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Need to know specific name of computerized phoropter
Need to know specific name of computerized phoropter
I just had cataract surgery in my left eye last week, and an
intraocular lens was placed by the ophthalmologist. I'm having the
right eye done in a few days. My vision in my left eye, with the
implanted lens, is excellent. I haven't had it checked yet but I'm
guessing it's 20/15. Prior to the surgery, it was about 20/200.
My question: I believe that the prescription the Doc took for the
intraocular lenses was done, not by a traditional phoropter (that
device with the two hundred lenses where you are asked, "which is
better 1 or 2) but instead was done with a computer controlled device
that you look into and measurements are taken by the computer. I'm
guessing that the measurements involve the curvature of the cornea.
I'm convinced that whatever this device is called, it's accuracy is
far superior to the conventional phoropter because my vision has never
been sharper (and I've worn glasses my whole life).
Does anyone know the name of this device? Thanks for info.
I just had cataract surgery in my left eye last week, and an
intraocular lens was placed by the ophthalmologist. I'm having the
right eye done in a few days. My vision in my left eye, with the
implanted lens, is excellent. I haven't had it checked yet but I'm
guessing it's 20/15. Prior to the surgery, it was about 20/200.
My question: I believe that the prescription the Doc took for the
intraocular lenses was done, not by a traditional phoropter (that
device with the two hundred lenses where you are asked, "which is
better 1 or 2) but instead was done with a computer controlled device
that you look into and measurements are taken by the computer. I'm
guessing that the measurements involve the curvature of the cornea.
I'm convinced that whatever this device is called, it's accuracy is
far superior to the conventional phoropter because my vision has never
been sharper (and I've worn glasses my whole life).
Does anyone know the name of this device? Thanks for info.
Re: Need to know specific name of computerized phoropter
In article
<cb457b83-3034-4b75-a357-4d3d09b92c0e@m1g2000pre.googlegroups,com >,
BobKK47 <bkk@uplink,net > wrote:
I'm not a doctor, but have had cataract surgery in both eyes.
> I just had cataract surgery in my left eye last week, and an
> intraocular lens was placed by the ophthalmologist. I'm having the
> right eye done in a few days. My vision in my left eye, with the
> implanted lens, is excellent. I haven't had it checked yet but I'm
> guessing it's 20/15. Prior to the surgery, it was about 20/200.
It may be too soon to tell, but I hope this isn't bad news. The eye
continues to heal over the first few weeks, and most people experience a
change in vision as the eye changes shape due to healing.
> My question: I believe that the prescription the Doc took for the
> intraocular lenses was done, not by a traditional phoropter (that
> device with the two hundred lenses where you are asked, "which is
> better 1 or 2) but instead was done with a computer controlled device
> that you look into and measurements are taken by the computer. I'm
> guessing that the measurements involve the curvature of the cornea.
Cataract surgery involves eliminating the refraction caused by the lens
inside your eye. There is no way to measure how much this refraction
is, but it is generally so large that ignoring it causes big problems in
vision, thus the IOL. The best that can be done is to measure the
curvature of the cornea and the distance between the cornea and the
retina. Your doctor takes these numbers and plugs them into a formula,
adding a fudge factor based on experience, and any changes due to doctor
decisions or patient requests. This is how the doctor determines the
strength of the IOL to implant. I was lucky, both eyes ended up
perfect. My reading indicates that a reasonable goal is plus or minus
.5D. An optometrist can do much better with a phoropter. However, a
phoropter is useless in determining the strength for the IOL.
> I'm convinced that whatever this device is called, it's accuracy is
> far superior to the conventional phoropter because my vision has never
> been sharper (and I've worn glasses my whole life).
My suspicion is that your vision is so fine, because the cataract was
removed. Based on my experience, this is a major, and welcome,
improvement.
> Does anyone know the name of this device? Thanks for info.
I don't know the name, but it uses sound waves to measure the distance.
