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Kyle
medicine forum beginner
Joined: 25 Mar 2005
Posts: 22
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 Posted: Sat Oct 29, 2005 6:12 am Post subject:
Optical Coherence Tomography question
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Hi,
When a doctor uses OCT. Does the machine "default" to scan the entire
360 degree retinal surface of the eye from the peripheral or edge to
the center or macula. Or does he has to input regions to scan such as
macula or even optic disc or selected retinal
locations??
Kyle |
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EyeTech
medicine forum beginner
Joined: 31 Oct 2005
Posts: 31
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| Posted: Mon Oct 31, 2005 4:56 am Post subject:
Re: Optical Coherence Tomography question
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He/she (or his tech) scans a particular area. Usually the optic disc (to
measure cupping or the retina nerve fiber layer) or the macula. Depends on
what he/she is looking for.
"Kyle" <kyletaylorny@yahoo.com> wrote in message
news:1130566361.304786.137550@z14g2000cwz.googlegroups.com...
| Quote: | Hi,
When a doctor uses OCT. Does the machine "default" to scan the entire
360 degree retinal surface of the eye from the peripheral or edge to
the center or macula. Or does he has to input regions to scan such as
macula or even optic disc or selected retinal
locations??
Kyle
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Kyle
medicine forum beginner
Joined: 25 Mar 2005
Posts: 22
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| Posted: Mon Oct 31, 2005 9:27 am Post subject:
Re: Optical Coherence Tomography question
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EyeTech wrote:
| Quote: | He/she (or his tech) scans a particular area. Usually the optic disc (to
measure cupping or the retina nerve fiber layer) or the macula. Depends on
what he/she is looking for.
|
I see. In the case of cupping, isn't it that one can measure
the cup-to-disc ratio by noting how big is the optic disk and
the cupping. So what do you mean measuring cupping in particular?
Is there any chance (even 0.01%) or no matter how tiny as it may seem
that the laser can damage the rods and cones.
Also it is possible to scan the entire retinal surface from the
macula to optic disk to peripheral portions in one sitting. How
long would this take?
Tnx.
Kyle
| Quote: |
"Kyle" <kyletaylorny@yahoo.com> wrote in message
news:1130566361.304786.137550@z14g2000cwz.googlegroups.com...
Hi,
When a doctor uses OCT. Does the machine "default" to scan the entire
360 degree retinal surface of the eye from the peripheral or edge to
the center or macula. Or does he has to input regions to scan such as
macula or even optic disc or selected retinal
locations??
Kyle
|
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|
| Back to top |
|
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EyeTech
medicine forum beginner
Joined: 31 Oct 2005
Posts: 31
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| Posted: Mon Oct 31, 2005 1:18 pm Post subject:
Re: Optical Coherence Tomography question
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"Kyle" <kyletaylorny@yahoo.com> wrote in message
news:1130750857.124088.284420@g14g2000cwa.googlegroups.com...
| Quote: |
EyeTech wrote:
He/she (or his tech) scans a particular area. Usually the optic disc (to
measure cupping or the retina nerve fiber layer) or the macula. Depends
on
what he/she is looking for.
I see. In the case of cupping, isn't it that one can measure
the cup-to-disc ratio by noting how big is the optic disk and
the cupping. So what do you mean measuring cupping in particular?
|
The doctor does measure by estimating the ratio, but using the OCT actually
gives a 3 D image with 6 different views. With the OCT you can actually see
the cupping from the back of the eye (optic nerve) towards the retina. The
retina nerve fiber layer scans around the optic disc and measures the
thickness of the nerve layers to check for thinning.
| Quote: |
Is there any chance (even 0.01%) or no matter how tiny as it may seem
that the laser can damage the rods and cones.
|
I haven't read up that much on risks, but I believe it is more like
ultrasound. I will check the manual and get back to you.
| Quote: |
Also it is possible to scan the entire retinal surface from the
macula to optic disk to peripheral portions in one sitting. How
long would this take?
|
We have only scanned the optic disk and macula. This can be done in one
setting. It is a very quick procedure (less than 5 minutes per eye), unless
the patient has trouble with fixation. The periphery isn't scanned, at
least not as far as I know (but I'll look into it too).
| Quote: |
Tnx.
Kyle
"Kyle" <kyletaylorny@yahoo.com> wrote in message
news:1130566361.304786.137550@z14g2000cwz.googlegroups.com...
