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Asking for less than perfect IOL in Cataract Surgery
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Andrew Chew
medicine forum beginner


Joined: 24 Mar 2005
Posts: 49

PostPosted: Thu Mar 24, 2005 8:13 pm    Post subject: Re: Dominant eye alternation Reply with quote

"Dr Judy" <mpace99nospam@rogers.com> wrote in message
news:N8KdnYOtMb-fk5jfRVn-gw@rogers.com...
Quote:
"Andrew Chew" <andrew@nospam.alumni.nus.edu.sg> wrote in message
news:1107598404.444.0@spandrell.news.uk.clara.net...

I suffer from mild myopia, average -2.5 D. I enquired with my optician on
what prescription to use for a pair of reading glasses, so that I don't
have to accommodate and she suggested +1.5 to the existing prescription.
I wonder if this is suitable for use with computers since it's
recommended to sit as far back from the monitor as possible.

It depends upon your age and the distance viewed. If you do not want to
accommodate at all (why is this your goal?), then you need a +2.00 or
+2.50 add for the usual near viewing distance of 16 to 18 inches, +1.50
ad for a computer at 20 to 22 inches and +1.00 add for a computer at 24 to
30 inches.

I'm hoping my myopia will improve if I accommodate less. Will see how it
goes...
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Philip D Izaac
medicine forum addict


Joined: 08 May 2005
Posts: 78

PostPosted: Thu Mar 24, 2005 8:13 pm    Post subject: Re: Dominant eye alternation Reply with quote

Hey Andrew, Its great to see someone from Singapore on this newsgroup.

With a +1.50 Add you will not need to accomodate when looking at an object
at 66.66 cm. You will however have to accomodate when looking closer.

Roland J. Izaac
Optometrist
Singapore

"Andrew Chew" <andrew@nospam.alumni.nus.edu.sg> wrote in message
news:1107598404.444.0@spandrell.news.uk.clara.net...
Quote:

"Dr Judy" <mpace99nospam@rogers.com> wrote in message
news:q6adnYHv5JTPmJ3fRVn-uQ@rogers.com...
kemccx@gmail.com> wrote in message
news:1107277327.452378.281120@f14g2000cwb.googlegroups.com...
when one eye is set for distance and one for near - what is the
prescription of the near contact lens? is it relative to the distance
eye?

No, determined relative to the distance prescription for the near eye.
The near lens power is determined by how much "add" the patient needs to
read, then that add is added to the distance power needed in that eye.
Eg: distance Rx is -3.00, add is +1.00, near lens is then -2.00.

The add used is determined by the fitter using trial contact lenses.
Selection depends upon the patient's bifocal add, what type of near work
is done and how much distance blur the patient can tolerate.

Dr judy



I suffer from mild myopia, average -2.5 D. I enquired with my optician on
what prescription to use for a pair of reading glasses, so that I don't
have
to accommodate and she suggested +1.5 to the existing prescription. I
wonder
if this is suitable for use with computers since it's recommended to sit
as
far back from the monitor as possible.

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Andrew Chew
medicine forum beginner


Joined: 24 Mar 2005
Posts: 49

PostPosted: Thu Mar 24, 2005 8:13 pm    Post subject: Re: Dominant eye alternation Reply with quote

"Philip D Izaac" <pdizaac@singnet.com.sg> wrote in message
news:cu43su$4d9$1@reader01.singnet.com.sg...
Quote:
Hey Andrew, Its great to see someone from Singapore on this newsgroup.

With a +1.50 Add you will not need to accomodate when looking at an object
at 66.66 cm. You will however have to accomodate when looking closer.

66.66 cm seems pretty decent. The Singapore Health Promotion Board
recommends at least 50 cm from the monitor and 30 cm for regular reading
materials.
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Philip D Izaac
medicine forum addict


Joined: 08 May 2005
Posts: 78

PostPosted: Thu Mar 24, 2005 8:13 pm    Post subject: Re: Dominant eye alternation Reply with quote

"Andrew Chew" <andrew@nospam.alumni.nus.edu.sg> wrote in message
news:1107667666.71226.0@demeter.uk.clara.net...
Quote:

"Philip D Izaac" <pdizaac@singnet.com.sg> wrote in message
news:cu43su$4d9$1@reader01.singnet.com.sg...
Hey Andrew, Its great to see someone from Singapore on this newsgroup.

With a +1.50 Add you will not need to accomodate when looking at an
object
at 66.66 cm. You will however have to accomodate when looking closer.