I would suggest that at your next appointment, ask the staff to tell you
what your vision is in the left eye. Also, ask the doctor to verify
what I posted, since things change and not every doctor does the surgery
the same.
--
Dan Abel
Petaluma, California USA
dabel@sonic,net
In article
<cb457b83-3034-4b75-a357-4d3d09b92c0e@m1g2000pre.googlegroups,com >,
BobKK47 <bkk@uplink,net > wrote:
I'm not a doctor, but have had cataract surgery in both eyes.
> I just had cataract surgery in my left eye last week, and an
> intraocular lens was placed by the ophthalmologist. I'm having the
> right eye done in a few days. My vision in my left eye, with the
> implanted lens, is excellent. I haven't had it checked yet but I'm
> guessing it's 20/15. Prior to the surgery, it was about 20/200.
It may be too soon to tell, but I hope this isn't bad news. The eye
continues to heal over the first few weeks, and most people experience a
change in vision as the eye changes shape due to healing.
> My question: I believe that the prescription the Doc took for the
> intraocular lenses was done, not by a traditional phoropter (that
> device with the two hundred lenses where you are asked, "which is
> better 1 or 2) but instead was done with a computer controlled device
> that you look into and measurements are taken by the computer. I'm
> guessing that the measurements involve the curvature of the cornea.
Cataract surgery involves eliminating the refraction caused by the lens
inside your eye. There is no way to measure how much this refraction
is, but it is generally so large that ignoring it causes big problems in
vision, thus the IOL. The best that can be done is to measure the
curvature of the cornea and the distance between the cornea and the
retina. Your doctor takes these numbers and plugs them into a formula,
adding a fudge factor based on experience, and any changes due to doctor
decisions or patient requests. This is how the doctor determines the
strength of the IOL to implant. I was lucky, both eyes ended up
perfect. My reading indicates that a reasonable goal is plus or minus
.5D. An optometrist can do much better with a phoropter. However, a
phoropter is useless in determining the strength for the IOL.
> I'm convinced that whatever this device is called, it's accuracy is
> far superior to the conventional phoropter because my vision has never
> been sharper (and I've worn glasses my whole life).
My suspicion is that your vision is so fine, because the cataract was
removed. Based on my experience, this is a major, and welcome,
improvement.
> Does anyone know the name of this device? Thanks for info.
I don't know the name, but it uses sound waves to measure the distance.
I would suggest that at your next appointment, ask the staff to tell you
what your vision is in the left eye. Also, ask the doctor to verify
what I posted, since things change and not every doctor does the surgery
the same.
--
Dan Abel
Petaluma, California USA
dabel@sonic,net
Re: Need to know specific name of computerized phoropter
You may have had your refraction measured with an "autorefractor" which uses
infrared light to measure refraction all the way back to the retina.
Autorefractors are a cheap/easy way to estimate the refraction, but they
aren't yet _more_ accurate than subjective refraction.
As Dan said, if you really _needed_ cataract surgery then by far the biggest
improvement would have been from replacing the cloudy lens. Nobody would
brag about prescribing glasses from an autorefractor.
It may be some time before subjective refraction is surpassed by an
instrument like the autorefractor. technique. The thing is, the doctor isn't
actually doing that test... _you_ are. And no instrument is better at
distinguishing what's sharp for _you_ than _you_.
-MT
"BobKK47" <bkk@uplink,net > wrote in message
news:cb457b83-3034-4b75-a357-4d3d09b92c0e@m1g2000pre.googlegroups,com ...
>I just had cataract surgery in my left eye last week, and an
> intraocular lens was placed by the ophthalmologist. I'm having the
> right eye done in a few days. My vision in my left eye, with the
> implanted lens, is excellent. I haven't had it checked yet but I'm
> guessing it's 20/15. Prior to the surgery, it was about 20/200.
