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Question: What is “with the rule” astigmatism?
Answer: This is when the axis of the positive cylinder in a pair of glasses is oriented at 90 degrees.
“With the rule” astigmatism is typically seen in children, while “against the rule astigmatism” is seen in older eyes.
Comments and Feedback
12 Comments
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Very short, concise n yet ridicolously simple !!!
I ilke this website
although i m a trainee in masters ophthalmology program..i found this website very helpful
Comment by hajar — April 28, 2009 @ 11:14 am
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Simplicity!
Brilliant work:)
Comment by rozana mahajuodeen — September 16, 2009 @ 3:35 am
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“” What is “with the rule” astigmatism?
Answer: This is when the axis of the positive cylinder in a pair of glasses is oriented at 90 degrees.”"
THIS IS Wrong
The correct Answer:
This is when the axis of the positive cylinder in a pair of glasses is oriented at 180 degrees.
or
Answer: This is when the MERIDIAN of the positive cylinder in a pair of glasses is oriented at 90 degrees.
Comment by Refractive Surgeon — January 30, 2011 @ 5:47 am
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“The correct Answer:
This is when the axis of the positive cylinder in a pair of glasses is oriented at 180 degrees.
or
Answer: This is when the MERIDIAN of the positive cylinder in a pair of glasses is oriented at 90 degrees.”
I may just be an optometry student, but the author is correct. With-the-rule astigmatism means that the EYE is steeper in the vertical meridian (more plus).
To correct this astigmatism in a pair of eyeglasses, one would need to add more plus to the horizontal meridian or add more minus to the vertical meridian. The MERIDIAN of a positive cylinder lens would be at 180 degrees. The CYLINDER of this same positive lens is 90 degrees.
Comment by Optometry Student — March 13, 2011 @ 7:30 pm
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I must disagree with “Refractive Surgeon” and support both the author and “Optometry Student” in this matter.
If the eye is more steeply curved in the vertical meridian then this will require a more negative prescription in order to place the focal point on the retina.
With regard to Cylinder lenses (where there is no power along the axis), if working in positive cylinder then the axis would be at 90 degrees.
I must congratulate the author on a fantastic website and book. Very simply set out with great explanations. Well done.
Comment by Optometrist — April 6, 2011 @ 5:08 pm
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pressure of lid compresses the eye ball vertically.cornea becomes steeper vertically ie.the radius of curvature decreases in the vertical meredian.so a sheet of rays in a vertical plane will be focussed in front of retina producing a horizontal line in front of retina.this is the error :and to rectify this we will need diverging lenses which will diverge rays in the vertical plane ie.90 degree and will have its axis at 180 degrees.ie minus cyl at180 degree.
one must understand what is a cylindrical lens first
Comment by debashis dutta — April 21, 2011 @ 1:43 pm
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I am not an optometrist but as an engineer I know that defining AGR as exactly 90 degrees makes no sense. It seems to me it should be a range, maybe 75 to 105? And as a volunteer optometric assistant, I have seen a number of Hispanic children with AGR astigmatism.
Comment by Eldon Steelman — June 1, 2011 @ 4:52 pm
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which type of patient will be more symptomatic with the rule or against the rule astigmatism.why?
Comment by Dr M anwar — September 7, 2011 @ 11:16 pm
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Very simply put in the site.
The point to remember is:
WTR -> -ve Cylinder axis 180 (or) +ve cylinder axis 90
ATR -> -ve Cylinder axis 90 (or) +ve cylinder axis 180
(the steeper corneal meridian is opposite that of the AXIS of the correcting minus cylinder and same as that of the POWER of the correcting minus cylinder)
Comment by Renjini — October 1, 2011 @ 1:42 am
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im very much confused about with the rule astigmatism and against the rule astigmatism…each n everytime i hav to think for it….
Comment by sita — December 6, 2011 @ 1:00 am
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@dr.m anwar.. i think against the rule astigmatism will hav more problem then with the rule astigmatism…
Comment by sita — December 6, 2011 @ 1:03 am
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