Hi,
When a doctor uses OCT. Does the machine "default" to scan the entire
360 degree retinal surface of the eye from the peripheral or edge to
the center or macula. Or does he has to input regions to scan such as
macula or even optic disc or selected retinal
locations??
Kyle
|
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| Back to top |
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Dr. Leukoma
medicine forum Guru
Joined: 30 Apr 2005
Posts: 1283
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| Posted: Mon Oct 31, 2005 1:49 pm Post subject:
Re: Optical Coherence Tomography question
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EyeTech wrote:
| Quote: | I haven't read up that much on risks, but I believe it is more like
ultrasound. I will check the manual and get back to you.
|
The OCT is not an ultrasonic device, but utilizes a beam of light in
the 700-800 nm range. While I have not had it performed on me, I have
observed that patients have not displayed any signs of discomfort. The
peak senstivity of the rods is in the 500-600 nm region.
DrG |
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gudrun17
medicine forum beginner
Joined: 25 May 2005
Posts: 41
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| Posted: Mon Oct 31, 2005 6:18 pm Post subject:
Re: Optical Coherence Tomography question
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There must
EyeTech wrote:
| Quote: | "Kyle" <kyletaylorny@yahoo.com> wrote in message
news:1130750857.124088.284420@g14g2000cwa.googlegroups.com...
EyeTech wrote:
He/she (or his tech) scans a particular area. Usually the optic disc (to
measure cupping or the retina nerve fiber layer) or the macula. Depends
on
what he/she is looking for.
I see. In the case of cupping, isn't it that one can measure
the cup-to-disc ratio by noting how big is the optic disk and
the cupping. So what do you mean measuring cupping in particular?
The doctor does measure by estimating the ratio, but using the OCT actually
gives a 3 D image with 6 different views. With the OCT you can actually see
the cupping from the back of the eye (optic nerve) towards the retina. The
retina nerve fiber layer scans around the optic disc and measures the
thickness of the nerve layers to check for thinning.
Is there any chance (even 0.01%) or no matter how tiny as it may seem
that the laser can damage the rods and cones.
I haven't read up that much on risks, but I believe it is more like
ultrasound. I will check the manual and get back to you.
Also it is possible to scan the entire retinal surface from the
macula to optic disk to peripheral portions in one sitting. How
long would this take?
We have only scanned the optic disk and macula. This can be done in one
setting. It is a very quick procedure (less than 5 minutes per eye), unless
the patient has trouble with fixation. The periphery isn't scanned, at
least not as far as I know (but I'll look into it too).
|
My doctor said OCT measured 16 different sectors of the retinal nerve
fiber layer. Is that what you mean by different views? My HRT's have
measured cup to disk ratio but I didn't know OCT would do this. All my
doctor mentioned was thickness of the nerve fiber layer in each sector,
but presumably that's all he was looking for. When my husband had OCT
it was to examine subretinal fluid.
-Gudrun |
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Kyle
medicine forum beginner
Joined: 25 Mar 2005
Posts: 22
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| Posted: Tue Nov 01, 2005 12:00 am Post subject:
Re: Optical Coherence Tomography question
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EyeTech wrote:
| Quote: | "Kyle" <kyletaylorny@yahoo.com> wrote in message
news:1130750857.124088.284420@g14g2000cwa.googlegroups.com...
EyeTech wrote:
He/she (or his tech) scans a particular area. Usually the optic disc (to
measure cupping or the retina nerve fiber layer) or the macula. Depends
on
what he/she is looking for.
I see. In the case of cupping, isn't it that one can measure
the cup-to-disc ratio by noting how big is the optic disk and
the cupping. So what do you mean measuring cupping in particular?
The doctor does measure by estimating the ratio, but using the OCT actually
gives a 3 D image with 6 different views. With the OCT you can actually see
the cupping from the back of the eye (optic nerve) towards the retina. The
retina nerve fiber layer scans around the optic disc and measures the
thickness of the nerve layers to check for thinning.
|
Is it possible to have thin retina nerve layer yet the nerve fiber
going to the optic disk is normal?? For example. A person has an
average cup to ratio of 0.3. Is it possible the nerve layer beneath
the retina is thin yet the nerve fiber going into the optic disk
is normal?
kyle
| Quote: |
Is there any chance (even 0.01%) or no matter how tiny as it may seem
that the laser can damage the rods and cones.
I haven't read up that much on risks, but I believe it is more like
ultrasound. I will check the manual and get back to you.
Also it is possible to scan the entire retinal surface from the
macula to optic disk to peripheral portions in one sitting. How
long would this take?