>
> My question: I believe that the prescription the Doc took for the
> intraocular lenses was done, not by a traditional phoropter (that
> device with the two hundred lenses where you are asked, "which is
> better 1 or 2) but instead was done with a computer controlled device
> that you look into and measurements are taken by the computer. I'm
> guessing that the measurements involve the curvature of the cornea.
>
> I'm convinced that whatever this device is called, it's accuracy is
> far superior to the conventional phoropter because my vision has never
> been sharper (and I've worn glasses my whole life).
>
> Does anyone know the name of this device? Thanks for info.
You may have had your refraction measured with an "autorefractor" which uses
infrared light to measure refraction all the way back to the retina.
Autorefractors are a cheap/easy way to estimate the refraction, but they
aren't yet _more_ accurate than subjective refraction.
As Dan said, if you really _needed_ cataract surgery then by far the biggest
improvement would have been from replacing the cloudy lens. Nobody would
brag about prescribing glasses from an autorefractor.
It may be some time before subjective refraction is surpassed by an
instrument like the autorefractor. technique. The thing is, the doctor isn't
actually doing that test... _you_ are. And no instrument is better at
distinguishing what's sharp for _you_ than _you_.
-MT
"BobKK47" <bkk@uplink,net > wrote in message
news:cb457b83-3034-4b75-a357-4d3d09b92c0e@m1g2000pre.googlegroups,com ...
>I just had cataract surgery in my left eye last week, and an
> intraocular lens was placed by the ophthalmologist. I'm having the
> right eye done in a few days. My vision in my left eye, with the
> implanted lens, is excellent. I haven't had it checked yet but I'm
> guessing it's 20/15. Prior to the surgery, it was about 20/200.
>
> My question: I believe that the prescription the Doc took for the
> intraocular lenses was done, not by a traditional phoropter (that
> device with the two hundred lenses where you are asked, "which is
> better 1 or 2) but instead was done with a computer controlled device
> that you look into and measurements are taken by the computer. I'm
> guessing that the measurements involve the curvature of the cornea.
>
> I'm convinced that whatever this device is called, it's accuracy is
> far superior to the conventional phoropter because my vision has never
> been sharper (and I've worn glasses my whole life).
>
> Does anyone know the name of this device? Thanks for info.
Re: Need to know specific name of computerized phoropter
In article <s9CdnePx469hsJzVnZ2dnUVZ_sqinZ2d@giganews,com >,
"Mike Tyner" <mtyner@mindspring,com > wrote:
> You may have had your refraction measured with an "autorefractor" which uses
> infrared light to measure refraction all the way back to the retina.
> Autorefractors are a cheap/easy way to estimate the refraction, but they
> aren't yet _more_ accurate than subjective refraction.
>
> As Dan said, if you really _needed_ cataract surgery then by far the biggest
> improvement would have been from replacing the cloudy lens. Nobody would
> brag about prescribing glasses from an autorefractor.
>
> It may be some time before subjective refraction is surpassed by an
> instrument like the autorefractor. technique. The thing is, the doctor isn't
> actually doing that test... _you_ are. And no instrument is better at
> distinguishing what's sharp for _you_ than _you_.
If you have had lens implants to treat cataracts, why not give control
of phoropter settings (with some professional guidance) to the patient
in order to fit glasses? I have seen the argument presented here that
doing so with accommodation present leads to the patient selecting too
negative a lens. Thus the "is one better than two process" gets used.
With lens implants, that argument becomes fallacious.
Bill
In article <s9CdnePx469hsJzVnZ2dnUVZ_sqinZ2d@giganews,com >,
"Mike Tyner" <mtyner@mindspring,com > wrote:
> You may have had your refraction measured with an "autorefractor" which uses
> infrared light to measure refraction all the way back to the retina.
> Autorefractors are a cheap/easy way to estimate the refraction, but they
> aren't yet _more_ accurate than subjective refraction.