66.66 cm seems pretty decent. The Singapore Health Promotion Board
recommends at least 50 cm from the monitor and 30 cm for regular reading
materials.


For a young kid with short arms, maybe; I would keep reading materials at

least 40 cm. away
At this distance (with your 1.50 add) you would still need to accomodate by
1.00D

Have you read the COMET study?

Roland J. Izaac
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Andrew Chew
medicine forum beginner


Joined: 24 Mar 2005
Posts: 49

PostPosted: Thu Mar 24, 2005 8:13 pm    Post subject: Re: Dominant eye alternation Reply with quote

"Philip D Izaac" <pdizaac@singnet.com.sg> wrote in message
news:cu4iq0$4q2$1@reader01.singnet.com.sg...

Quote:
For a young kid with short arms, maybe; I would keep reading materials at
least 40 cm. away
At this distance (with your 1.50 add) you would still need to accomodate
by
1.00D

Have you read the COMET study?

http://www.nei.nih.gov/neitrials/static/study9.asp
Yes, they seem to have concluded plus lenses only help in the first year on
wearing them, then the eye adapts or something.

I also read that chicks which were made to wear plus lenses became
hyperopic and those wearing minus lenses became myopic. See
http://vision.berkeley.edu/wildsoet/myopiaPrimer.html under "Animal models
for myopia & emmetropization". So it's actually possible to induce myopia &
hyperopia just by wearing wrong prescriptions?
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Dr Judy
medicine forum Guru


Joined: 07 May 2005
Posts: 304

PostPosted: Thu Mar 24, 2005 8:13 pm    Post subject: Re: Dominant eye alternation Reply with quote

"Andrew Chew" <andrew@nospam.alumni.nus.edu.sg> wrote in message
news:1107632746.19768.0@echo.uk.clara.net...
Quote:

"Dr Judy" <mpace99nospam@rogers.com> wrote in message
news:N8KdnYOtMb-fk5jfRVn-gw@rogers.com...
"Andrew Chew" <andrew@nospam.alumni.nus.edu.sg> wrote in message
news:1107598404.444.0@spandrell.news.uk.clara.net...

I suffer from mild myopia, average -2.5 D. I enquired with my optician
on what prescription to use for a pair of reading glasses, so that I
don't have to accommodate and she suggested +1.5 to the existing
prescription. I wonder if this is suitable for use with computers since
it's recommended to sit as far back from the monitor as possible.

It depends upon your age and the distance viewed. If you do not want to
accommodate at all (why is this your goal?), then you need a +2.00 or
+2.50 add for the usual near viewing distance of 16 to 18 inches, +1.50
ad for a computer at 20 to 22 inches and +1.00 add for a computer at 24
to 30 inches.

I'm hoping my myopia will improve if I accommodate less. Will see how it
goes...

There is no evidence that reducing accommodation will reverse myopia. There
is some evidence that near work is a factor in the development of myopia in
the first place, however, it is not clear that accommodation is the reason
for the near work factor. Family history of myopia explains about 85% of
myopia.

If you think you have pseudo myopia, ask your eye doctor next time you are
in for an exam to do a cycloplegic refraction. The difference, if any,
between your non cycloplegic and your cycloplegic refraction is the maximum
amount of myopia you can expect to reduce by not accommodating.

Dr Judy
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Dr Judy
medicine forum Guru


Joined: 07 May 2005
Posts: 304

PostPosted: Thu Mar 24, 2005 8:13 pm    Post subject: Re: Dominant eye alternation Reply with quote

"Andrew Chew" <andrew@nospam.alumni.nus.edu.sg> wrote in message
news:1107684748.76546.0@demeter.uk.clara.net...
Quote:

http://www.nei.nih.gov/neitrials/static/study9.asp
Yes, they seem to have concluded plus lenses only help in the first year
on wearing them, then the eye adapts or something.

I also read that chicks which were made to wear plus lenses became
hyperopic and those wearing minus lenses became myopic. See
http://vision.berkeley.edu/wildsoet/myopiaPrimer.html under "Animal models
for myopia & emmetropization". So it's actually possible to induce myopia
& hyperopia just by wearing wrong prescriptions?

Only in neonates (newborns). Those experiments were done with newly
hatched chicks who were forced to wear high (10D) power lenses to simulate
being born with high refractive error. Both The simulated myopes (wearing
+10) and the simulated hyperopes (-10) altered eye growth so that the
eye/lens system had a net refractive error approaching zero. This process is
called emmetropization and no relevance to the development and/or correction
of refractive error in non neonates.

