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Astrid via MedKB.com
medicine forum beginner
Joined: 01 May 2006
Posts: 12
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Mike Tyner
medicine forum Guru
Joined: 24 Mar 2005
Posts: 1299
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 Posted: Sat Jun 24, 2006 8:55 pm Post subject:
Re: Toric CLs
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"ChingoBelle via MedKB.com" <u21384@uwe> wrote
| Quote: | What amount of astigmatism requires toric lenses to be prescribed? Thanks.
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The short answer is 1.00 in the better eye. The long answer is that there is
no short answer.
"Satisfactory" varies by person and by situation. People tolerate
cylindrical blur differently.
If you're nearsighted, you're familiar with the blur that your astigmatism
causes. When you take off your glasses, how well do you see up close? It
takes a lot of astigmatism to reduce vision to disabling levels.
Many times astigmatism is better in one eye, and it becomes the "dominant"
eye so that spherical (non-toric) lenses in _both_ eyes gives "satisfactory"
vision.
Sometimes ordinary soft lenses correct your astigmatism partially, and the
approximation is fine under goggles, water sports, etc. where elsewhere you
could use glasses.
Glasses can be designed to add astigmatism correction over ordinary
spherical contacts, for driving at night or reading the cable guide.
-MT |
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Astrid via MedKB.com
medicine forum beginner
Joined: 01 May 2006
Posts: 12
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| Posted: Sun Jun 25, 2006 5:52 am Post subject:
Re: Toric CLs
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Thank you Mike.
I understood if someone has astigmatism but wears regular (rather than toric)
contacts it's possible to increase the prescription to compensate. How much
real astigmatism could be corrected by an extra -0.25 or -0.50?
You said "It takes a lot of astigmatism to reduce vision to disabling levels"
- what would you call 'a lot'? And lastly, is -0.25 really noticeable?
Thanks!
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Message posted via MedKB.com
http://www.medkb.com/Uwe/Forums.aspx/vision/200606/1 |
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The Reál Bev
medicine forum beginner
Joined: 23 May 2006
Posts: 34
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| Posted: Sun Jun 25, 2006 6:02 am Post subject:
Re: Toric CLs
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ChingoBelle via MedKB.com wrote:
| Quote: | Thank you Mike.
I understood if someone has astigmatism but wears regular (rather than toric)
contacts it's possible to increase the prescription to compensate. How much
real astigmatism could be corrected by an extra -0.25 or -0.50?
You said "It takes a lot of astigmatism to reduce vision to disabling levels"
- what would you call 'a lot'?
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I've got +3 and +5D with -2.25 astigmatism correction. I could drive
with it if I had to, but I couldn't read any of the street signs or
license plates no matter how close I was to them.
Might to be interesting to get +3 and +5 non-toric contacts and then
take up the astigmatism with glasses. Or not.
| Quote: | And lastly, is -0.25 really noticeable?
Thanks!
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--
Cheers, Bev
=============================================
You need only two tools: WD-40 and duct tape.
If it doesn't move and it should, use WD-40.
If it moves and shouldn't, use duct tape. |
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Mike Tyner
medicine forum Guru
Joined: 24 Mar 2005
Posts: 1299
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| Posted: Sun Jun 25, 2006 1:14 pm Post subject:
Re: Toric CLs
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"ChingoBelle via MedKB.com" <u21384@uwe> wrote
| Quote: | I understood if someone has astigmatism but wears regular (rather than
toric)
contacts it's possible to increase the prescription to compensate. How
much
real astigmatism could be corrected by an extra -0.25 or -0.50?
|
If the prescription is -0.75 - 1.00 x 090, this means 0.75 of
nearsightedness and 1.00 D of astigmatism.
The rule of thumb is to take half the cylinder value (-1.00/2) and add it to
the sphere (-0.75 -0.50= -1.25)
| Quote: | You said "It takes a lot of astigmatism to reduce vision to disabling
levels"
- what would you call 'a lot'?
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2.50
And lastly, is -0.25 really noticeable?
No. Nobody makes toric lenses with 0.25 cylinder value, and very few make
0.50. The weakest cylinder value available in torics is usually 0.75.
-MT |
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acemanvx@yahoo.com
medicine forum Guru
Joined: 15 Nov 2005
Posts: 732
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| Posted: Sat Jul 01, 2006 12:19 am Post subject:
Re: Toric CLs
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ChingoBelle via MedKB.com wrote:
Usually at least -.75 to -1.25 for torics. If you have less than -.75
you get regular lens and perhaps a -.25 bump in spherical eqivalent. Up
to -1 cylindar can be corrected fine with soft lens, use -.5 spherical
equivalent. |
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Neil Brooks
medicine forum Guru
Joined: 24 Mar 2005
Posts: 1148
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| Posted: Sat Jul 01, 2006 12:22 am Post subject:
Re: Toric CLs
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On 30 Jun 2006 17:19:30 -0700, acemanvx@yahoo.com wrote:
| Quote: |
ChingoBelle via MedKB.com wrote:
What amount of astigmatism requires toric lenses to be prescribed? Thanks.
--
Message posted via MedKB.com
http://www.medkb.com/Uwe/Forums.aspx/vision/200606/1
Usually at least -.75 to -1.25 for torics. If you have less than -.75
you get regular lens and perhaps a -.25 bump in spherical eqivalent. Up
to -1 cylindar can be corrected fine with soft lens, use -.5 spherical
equivalent.
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Ace,
Can you remember the name of the particular *class* in optometry
school where they tought you this??
Thanks. |
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Neil Brooks
medicine forum Guru
Joined: 24 Mar 2005
Posts: 1148
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| Posted: Sat Jul 01, 2006 12:26 am Post subject:
Re: Toric CLs
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On Sat, 01 Jul 2006 00:22:55 GMT, Neil Brooks <neil0502@yahoo.com>
wrote:
| Quote: | On 30 Jun 2006 17:19:30 -0700, acemanvx@yahoo.com wrote:
ChingoBelle via MedKB.com wrote:
What amount of astigmatism requires toric lenses to be prescribed? Thanks.
--
Message posted via MedKB.com
http://www.medkb.com/Uwe/Forums.aspx/vision/200606/1
Usually at least -.75 to -1.25 for torics. If you have less than -.75
you get regular lens and perhaps a -.25 bump in spherical eqivalent. Up
to -1 cylindar can be corrected fine with soft lens, use -.5 spherical
equivalent.
Ace,
Can you remember the name of the particular *class* in optometry
school where they tought you this??
Thanks.
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"taught"
That should be "taught."
Substance of the post is still valid  |
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