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Science Forum Index » Medicine - Vision Forum » Angle of astigmatism - does it make a difference?
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| Katy via MedKB.com |
 Posted: Tue Dec 26, 2006 5:16 am |
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I read that dependent on the angle of the astigmatism the same amount can be
worse in two people. Which is the worst angle? I've had -0.50 at either 140
or 150 for the last 5 years and this eye is more difficult to correct than
the other, could that be the reason?
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| Charles |
| Posted: Tue Dec 26, 2006 11:10 am |
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Katy via MedKB.com wrote:
Quote: I read that dependent on the angle of the astigmatism the same amount
can be worse in two people. Which is the worst angle? I've had
-0.50 at either 140 or 150 for the last 5 years and this eye is more
difficult to correct than the other, could that be the reason?
Not a doctor, but I think maybe what is being said is that 0/180
astigmatism seems to be subjectively more tolerable to people compared
to 90 degree astigmatism. Up/down blur is probably easier to read
through compared to left/right blur. I think it's also true that a
person can "squint through" 0/180 astigmatism to some extent and you
can't with 90.
140 is getting pretty close to half-way between those cases.
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| LarryDoc |
| Posted: Tue Dec 26, 2006 3:04 pm |
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In article <6b548ae436fcc@uwe>, "Katy via MedKB.com" <u12444@uwe>
wrote:
Quote: I read that dependent on the angle of the astigmatism the same amount can be
worse in two people. Which is the worst angle? I've had -0.50 at either 140
or 150 for the last 5 years and this eye is more difficult to correct than
the other, could that be the reason?
Not likely, although "difficult to correct" doesn't really tell us much
about your issue.
Astig (minus) axis 90 generally produces more noticeable blur than 180.
..50 is fairly small. If it associated with hyperopia, that may be a
vision issue. If combined with a moderate amount of myopia, then
perhaps a miniscule effect. You have oblique angle astigmatism. If you
have the same in the opposite direction in the other eye, uncorrected,
the combined effect is close to zero. If only in one eye with no other
optical correction in either eye, then a potential issue with using
spectacle correction comfortably.
Conclusion here: there's not enough subjective information or optical
data to have a meaningful discussion specific to you. But to answer the
subject of your post: Yes!
LB, O.D. |
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| odtobe |
| Posted: Wed Dec 27, 2006 2:22 pm |
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Astigmatism that uses minus cyl to correct (what optometrist's write
their Rx in) in the 180 meridian, or near 180, is more tolerable than
any others. Second would be in the 90 meridian, or near. Lastly would
be oblique astigmatism, like you have, between 30-60, and between
150-120. The rationalle for this is the types of distortion you get
from each lens, and what people are viewing the most, letters or typed
print. The cyl in the 180 stretches the letters in the vertical
direction, while cyl in the 90 stretches letters in the horizontal
direction, both easier to adapt to than having the letters stretched to
some oblique angle. Since most of our language has several vertically
biased letters like "l", "t", "h", and others the distortions don't
change the way the letters look very much, having a shorter adaptation
time than obliquely oriented cyl correction.
LarryDoc wrote:
Quote: In article <6b548ae436fcc@uwe>, "Katy via MedKB.com" <u12444@uwe
wrote:
I read that dependent on the angle of the astigmatism the same amount can be
worse in two people. Which is the worst angle? I've had -0.50 at either 140
or 150 for the last 5 years and this eye is more difficult to correct than
the other, could that be the reason?
Not likely, although "difficult to correct" doesn't really tell us much
about your issue.
Astig (minus) axis 90 generally produces more noticeable blur than 180.
.50 is fairly small. If it associated with hyperopia, that may be a
vision issue. If combined with a moderate amount of myopia, then
perhaps a miniscule effect. You have oblique angle astigmatism. If you
have the same in the opposite direction in the other eye, uncorrected,
the combined effect is close to zero. If only in one eye with no other
optical correction in either eye, then a potential issue with using
spectacle correction comfortably.
Conclusion here: there's not enough subjective information or optical
data to have a meaningful discussion specific to you. But to answer the
subject of your post: Yes!
LB, O.D. |
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