We have only scanned the optic disk and macula. This can be done in one
setting. It is a very quick procedure (less than 5 minutes per eye), unless
the patient has trouble with fixation. The periphery isn't scanned, at
least not as far as I know (but I'll look into it too).
Tnx.
Kyle
"Kyle" <kyletaylorny@yahoo.com> wrote in message
news:1130566361.304786.137550@z14g2000cwz.googlegroups.com...
Hi,
When a doctor uses OCT. Does the machine "default" to scan the entire
360 degree retinal surface of the eye from the peripheral or edge to
the center or macula. Or does he has to input regions to scan such as
macula or even optic disc or selected retinal
locations??
Kyle
|
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| Back to top |
|
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EyeTech
medicine forum beginner
Joined: 31 Oct 2005
Posts: 31
|
| Posted: Wed Nov 02, 2005 2:32 am Post subject:
Re: Optical Coherence Tomography question
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|
Kyle:
Your question about risks, the manual was pretty vague, I read a portion of
it today (meant to bring it home, but forgot it), but to summarize you would
have to scan the exact same portion of the retina for a long period every
day to cause any risk. No percentages were given. The OCT is not
ultrasound, it is like ultrasound in that it measures the light reflections,
whereas the ultrasound measures sound reflections.
It is only used for the portions previously discussed (not the periphery).
I don't know if there are any "off label" uses.
When we measure the RNFL (retina nerve fiber layer) it measures 360 degrees
around the optic nerve. We are usually checking for thinning of the RNFL
caused by glaucoma. We also do the ON (optic nerve) scan to check the
cupping at that time. I'm not sure what you're asking in your last posted
question regarding a thin retina nerve fiber layer with a normal nerve fiber
going into the optic disk. That would be a question for your doctor to
answer. If you or a family member has a question about test results - the
best thing to do is ask. We have patients who even bring a list of
questions in with them so they don't forget to ask them all. It's your
right to be informed.
If indicated we scan the macula. Usually done in patients who have macular
degeneration, macular edema, macular hole, macular pucker, premacular
fibrosis, the list goes on. It is very sensitive and can detect early
holes, fluid (edema), holes, etc..
"Kyle" <kyletaylorny@yahoo.com> wrote in message
news:1130803205.736341.140490@o13g2000cwo.googlegroups.com...
| Quote: |
EyeTech wrote:
"Kyle" <kyletaylorny@yahoo.com> wrote in message
news:1130750857.124088.284420@g14g2000cwa.googlegroups.com...
EyeTech wrote:
He/she (or his tech) scans a particular area. Usually the optic disc
(to
measure cupping or the retina nerve fiber layer) or the macula.
Depends
on
what he/she is looking for.
I see. In the case of cupping, isn't it that one can measure
the cup-to-disc ratio by noting how big is the optic disk and
the cupping. So what do you mean measuring cupping in particular?
The doctor does measure by estimating the ratio, but using the OCT
actually
gives a 3 D image with 6 different views. With the OCT you can actually
see
the cupping from the back of the eye (optic nerve) towards the retina.
The
retina nerve fiber layer scans around the optic disc and measures the
thickness of the nerve layers to check for thinning.
Is it possible to have thin retina nerve layer yet the nerve fiber
going to the optic disk is normal?? For example. A person has an
average cup to ratio of 0.3. Is it possible the nerve layer beneath
the retina is thin yet the nerve fiber going into the optic disk
is normal?
kyle
Is there any chance (even 0.01%) or no matter how tiny as it may seem
that the laser can damage the rods and cones.
I haven't read up that much on risks, but I believe it is more like
ultrasound. I will check the manual and get back to you.
Also it is possible to scan the entire retinal surface from the
macula to optic disk to peripheral portions in one sitting. How
long would this take?
We have only scanned the optic disk and macula. This can be done in one
setting. It is a very quick procedure (less than 5 minutes per eye),
unless
the patient has trouble with fixation. The periphery isn't scanned, at
least not as far as I know (but I'll look into it too).
Tnx.
Kyle
"Kyle" <kyletaylorny@yahoo.com> wrote in message
news:1130566361.304786.137550@z14g2000cwz.googlegroups.com...
Hi,
When a doctor uses OCT. Does the machine "default" to scan the
entire
360 degree retinal surface of the eye from the peripheral or edge to
the center or macula. Or does he has to input regions to scan such
as
macula or even optic disc or selected retinal
locations??