In humans, babies born with large refractive do the same thing so that by
age 2 or 3, most children do not have significant refractive error.
Emmetropization does not occur after age 3 to 4, which is why refractive
error that develops after that age is not self correcting and people need
glasses.

Those who advocate using plus lenses to reverse myopia in adults ignore the
fact that it would only be effective in babies and toddlers.

Dr Judy
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Andrew Chew
medicine forum beginner


Joined: 24 Mar 2005
Posts: 49

PostPosted: Thu Mar 24, 2005 8:13 pm    Post subject: Re: Dominant eye alternation Reply with quote

"Dr Judy" <mpace99nospam@rogers.com> wrote in message
news:Rt2dnaWiwI6t8ZvfRVn-3A@rogers.com...

Quote:
If you think you have pseudo myopia, ask your eye doctor next time you are
in for an exam to do a cycloplegic refraction. The difference, if any,
between your non cycloplegic and your cycloplegic refraction is the
maximum amount of myopia you can expect to reduce by not accommodating.

Good idea. I'll be doing that soon.
Back to top
Rishi Giovanni Gatti
medicine forum beginner


Joined: 06 Feb 2005
Posts: 21

PostPosted: Thu Mar 24, 2005 8:13 pm    Post subject: Re: Dominant eye alternation Reply with quote

"Andrew Chew" <andrew@nospam.alumni.nus.edu.sg> wrote in message news:<1107791019.38662.0@demeter.uk.clara.net>...
Quote:
"Dr Judy" <mpace99nospam@rogers.com> wrote in message
news:Rt2dnaWiwI6t8ZvfRVn-3A@rogers.com...

If you think you have pseudo myopia, ask your eye doctor next time you are
in for an exam to do a cycloplegic refraction. The difference, if any,
between your non cycloplegic and your cycloplegic refraction is the
maximum amount of myopia you can expect to reduce by not accommodating.

Good idea. I'll be doing that soon.

Don't be idiotic.

Let them remain in their harmful ignorance.

You remain pure, don't let them ruin your eyes with chemicals.

It's very easy to learn how to see again, just study the books and
start the practice of the rest methods.
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Rishi Giovanni Gatti
medicine forum beginner


Joined: 06 Feb 2005
Posts: 21

PostPosted: Thu Mar 24, 2005 8:13 pm    Post subject: Re: Dominant eye alternation Reply with quote

Quote:
In humans, babies born with large refractive do the same thing so that by
age 2 or 3, most children do not have significant refractive error.
Emmetropization does not occur after age 3 to 4, which is why refractive
error that develops after that age is not self correcting and people need
glasses.

Those who advocate using plus lenses to reverse myopia in adults ignore the
fact that it would only be effective in babies and toddlers.

Dr Judy

Although you have never witnessed it, there are thousands of people
who are recovering from refractive errors just by rest methods.

It is very easy to do it temporarily, more difficult to do it
permanently.

Continued treatment brings about a complete cure if the patient
continues.
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John Hasenkam
medicine forum beginner


Joined: 24 Mar 2005
Posts: 1

PostPosted: Thu Mar 24, 2005 8:13 pm    Post subject: Re: Dominant eye alternation(laugh away dominance) Reply with quote

Laughter plays tricks with your eyes
http://abc.net.au/science/news/stories/s1294404.htm

....
"Normally people just don't see both [versions] at the same time," he says.

But when you laugh the images blend together and the illusion is lost
leaving only a flat 2D drawing.
....

"Dr Judy" <mpace99nospam@rogers.com> wrote in message
news:Rt2dnaWiwI6t8ZvfRVn-3A@rogers.com...
Quote:
"Andrew Chew" <andrew@nospam.alumni.nus.edu.sg> wrote in message
news:1107632746.19768.0@echo.uk.clara.net...

"Dr Judy" <mpace99nospam@rogers.com> wrote in message
news:N8KdnYOtMb-fk5jfRVn-gw@rogers.com...
"Andrew Chew" <andrew@nospam.alumni.nus.edu.sg> wrote in message
news:1107598404.444.0@spandrell.news.uk.clara.net...

I suffer from mild myopia, average -2.5 D. I enquired with my optician
on what prescription to use for a pair of reading glasses, so that I
don't have to accommodate and she suggested +1.5 to the existing
prescription. I wonder if this is suitable for use with computers
since
it's recommended to sit as far back from the monitor as possible.

It depends upon your age and the distance viewed. If you do not want
to
accommodate at all (why is this your goal?), then you need a +2.00 or
+2.50 add for the usual near viewing distance of 16 to 18 inches,
+1.50
ad for a computer at 20 to 22 inches and +1.00 add for a computer at 24
to 30 inches.