>
> As Dan said, if you really _needed_ cataract surgery then by far the biggest
> improvement would have been from replacing the cloudy lens. Nobody would
> brag about prescribing glasses from an autorefractor.
>
> It may be some time before subjective refraction is surpassed by an
> instrument like the autorefractor. technique. The thing is, the doctor isn't
> actually doing that test... _you_ are. And no instrument is better at
> distinguishing what's sharp for _you_ than _you_.
If you have had lens implants to treat cataracts, why not give control
of phoropter settings (with some professional guidance) to the patient
in order to fit glasses? I have seen the argument presented here that
doing so with accommodation present leads to the patient selecting too
negative a lens. Thus the "is one better than two process" gets used.
With lens implants, that argument becomes fallacious.
Bill
Re: Need to know specific name of computerized phoropter
"Salmon Egg" <SalmonEgg@sbcglobal,net > wrote
> If you have had lens implants to treat cataracts, why not give control
> of phoropter settings (with some professional guidance) to the patient
> in order to fit glasses? I have seen the argument presented here that
> doing so with accommodation present leads to the patient selecting too
> negative a lens. Thus the "is one better than two process" gets used.
> With lens implants, that argument becomes fallacious.
Sure, I do this all the time, especially with cyl axis.
There are difficulties with cyl and sphere because one has to be traded off
against the other and it's my experience that people tend to over-select
cylinder. I do it myself, choosing ~half a diopter more than the
conventional JCC test indicates. And overprescribed cylinder easily causes
headaches.
-MT
>
> Bill
"Salmon Egg" <SalmonEgg@sbcglobal,net > wrote
> If you have had lens implants to treat cataracts, why not give control
> of phoropter settings (with some professional guidance) to the patient
> in order to fit glasses? I have seen the argument presented here that
> doing so with accommodation present leads to the patient selecting too
> negative a lens. Thus the "is one better than two process" gets used.
> With lens implants, that argument becomes fallacious.
Sure, I do this all the time, especially with cyl axis.
There are difficulties with cyl and sphere because one has to be traded off
against the other and it's my experience that people tend to over-select
cylinder. I do it myself, choosing ~half a diopter more than the
conventional JCC test indicates. And overprescribed cylinder easily causes
headaches.
-MT
>
> Bill
Re: Need to know specific name of computerized phoropter
In article <PO2dnVpBqJ7S25_VnZ2dnUVZ_tCrnZ2d@giganews,com >,
"Mike Tyner" <mtyner@mindspring,com > wrote:
> "Salmon Egg" <SalmonEgg@sbcglobal,net > wrote
>
> > If you have had lens implants to treat cataracts, why not give control
> > of phoropter settings (with some professional guidance) to the patient
> > in order to fit glasses? I have seen the argument presented here that
> > doing so with accommodation present leads to the patient selecting too
> > negative a lens. Thus the "is one better than two process" gets used.
> > With lens implants, that argument becomes fallacious.
>
> Sure, I do this all the time, especially with cyl axis.
>
> There are difficulties with cyl and sphere because one has to be traded off
> against the other and it's my experience that people tend to over-select
> cylinder. I do it myself, choosing ~half a diopter more than the
> conventional JCC test indicates. And overprescribed cylinder easily causes
> headaches.
>
This trade-off arises because cylinder and sphere are not independent
functions. Zernike functions are orthogonal and complete. That means
that any wavefront distortion can be be matched in a unique way using
Zernike functions. It does not tell you how many are needed for a
specified accuracy. Thus, sphere (one function) will not be affected by
astigmatism (two functions) and vice versa.
Although I am not familiar with how these wavefront distortions are
measured for eyes, the popularity of lasik and similar procedures is
making matching with Zernike functions more familiar to ophthalmologists
and optometrists. I do not know of a neat optical way to replace
cylinders in a phoropter with the more complex aspherics corresponding
to the Zernike functions for astigmatism.
