Author Topic: How to start correcting astigmatism?  (Read 12847 times)

Offline Myoctim

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Re: How to start correcting astigmatism?
« Reply #15 on: March 11, 2014, 05:31:41 AM »


My second set of test glasses from Zenni arrived.

I tried CapitalPrince's suggestion but I'm not quite ready for this much reduction yet
R. -0.5D -1.25Dx105
L.  0    -2.00Dx 80
I have lots of blur with a blurry at 20/50 at best combined and roughly 20/60 in each eye alone (blurrier on the right), but these are lenses to work toward being able to use.


Hi Don,

it is said a blur of 1 D astigmatism equals a 0.5D spherical blur.
My personal experience is using a 0.75D astigmatic undercorrection works well.

So for reading you could use
R + 1 D       -1.75D cyl
L + 1.75 D  -3.75D cyl

for distant vision
R -0.5D   -1.75D cyl
L +0.25  -3.25D cyl


Quote from: Don67
One possibility is that I might try the spherical right lens at -2.25 with the L: 0   -2.00Dx 80 to see how that works

unfortunately that would result in overcorrection.
Also, as I posted, it could stimulate your emmetropic meridian to get more myopic. I personally wouldn't risk it.

Offline Don67

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Re: How to start correcting astigmatism?
« Reply #16 on: March 11, 2014, 05:55:53 AM »
Thanks much, Myoctim. 

Just to be sure I understand the logic, you are suggesting going with lower negative/plus spherical correction but with still relatively strong cylinder.  Is that right?  Seems like that should help challenge the myopia while being reasonable/gradual in pushing against the astigmatism. 

Also, did you mean to suggest -3.25D on the cyl for both the reading and distance rather than -3.75D on the reading?  I want to be a bit more cautious on what I order in this range since Zenni charges an extra $9 per pair of glasses with more than -3.0D cyl and they are also recommending a higher lens quality for this prescription which could bring the cost up quite a bit for an experimental pair or two.

Does it seem the reading lenses you suggest would be more helpful in working on hormetic correction than just trying to read at say 17-20 inches without corrective lenses?  I think I understand your logic and it seems worth a try.

As I continue to experiment with this, it seems like my astigmatism and presbyopia are pretty big challenges affecting my ability to go directly after the myopia.
« Last Edit: March 11, 2014, 09:35:30 AM by Don67 »

Offline CapitalPrince

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Re: How to start correcting astigmatism?
« Reply #17 on: March 11, 2014, 09:51:43 AM »
hey Don,

Do you see alot of double vision or wavy things with that amount of astigmatism?
I have about -0.75D astigmatism and its somewhat noticeable.

you are going to have different opinions here, but i think you should just wear a spherical (either low minus or plus) for near and a undercorrection cylinder for distance.

 you definitely do NOT want to use any minus cylinder for near.

Offline Don67

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Re: How to start correcting astigmatism?
« Reply #18 on: March 11, 2014, 10:01:15 AM »
Thanks, CapitalPrince.

Double vision is a better descriptor than wavy I suppose.  The edges of everything tend to appear fuzzy.

FWIW, I've also noticed that if I limit my vision to a narrow vertical slot (e.g. hold my hand over my eye so that I am looking between two fingers), then my left eye vision is about 20/30 on my Snellen (and a blurrier 20/50 for the right eye).

Offline Myoctim

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Re: How to start correcting astigmatism?
« Reply #19 on: March 11, 2014, 02:58:28 PM »
Just to be sure I understand the logic, you are suggesting going with lower negative/plus spherical correction but with still relatively strong cylinder.  Is that right?  Seems like that should help challenge the myopia while being reasonable/gradual in pushing against the astigmatism. 

Also, did you mean to suggest -3.25D on the cyl for both the reading and distance rather than -3.75D on the reading?  I want to be a bit more cautious on what I order in this range since Zenni charges an extra $9 per pair of glasses with more than -3.0D cyl and they are also recommending a higher lens quality for this prescription which could bring the cost up quite a bit for an experimental pair or two.

Hi Don,

sorry, for my typo, of course I meant -3.25D cyl. for both (an undercorrection of 0.75 D) . The less expensive -3.0 D cyl. should also work.

Maybe the "blur factor" by 0.5D sph blur + 1/2 * 0.75D cyl. blur = 0.875 D is too much for a comfortable distant vision (exept for TV).
I guess

-0.75D -1.75D cyl
 0.0D  -3.25 D cyl (or less expensive -3.0D)
 
would give you a more comfortable vision.