I'm hoping my myopia will improve if I accommodate less. Will see how it
goes...

There is no evidence that reducing accommodation will reverse myopia.
There
is some evidence that near work is a factor in the development of myopia
in
the first place, however, it is not clear that accommodation is the
reason
for the near work factor. Family history of myopia explains about 85% of
myopia.

If you think you have pseudo myopia, ask your eye doctor next time you are
in for an exam to do a cycloplegic refraction. The difference, if any,
between your non cycloplegic and your cycloplegic refraction is the
maximum
amount of myopia you can expect to reduce by not accommodating.

Dr Judy

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Dr Judy
medicine forum Guru


Joined: 07 May 2005
Posts: 304

PostPosted: Thu Mar 24, 2005 8:13 pm    Post subject: Re: Dominant eye alternation Reply with quote

"Andrew Chew" <andrew@nospam.alumni.nus.edu.sg> wrote in message
news:1107598404.444.0@spandrell.news.uk.clara.net...
Quote:

"Dr Judy" <mpace99nospam@rogers.com> wrote in message
news:q6adnYHv5JTPmJ3fRVn-uQ@rogers.com...
kemccx@gmail.com> wrote in message
news:1107277327.452378.281120@f14g2000cwb.googlegroups.com...
when one eye is set for distance and one for near - what is the
prescription of the near contact lens? is it relative to the distance
eye?

No, determined relative to the distance prescription for the near eye.
The near lens power is determined by how much "add" the patient needs to
read, then that add is added to the distance power needed in that eye.
Eg: distance Rx is -3.00, add is +1.00, near lens is then -2.00.

The add used is determined by the fitter using trial contact lenses.
Selection depends upon the patient's bifocal add, what type of near work
is done and how much distance blur the patient can tolerate.

Dr judy



I suffer from mild myopia, average -2.5 D. I enquired with my optician on
what prescription to use for a pair of reading glasses, so that I don't
have to accommodate and she suggested +1.5 to the existing prescription. I
wonder if this is suitable for use with computers since it's recommended
to sit as far back from the monitor as possible.

It depends upon your age and the distance viewed. If you do not want to
accommodate at all (why is this your goal?), then you need a +2.00 or +2.50
add for the usual near viewing distance of 16 to 18 inches, +1.50 ad for a
computer at 20 to 22 inches and +1.00 add for a computer at 24 to 30 inches.

It doesn't matter what your distance Rx is, these are all specified as adds.
For example, if you are a 2.50 myope, reading at 16 inches the add is +2.50
and the resultant (-2.50 +2.50) is zero, ie take your glasses off. For the
computer at 28 inches the resultant (-2.50 +1.00) is -1.50 readers.

Be sure to have your eye examiner demonstrate the resultant single vision
reading glasses in a trial frame and check the actual range of clear vision
to make sure it suits you.

Dr Judy

Quote:

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Dr. Leukoma
medicine forum Guru


Joined: 30 Apr 2005
Posts: 1283

PostPosted: Thu Mar 24, 2005 8:13 pm    Post subject: Re: Very Odd Vision Disturbance Reply with quote

This reminded me of one of those factoids I learned in Binocular Vision
101 that I haven't ever needed in clinical practice more than 20 years
later. But, here is my theory for what it is worth.

It would seem to me that you could be suffering from intermittent
esophoria, i.e. the eyes turning in. This may also be accompanied by
farsightedness. The visual system uses a number of cues to perceive
depth. One set of cues is termed "oculomotor cues." In other words,
we normally converge our eyes and accommodate when seeing things
closeup. If the image of the object of regard falls on the retina
nasally to the fovea, as would happen when the eyes over-converge, then
the object will appear to be further away. The opposite case, i.e. the
image falling temporally to the fovea when the eyes are underconverged,
would cause the opposite effect. Of course, the opposite situation can
also exist, i.e. the eyes underconverge, then all of the sudden snap
into the proper vergence, causing the object to change from appearing
closer than normal to further away.

So, in summary, it sounds to me like there is some undiagnosed,
intermittent vergence disorder, or heterophoria, causing this
phenomenon. Of course, the question of why this does not occur at very
close range such as reading distance can be explained by the fact that
your eyes may be going from binocular mode to monocular mode. High
heterophorias, especially convergence insufficiency, often decompensate
as we get older, or under conditions of extreme fatigue. If the
heterophoria decompensates into a frank strabismus, i.e. eyes crossing,
then this might conceivably trigger a cat scan or MRI to rule out some
type of lesion.

