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Science Forum Index » Medicine - Vision Forum » Lenses
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| Cathy via MedKB.com |
 Posted: Sun Jun 03, 2007 12:01 pm |
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Guest
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My friend and I have similar prescriptons c-.275 yet hers look much stronger
so I presume it is the lens material. Her's aren't thicker but we both think
things look more intense through hers. Is it the lenses or the frame that
make the difference and is it usual that the same strength of prescription
can sometimes look stronger?
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| Salmon Egg |
| Posted: Sun Jun 03, 2007 12:16 pm |
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On 6/3/07 10:01 AM, in article 7327b13c3732e@uwe, "Cathy via MedKB.com"
<u12444@uwe> wrote:
Quote: My friend and I have similar prescriptons c-.275 yet hers look much stronger
so I presume it is the lens material. Her's aren't thicker but we both think
things look more intense through hers. Is it the lenses or the frame that
make the difference and is it usual that the same strength of prescription
can sometimes look stronger?
It is very difficult to understand what you are getting at. You are using
English teacher impressionistic metaphors rather than geeky but precise tech
speak.
Could it be that your friend's lenses are antireflection coated? That would
make things seen through her lenses appear a bit brighter and sharper than
seen through yours.
Bill
-- Support the troops. Impeach Bush. Oh, I forgot about Cheney. |
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| michael toulch |
| Posted: Sun Jun 03, 2007 7:42 pm |
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On Jun 3, 1:01 pm, "Cathy via MedKB.com" <u12444@uwe> wrote:
Quote: My friend and I have similar prescriptons c-.275 yet hers look much stronger
so I presume it is the lens material. Her's aren't thicker but we both think
things look more intense through hers. Is it the lenses or the frame that
make the difference and is it usual that the same strength of prescription
can sometimes look stronger?
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Message posted viahttp://www.medkb.com
you say similar prescriptions but there may be more difference than
you think (astigmatism eg.). |
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| Cathy via MedKB.com |
| Posted: Mon Jun 04, 2007 3:53 pm |
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Guest
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michael toulch wrote:
Quote: My friend and I have similar prescriptons c-.275 yet hers look much stronger
so I presume it is the lens material. Her's aren't thicker but we both think
[quoted text clipped - 4 lines]
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Message posted viahttp://www.medkb.com
you say similar prescriptions but there may be more difference than
you think (astigmatism eg.).
How much difference would that make. I have -.5 astigmatism. She says she is -
2.50 and wears -2.75 contacts.
How does astigmatism change how lenses look? Is it possible to tell if there
is astigmatism?
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| Guest |
| Posted: Fri Jun 08, 2007 3:19 am |
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On 4 Jun, 22:53, "Cathy via MedKB.com" <u12444@uwe> wrote:
Quote:
How much difference would that make. I have -.5 astigmatism. She says she is -
2.50 and wears -2.75 contacts.
How does astigmatism change how lenses look? Is it possible to tell if there
is astigmatism?
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Hi
I find even 0.25 makes a noticeable difference for me. To find out of
there is astigmatism:
1. Hold your glasses out in front of you and look through one lens
with one eye.
2. Rotate them so that the lens turns through 90 degrees clockwise
then anticlockwise still looking through the lens. The frames will be
vertical (like this : ) instead of horizontal ( . . )
3. If there is astigmatism you will see the image getting narrower or
fatter as you turn.
If you have the prescription then the astigmatism will be a second
power figure followed by x A
where A is the axis between 1 and 180 degrees. So if the prescription
for one eye is -2.50 -0.50 x 180 you have 0.5 dioptres of astigmatism
in that eye.
There is another format for writing the prescription like this:
-3.00 +0.50 x 90 which is exactly the same prescription just a
different way of writing it (seems to be less common though these
days, at least in the UK).
Richard |
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| Cathy via MedKB.com |
| Posted: Sun Jun 10, 2007 1:29 am |
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Thanks Richard. I'll try that.
I wondered whether then, if i can do that and see it, whether other people
can see astigmatism in that way, and whether difference types of lenses (ie 1.
67 etc) create a different impression of how strong they are?
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Message posted via MedKB.com
http://www.medkb.com/Uwe/Forums.aspx/vision/200706/1 |
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