Re: Asking for less than perfect IOL in Cataract Surgery

quattrocchi wrote:
> When I go in for my cataract pre-surgery sessions in about 6 weeks,
is it really
> _practical_ to have a 20/20 iol put in. I wonder about asking them to
aim for a
> light myopic lens.>

> script with the L cataract which is uncorrectable with glasses:
> R L [cataract eye]
> sp -4.00 -4.50
> cyl -3.00 -3.25
> axis 15 155

So you are just getting the one eye done?

At the moment in your left eye you are -7.75 myopic in one direction
and -4.50 in another direction 90 degrees to that.

Thats a great deal of minus in either direction.

**if** it were possible to accurately fit an IOL to give you no myopia
but leave you with the astigmatism, then you would be astigmatic in one
direction of -1.5D and astigmatic in tother 90 degrees from that at
+1.5.

Because your optical error would then be only 1.5D either side of the
retina that might actually give you vastly superior vision than you
currently have in your very similar right eye uncorrected - especially
in bright conditions. Possibly in bright conditions you could drive
and be able to see 20/40 or better without correction.

Hopefully can get a result that is close to no myopia and then report
back how well you can see with the remaining astigmatism.

Andrew

<(E-Mail Removed)> schreef in bericht
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>> script with the L cataract which is uncorrectable with glasses:
>> R L [cataract eye]
>> sp -4.00 -4.50
>> cyl -3.00 -3.25
>> axis 15 155

> At the moment in your left eye you are -7.75 myopic in one direction
> and -4.50 in another direction 90 degrees to that.

Resulting in a astigmatic amount of 3.25 dpt.

> **if** it were possible to accurately fit an IOL to give you no myopia
> but leave you with the astigmatism, then you would be astigmatic in one
> direction of -1.5D and astigmatic in tother 90 degrees from that at
> +1.5.

Wrong Andrew, the result is a mixed astigmatic myopic/hypermetropic eye.
In one direction 1.50 dpt myopic and in the other direction 1.75
hypermetropic.
The amount of astigmatism still being 3.25 dpt.

--
Jan (normally Dutch spoken)

<Jan> wrote:
> <(E-Mail Removed)> schreef in bericht
> news:(E-Mail Removed) oups.com...
> >> script with the L cataract which is uncorrectable with glasses:
> >> R L [cataract eye]
> >> sp -4.00 -4.50
> >> cyl -3.00 -3.25
> >> axis 15 155
>
> > At the moment in your left eye you are -7.75 myopic in one
direction
> > and -4.50 in another direction 90 degrees to that.
>
> Resulting in a astigmatic amount of 3.25 dpt.
>
> > **if** it were possible to accurately fit an IOL to give you no
myopia
> > but leave you with the astigmatism, then you would be astigmatic in
one
> > direction of -1.5D and astigmatic in tother 90 degrees from that at
> > +1.5.
>
> Wrong Andrew, the result is a mixed astigmatic myopic/hypermetropic
eye.
> In one direction 1.50 dpt myopic and in the other direction 1.75
> hypermetropic.
> The amount of astigmatism still being 3.25 dpt.
>
> --
> Jan (normally Dutch spoken)

Jan

I am not sure how you arrive at your answer or what part of my answer
is incorrect. I clearly indicated a mixed astigmatic eye scenario for
an eye with no myopia.

For a presumed case of regular astigmatism dont we expect to have equal
amounts of astigmatism either side of the retina?

Ie 3.25/2 = +/-1.625D?

Can you explain your answer please?

Thanks

Andrew

<(E-Mail Removed)> schreef in bericht
news:(E-Mail Removed) oups.com...
>> Wrong Andrew, the result is a mixed astigmatic myopic/hypermetropic
> eye.
>> In one direction 1.50 dpt myopic and in the other direction 1.75
>> hypermetropic.
>> The amount of astigmatism still being 3.25 dpt.

> I am not sure how you arrive at your answer or what part of my answer
> is incorrect. I clearly indicated a mixed astigmatic eye scenario for
> an eye with no myopia.
>
> For a presumed case of regular astigmatism dont we expect to have equal
> amounts of astigmatism either side of the retina?
>
> Ie 3.25/2 = +/-1.625D?
>
> Can you explain your answer please?

For me it is astonishing to see Andrew, who says he can determine a
character or behavior by knowing the persons ametropia, having such a lack
in knowledge about ametropia in human eyes.
I already explained your mixed astigmatic eye is in one direction myopic and
not ''non myopic''
If you don not know what you are talking about then please leave.

--
Jan (normally Dutch spoken)

<Jan> wrote:
> <(E-Mail Removed)> schreef in bericht
> news:(E-Mail Removed) oups.com...
> >> Wrong Andrew, the result is a mixed astigmatic
myopic/hypermetropic
> > eye.
> >> In one direction 1.50 dpt myopic and in the other direction 1.75
> >> hypermetropic.
> >> The amount of astigmatism still being 3.25 dpt.
>
> > I am not sure how you arrive at your answer or what part of my
answer
> > is incorrect. I clearly indicated a mixed astigmatic eye scenario
for
> > an eye with no myopia.
> >
> > For a presumed case of regular astigmatism dont we expect to have
equal
> > amounts of astigmatism either side of the retina?
> >
> > Ie 3.25/2 = +/-1.625D?
> >
> > Can you explain your answer please?
>
> For me it is astonishing to see Andrew, who says he can determine a
> character or behavior by knowing the persons ametropia, having such a
lack
> in knowledge about ametropia in human eyes.
> I already explained your mixed astigmatic eye is in one direction
myopic and
> not ''non myopic''
> If you don not know what you are talking about then please leave.
>

Jan

I agree I am not an expert on prescriptions. I just have a rather
simple understanding.