DrG



Jim M wrote:
Quote:
Hi

I'm having a problem with, I think, my vision and I was hoping
someone
could help. It's difficult to explain, but here's what the issue is:

Sometimes when I'm looking at something within a certain distance (I
would guess about 5 feet away at a minimum and a maximum of about
10-15
feet), I see things oddly. It seems like I'm viewing something from
a
farther distance than I actually am. For example, I will be sitting
at
my desk looking at the wall (a couple of feet away). All of a
sudden,
it feels like I'm looking at the wall from a distance of about 10
feet
away. If I blink or look away, it goes away. And this only happens
to
things that are sortof close to me. It won't happen if I'm looking
down the street, or if I'm looking at my hand.

Like I said, this is very odd. I had this when I was a little
kid--it
used to accompany high fevers, but now it's back (after about a 25
year
hiatus). I've been to my regular doctor and I've been to an eye
doctor
to have my eyes examined. I explained the problem to both doctors
and
neither has ever heard of anything like this. When I was younger I
underwent a battery of tests (the only one I can remember is the CAT
scan) and they could find nothing wrong with me. Has anyone ever
heard
of anything like this? I just went to get a CAT scan yesterday and
the
nurse was asking about my symptoms. She suggested a depth perception
problem. Could this be it?

If you would like more information, please let me know. Any help
would
be greatly appreciated.

Thank you.

Jim
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Andrew Chew
medicine forum beginner


Joined: 24 Mar 2005
Posts: 49

PostPosted: Thu Mar 24, 2005 8:13 pm    Post subject: Re: Dominant eye alternation Reply with quote

"Dr Judy" <mpace99nospam@rogers.com> wrote in message
news:q6adnYHv5JTPmJ3fRVn-uQ@rogers.com...
Quote:
kemccx@gmail.com> wrote in message
news:1107277327.452378.281120@f14g2000cwb.googlegroups.com...
when one eye is set for distance and one for near - what is the
prescription of the near contact lens? is it relative to the distance
eye?

No, determined relative to the distance prescription for the near eye.
The near lens power is determined by how much "add" the patient needs to
read, then that add is added to the distance power needed in that eye.
Eg: distance Rx is -3.00, add is +1.00, near lens is then -2.00.

The add used is determined by the fitter using trial contact lenses.
Selection depends upon the patient's bifocal add, what type of near work
is done and how much distance blur the patient can tolerate.

Dr judy



I suffer from mild myopia, average -2.5 D. I enquired with my optician on
what prescription to use for a pair of reading glasses, so that I don't have
to accommodate and she suggested +1.5 to the existing prescription. I wonder
if this is suitable for use with computers since it's recommended to sit as
far back from the monitor as possible.
Back to top
Ian Hodgson Opticians Ltd
medicine forum beginner


Joined: 06 May 2005
Posts: 24

PostPosted: Thu Mar 24, 2005 8:13 pm    Post subject: Re: Colour blindness Reply with quote

<g.gatti@agora.it> wrote in message
news:1107345585.778743.71480@o13g2000cwo.googlegroups.com...
Quote:
All problems of colour perception are due to mental strain.

The above comment is a load of ??*!


Colour vision defects, a term much prefered to colour blindness, are well
understood. In the retina
there are three types of cone receptors which respond respectively to red
light, green light and blue light.
The work identifying the visual pigments was done in the 1930's by Arnold
Soresby ( I think). Colour vision problems
are related to the lack of these pigments.

Colour vision is classified as Protanopia (red), deutranopia (green),
tritanopia (blue); there are two
other classifications tetratanopia ( which has a disputed existance) and
true monochromatism ( no colour perception), the
latter being very rare see the book by Sachs (?) about the Trioband
islanders for a fuller explanation.

The underlying cause for the lack of visual pigment is either genetic (
typically 10% of all males have a color vision defect),
or acquired due to disease or drug toxicity. Examples of the former may be
diabetes and the latter alcohol or quinine.

The problems of colour vision following on from a cataract operation may be
due to the spectral transmission characteristics of the
implant, also as you get older the media of the eye change their spectral
transmission. If one eye has an implant and the other does not
I have had reported to me differences in the colour response between the two
eyes.

As to whether one eye only can be colour deficient it is assumed to be
bilateral in genetic cases, though I would not be surprised that uniocular
may occur as, if I remember correctly Dalton who first described protanopia
only had it in one eye. And in acquired cases monocular deficiency
could certainly be present.

The only mental strain will be gatti getting his head around such concepts!

Regards



Ian Hodgson - Isle of Man
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