Kyle
|
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| Back to top |
|
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EyeTech
medicine forum beginner
Joined: 31 Oct 2005
Posts: 31
|
| Posted: Wed Nov 02, 2005 2:41 am Post subject:
Re: Optical Coherence Tomography question
|
|
|
"gudrun17" <yngver@aol.com> wrote in message
news:1130782694.039232.167270@o13g2000cwo.googlegroups.com...
| Quote: | There must
EyeTech wrote:
"Kyle" <kyletaylorny@yahoo.com> wrote in message
news:1130750857.124088.284420@g14g2000cwa.googlegroups.com...
EyeTech wrote:
He/she (or his tech) scans a particular area. Usually the optic disc
(to
measure cupping or the retina nerve fiber layer) or the macula.
Depends
on
what he/she is looking for.
I see. In the case of cupping, isn't it that one can measure
the cup-to-disc ratio by noting how big is the optic disk and
the cupping. So what do you mean measuring cupping in particular?
The doctor does measure by estimating the ratio, but using the OCT
actually
gives a 3 D image with 6 different views. With the OCT you can actually
see
the cupping from the back of the eye (optic nerve) towards the retina.
The
retina nerve fiber layer scans around the optic disc and measures the
thickness of the nerve layers to check for thinning.
Is there any chance (even 0.01%) or no matter how tiny as it may seem
that the laser can damage the rods and cones.
I haven't read up that much on risks, but I believe it is more like
ultrasound. I will check the manual and get back to you.
Also it is possible to scan the entire retinal surface from the
macula to optic disk to peripheral portions in one sitting. How
long would this take?
We have only scanned the optic disk and macula. This can be done in one
setting. It is a very quick procedure (less than 5 minutes per eye),
unless
the patient has trouble with fixation. The periphery isn't scanned, at
least not as far as I know (but I'll look into it too).
My doctor said OCT measured 16 different sectors of the retinal nerve
fiber layer. Is that what you mean by different views? My HRT's have
measured cup to disk ratio but I didn't know OCT would do this. All my
doctor mentioned was thickness of the nerve fiber layer in each sector,
but presumably that's all he was looking for. When my husband had OCT
it was to examine subretinal fluid.
-Gudrun
|
The retinal nerve fiber layer and the macula scans both scan 6 different
angles. It is not the same as the sectors your doctor refers to. (Maybe
sectors are layers of the retina??) By scanning in different angles we can
then choose to scan just one particular angle at a higher resolution to get
a better view of something, like subretinal fluid.
The optic nerve scan makes one 360 degree scan around the nerve. |
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Don W
medicine forum addict
Joined: 26 May 2005
Posts: 90
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| Posted: Sun Nov 06, 2005 4:36 pm Post subject:
Re: Optical Coherence Tomography question
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.. If you or a family member has a question about test results - the
| Quote: | best thing to do is ask. We have patients who even bring a list of
questions in with them so they don't forget to ask them all. It's your
right to be informed.
|
Just wondering... how is that right defined? Sometimes it's very difficult
to even buttonhole the doc.
Don W.. |
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EyeTech
medicine forum beginner
Joined: 31 Oct 2005
Posts: 31
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| Posted: Mon Nov 07, 2005 4:31 am Post subject:
Re: Optical Coherence Tomography question
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Maybe I should have said "your right and your responsibility to stay
informed about your health." Doctors do have a huge demand on their time,
but for the most part if you ask questions they answer them. Some patients
want the information in the simplest terms possible, others want more
complex. Either way, it's hard for the doctor to read the patient's level
of understanding in a short time while being pushed for time and making a
diagnosis (and sometimes determining a treatment plan). So slow things down
and ask questions. It's your time. When he walks in the room and the door
closes behind him, he's on your time. I hate to say this, but if your
doctor isn't willing or able to take time to explain things to you or answer
your questions, maybe you need a different provider. The doctor I work for
is guilty of running behind schedule (who isn't), but for the most part, by
the time he's done with the patients they don't mind, they feel they were
treated right and not rushed through just because he was behind.
"Don W" <dwilgus@prodigy.net> wrote in message
news:2iqbf.6535$Kv.5422@newssvr22.news.prodigy.net...
| Quote: | . If you or a family member has a question about test results - the
best thing to do is ask. We have patients who even bring a list of
questions in with them so they don't forget to ask them all. It's your
right to be informed.
Just wondering... how is that right defined? Sometimes it's very
difficult to even buttonhole the doc.
Don W..
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