Quote from: Don67
Does it seem the reading lenses you suggest would be more helpful in working on hormetic correction than just trying to read at say 17-20 inches without corrective lenses?  I think I understand your logic and it seems worth a try.

also looks like I got you wrong by thinking you want to use that -2.25D and the 0D -2D cyl together at your left eye which would result in overcorrection.

So you can use that R -2.25D SE for distant vision, but I think using a cyl. correction (like -0.75D -1.75D cyl) would give you a more pleasant vision and you are avoiding the risk of equalizing your meridians for the prize of getting more sherical myopia.
IMHO particulary reading at 17 inches could change your nearly emmetropic L -0.25D sph value.

Offline Don67

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Re: How to start correcting astigmatism?
« Reply #20 on: March 11, 2014, 03:45:00 PM »
Thanks, Myoctim.

My 17 inch comment refers to roughly the distance I can stand from my computer monitor which is where I spend most of my day and still see without glasses but with a blur.  So, I was just trying to clarify how best to work on the myopia -- a) simply reading without glasses on and trying to get my eyes to correct the blur, b)/c) using a lower powered minus lens with or without astigmatic correction, or d) I suppose trying to go to a small Diopter plus lens with astigmatic undercorrection.


Offline Don67

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Re: How to start correcting astigmatism?
« Reply #21 on: May 19, 2014, 05:05:20 AM »
It's been a couple of months and so I thought I'd post an update.

Using my Snellen this morning, I can see a clear 20/20 with:
R: -0.75 x -1.75 x 105
L:   0.00 x -3.00 x 80

I've been using a pair of near vision lenses for reading at the blur with:
R: +0.75 x -1.75 x 105
L: +1.50 x -3.00 x 80

My presbyopia seems a bit better although that's hard to measure.

Since I'm feeling my sight is now pretty solid in the current lenses, I guess it's time to try to push things a little more.
I'm considering reducing the sphere and cyl by 0.25 in both lenses for the distance glasses to see how that goes (and correspondingly increasing the near lenses' sphere and cyl. by 0.25).  Does that seem sensible?

Also, anyone have experience of just using a set of bifocals for this ongoing work rather than two separate pairs of glasses?

Offline OtisBrown

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Re: How to start correcting astigmatism?
« Reply #22 on: May 19, 2014, 10:49:21 AM »
Hi Don67,

I know I have my "biased" opinion - but here is what I would attempt to do.

Don> I've been using a pair of near vision lenses for reading at the blur with:
R: +0.75 x -1.75 x 105
L: +1.50 x -3.00 x 80

I know you want to be comfortable - but with that prescription, (spherical equivalent) I would attempt to READ with no lens on.

That is a tough choice for you.  But even Dr. Alex stated that to "reduce" astigmatism (for near) it would be wise to avoid wearing glasses.

The Sph. Equi is L:  +1.5 - (3/2) or 0.0 diopters, for reading at 20 inches.

The other Sph. Equi. is R:  0.75 - (1.75/2) or approximatly 0.75 - 1, or -1/4 diopters.

Most "near" or "add" prescriptions do not "correct" for astigmatism.  But that is just my biased opinion.



Offline Don67

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Re: How to start correcting astigmatism?
« Reply #23 on: May 20, 2014, 05:32:22 AM »
Thanks, TomLu and Otis.  I appreciate the replies and guidance.  I'll attempt to continue the improvements I've had so far.  Dealing with my astigmatism and presbyopia certainly add to my challenge but make it worthwhile to keep trying.

Offline OtisBrown

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Re: How to start correcting astigmatism?
« Reply #24 on: May 22, 2014, 04:51:05 PM »
Hi Don,

Here are a professional's remarks about astigmatism.  I personally use a "spherical" lens to check for any astigmatism I might have.

Here is a video on this important subject:

https://www.youtube.com/watch?v=kKY-Z8gYSAY

For distant objects, >20 feet, I would wear the astigmatic lens.

But "near vision" very seldom requires extreme sharpness.  For near,  I would try to read with no glasses, and only use a lens for distant objects.  This is just how *I* would do it.



Thanks, TomLu and Otis.  I appreciate the replies and guidance.  I'll attempt to continue the improvements I've had so far.  Dealing with my astigmatism and presbyopia certainly add to my challenge but make it worthwhile to keep trying.

