyesight, he should actually use plus-lenses for close-work? Perhaps something like: R: +1.00, L: +1.25?
« Last Edit: December 17, 2014, 06:27:18 PM by OtisBrown »

Offline Myoctim

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Re: Close-work Rehabilitative Lens Power - Advice?
« Reply #6 on: December 18, 2014, 06:47:40 AM »
So let me see if I've got this straight: If my unaided right eye sees as well at 10.6 inches, as my unaided left eye sees at 9.8 inches, then the lens power Otis recommended should work. But if my vision in my right eye is still blurry or distorted under that test, then I’ll need astigmatism correction in my close-work glasses. Is that correct?

If so, then I just took a look and I think I actually pass that test...

Thanks!

Yes, that's correct.
Otherwise keep a part of the cylinder (same axis) and replace the rest by the SE

So I'm curious if you feel the SE being "bearable" for you.

IMHO each astigmatism seems to be more or less different.
Maybe it's because beside the astigmatism there also are other optical aberrations like coma etc. which influence the resulting blur.