Bill
In article <PO2dnVpBqJ7S25_VnZ2dnUVZ_tCrnZ2d@giganews,com >,
"Mike Tyner" <mtyner@mindspring,com > wrote:
> "Salmon Egg" <SalmonEgg@sbcglobal,net > wrote
>
> > If you have had lens implants to treat cataracts, why not give control
> > of phoropter settings (with some professional guidance) to the patient
> > in order to fit glasses? I have seen the argument presented here that
> > doing so with accommodation present leads to the patient selecting too
> > negative a lens. Thus the "is one better than two process" gets used.
> > With lens implants, that argument becomes fallacious.
>
> Sure, I do this all the time, especially with cyl axis.
>
> There are difficulties with cyl and sphere because one has to be traded off
> against the other and it's my experience that people tend to over-select
> cylinder. I do it myself, choosing ~half a diopter more than the
> conventional JCC test indicates. And overprescribed cylinder easily causes
> headaches.
>
This trade-off arises because cylinder and sphere are not independent
functions. Zernike functions are orthogonal and complete. That means
that any wavefront distortion can be be matched in a unique way using
Zernike functions. It does not tell you how many are needed for a
specified accuracy. Thus, sphere (one function) will not be affected by
astigmatism (two functions) and vice versa.
Although I am not familiar with how these wavefront distortions are
measured for eyes, the popularity of lasik and similar procedures is
making matching with Zernike functions more familiar to ophthalmologists
and optometrists. I do not know of a neat optical way to replace
cylinders in a phoropter with the more complex aspherics corresponding
to the Zernike functions for astigmatism.
Bill
Re: Need to know specific name of computerized phoropter
On Tue, 8 Apr 2008 13:54:24 -0700 (PDT), BobKK47 <bkk@uplink,net >
wrote:
>I just had cataract surgery in my left eye last week, and an
>intraocular lens was placed by the ophthalmologist. I'm having the
>right eye done in a few days. My vision in my left eye, with the
>implanted lens, is excellent. I haven't had it checked yet but I'm
>guessing it's 20/15. Prior to the surgery, it was about 20/200.
>
>My question: I believe that the prescription the Doc took for the
>intraocular lenses was done, not by a traditional phoropter (that
>device with the two hundred lenses where you are asked, "which is
>better 1 or 2) but instead was done with a computer controlled device
>that you look into and measurements are taken by the computer. I'm
>guessing that the measurements involve the curvature of the cornea.
>
>I'm convinced that whatever this device is called, it's accuracy is
>far superior to the conventional phoropter because my vision has never
>been sharper (and I've worn glasses my whole life).
>
>Does anyone know the name of this device? Thanks for info.
I sure hope it wasn't a Marco 3D-Wave.
Did it look like this? < http :// tinyurl,com /4dyelb>
On Tue, 8 Apr 2008 13:54:24 -0700 (PDT), BobKK47 <bkk@uplink,net >
wrote:
>I just had cataract surgery in my left eye last week, and an
>intraocular lens was placed by the ophthalmologist. I'm having the
>right eye done in a few days. My vision in my left eye, with the
>implanted lens, is excellent. I haven't had it checked yet but I'm
>guessing it's 20/15. Prior to the surgery, it was about 20/200.
>
>My question: I believe that the prescription the Doc took for the
>intraocular lenses was done, not by a traditional phoropter (that
>device with the two hundred lenses where you are asked, "which is
>better 1 or 2) but instead was done with a computer controlled device
>that you look into and measurements are taken by the computer. I'm
>guessing that the measurements involve the curvature of the cornea.
>
>I'm convinced that whatever this device is called, it's accuracy is
>far superior to the conventional phoropter because my vision has never
>been sharper (and I've worn glasses my whole life).
>
>Does anyone know the name of this device? Thanks for info.
I sure hope it wasn't a Marco 3D-Wave.
Did it look like this? < http :// tinyurl,com /4dyelb>