Offline Don67

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Re: How to start correcting astigmatism?
« Reply #25 on: May 23, 2014, 02:54:10 AM »
Thanks, Otis.  The man on the video does a nice job explaining this.

Does any have a source for inexpensive test lenses and a lens holder?

Offline OtisBrown

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Re: How to start correcting astigmatism?
« Reply #26 on: May 23, 2014, 03:32:29 AM »
Hi Don,

It is indeed an "extra step" to obtain  your own test lenses - at low cost.  I have seen endless over-prescriptions, that I strongly object to.  This is the reason I obtain my own "minus lenses", have my own Snellen, and do all my own checking.  I go to an OD or MD, but everything they want to PRESCRIBE a lens that I do not need nor want.  There is no point in arguing about this issue. 

This only good source of some test lenses, is Zennioptical.  They cost about $4 per lens.  I will post a video on how to order them in due course.  For me, this is full empowerment.  I do not disparage an OD or MD, but he does not have "time" for me protecting *my* distant vision by my own efforts.  This is part of what Dr. Bates suggested - to avoid wearing of a lens - if you pass the required lines on your own Snellen.

https://www.youtube.com/watch?v=5YTF2D3I4Ao

This is the only source of low-cost lenses to do the type of self-checking that i could find.  What Dr. Alex has discovered, is that "reducing" nearsightedness, also seems to "reduce" astigmatism - and I believe him.  But that also means "reducing" the amount of time you read with an astigmatic lens.  This is indeed an "extra step".  The complete video is here.

http://www.zennioptical.com/howto



Thanks, Otis.  The man on the video does a nice job explaining this.

Does any have a source for inexpensive test lenses and a lens holder?
« Last Edit: May 23, 2014, 03:40:19 AM by OtisBrown »

Offline Don67

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Re: How to start correcting astigmatism?
« Reply #27 on: May 23, 2014, 04:30:15 AM »
Thanks, Otis. 

However, since I'll still need astigmatic correction for distance viewing for quite awhile, I would imagine I need something a little more complicated to check what cyl. I currently need. Is that correct?

Offline Myoctim

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Re: How to start correcting astigmatism?
« Reply #28 on: May 27, 2014, 02:23:11 PM »
However, since I'll still need astigmatic correction for distance viewing for quite awhile, I would imagine I need something a little more complicated to check what cyl. I currently need. Is that correct?

Hi Don,

that's also my idea.
There once was a recommodation for a affordable chinese trial lens set on the Frauenfeld site. 

Because I don't need all that high values from the set I think about only buying the trial frame and some +/- 0.25D and 0.5D spare lenses in sph. and a -0.25 and a -0.5 cyl. lens for checking for any improvement and a possible change in axis.




Offline Myoctim

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Re: How to start correcting astigmatism?
« Reply #29 on: May 28, 2014, 08:41:24 PM »
Hi Myoctim and Don,

Don can avoid "astigmatic" lens for near, but he likes astigmatic for far.  Here is one source of a trial lens kit.

http://www.optometrial.com/trial-lens-sets/232-lens-sets/trial-lens-set-232pc-lens-shiny-plastic-rim-1

The "astigmatic" requires that you rotate a -1 diopter (astigmaic) lens through 180 degrees, and find "sharpest" vision.  But that does require a "trial frame", and the lenses.  I still maintain this is the only way to get your own "best measurement".

I wish some "group" would sell a "reduced" trial frame with spherical and astigmatic lenses, so we could test ourselves.  It would be very instructive and "liberating".  For now, I just use a few lenses from Zennioptical.  If more people would ask - a "market" could develop for some of us.

Hi Otis,

THX for the link.

So how to check for an astigmatism improvement?
-Rotating a + 0.25 cyl. lens in front of my current prescription and looking if it get's clearer?
-Otherwise I would need a bunch of -1.25D cyl, -1.0D cyl., -0.75D cyl. and -0.5D cyl. lenses.

Ordering only a $ 1.5 trial frame

http://www.optometrial.com/trial-lens-sets/trial-frames

and some replacement lenses

http://www.optometrial.com/trial-lens-sets/trial-lens-replace

shouldn't be so expensive.


BTW, it's not a matter of liking the astigmatism correction but simply of needing it. Particulary when driving at a rainy night it's much safer!
For getting an impression what I mean maybe you should simulate a >1D of astigmatism by aligning a +1D cyl. lens with the axis of your existing low astigmatism in a way they add.

I guess without the depth of field by a small pupil you wouldn't be pleased about that acuity!