If I am wrong it would be nice to know why that is so.

Here is the original prescription:

R L [cataract eye]
sp -4.00 -4.50
cyl -3.00 -3.25
axis 15 155
add +3.00 +1.25 (progressives)
add +2.50 +0.75 (bifocal)



So we agreed he is has myopia of -4.5 in one direction and -7.75 in
the other

To make this easier for me to understand lets say he had a series of
operations to get the best possible refraction while remaining
astigmatic.

1st operation removes 4.5D of sphere

-4.5 -7.75 (prior to an operation)


0.00 -3.25 (after first operation)


2nd operation removes 1.5D of sphere

+1.5 -1.75

Final operation to produce best possible refraction for mixed
astigmatic eye using a none toric IOL removes one eight of D of sphere.
(0.125D)

+1.6125 -1.6125

So in this scenario the mixed astigmatic eye has equal but opposite
amounts of blurr either side of the retina but at 90 degrees to each
other.

To get +1.75 - 1.5 reguires an **overshoot** of best possible outcome
(for a none toric IOL) by one eighth of a diopter.

If I am wrong where have i made a mistake?

Can somebody help out here please?

Thanks

Andrew

Oops!

I said

>>So in this scenario the mixed astigmatic eye has equal but opposite
amounts of blurr either side of the retina but at 90 degrees to each
other.

The cylinder that creates the astigmatism is in only one plane of
course. So that the maximum hypermetropic blurr of 1.6125 is in the
same line of the maximum minus blurr of -1.6125D with a central point
being the retina.

Correct?

Andrew

<(E-Mail Removed)> schreef in bericht
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> Oops!
>
> I said
>
>>>So in this scenario the mixed astigmatic eye has equal but opposite
> amounts of blurr either side of the retina but at 90 degrees to each
> other.
>
> The cylinder that creates the astigmatism is in only one plane of
> course. So that the maximum hypermetropic blurr of 1.6125 is in the
> same line of the maximum minus blurr of -1.6125D with a central point
> being the retina.
>
> Correct?

No.

First of all the blur is ON the retina, the theoretical sharp focus LINES
(not points) are situated in front and behind the retina and as you said
before at a 90 degree angle to each other (in your example)
The blur on the retina is an out of focus mix of the two different placed
focus lines.

As a said before:
In earlier posting by you, you suggest you can point out different type of
personalities just by knowing (measuring?) the type of ametropia.
If you do not understand right now what myopia, hypermetropia or astigmatism
stands for, how did you before?

My advise Andrew, keep your mouth shut on eye(care) subjects like ametropia
or buy some books on the subject and come back later as soon everything is
clear to you.

--
Jan (normally Dutch spoken)

<Jan> wrote:
> <(E-Mail Removed)> schreef in bericht
> news:(E-Mail Removed) oups.com...
> > Oops!
> >
> > I said
> >
> >>>So in this scenario the mixed astigmatic eye has equal but
opposite
> > amounts of blurr either side of the retina but at 90 degrees to
each
> > other.
> >
> > The cylinder that creates the astigmatism is in only one plane of
> > course. So that the maximum hypermetropic blurr of 1.6125 is in
the
> > same line of the maximum minus blurr of -1.6125D with a central
point
> > being the retina.
> >
> > Correct?
>
> No.
>
> First of all the blur is ON the retina, the theoretical sharp focus
LINES
> (not points) are situated in front and behind the retina and as you
said
> before at a 90 degree angle to each other (in your example)
> The blur on the retina is an out of focus mix of the two different
placed
> focus lines.
>
> As a said before:
> In earlier posting by you, you suggest you can point out different
type of
> personalities just by knowing (measuring?) the type of ametropia.
> If you do not understand right now what myopia, hypermetropia or
astigmatism
> stands for, how did you before?
>
> My advise Andrew, keep your mouth shut on eye(care) subjects like
ametropia
> or buy some books on the subject and come back later as soon
everything is
> clear to you.
>

Jan

We seem to agree that best possible correction for this case results in
mixed astigmatism of +/-1.6125

Andrew

<(E-Mail Removed)> schreef in bericht
news:(E-Mail Removed) oups.com...
> We seem to agree that best possible correction for this case results in
> mixed astigmatism of +/-1.6125
>
> Andrew

We don't

--
Jan (normally Dutch spoken)

"Andrew Judd via MedKB.com" <(E-Mail Removed)> schreef in bericht
news:(E-Mail Removed)...
> Jan, my original comment of +1.5/-1.5 was based on me misreading -3.25
> for -
> 3.00 but i feel your correction to +1.75/-1.5 was based on you being a bit
> hasty in proving me wrong. Subsequently I did not admit my error and
> came
> up with yet another maths error instead of what i still feel would have
> been a reasonable outcome of no spherical error for those wanting
> uncorrected distance vision.

Andrew, I am afraid you never learn.
In your example there is still a spherical error along with an astigmatic
one.

For me it is still astonishing to see Andrew, who says he can determine a
character or behavior by knowing the persons ametropia, having such a lack
in knowledge about just these different kinds of ametropia in human eyes.

>
> From my point of view I have exhausted my interest in this area but have
> learnt some useful stuff.

Lets say, you think you have learned.
Others might have a different view.

--
Jan (normally Dutch spoken)