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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.


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

Brilliant work:)

Comment by rozana mahajuodeen — September 16, 2009

“” 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.””


The correct Answer:
This is when the axis of the positive cylinder in a pair of glasses is oriented at 180 degrees.
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

“The correct Answer:
This is when the axis of the positive cylinder in a pair of glasses is oriented at 180 degrees.
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

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

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

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

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

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

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

@dr.m anwar.. i think against the rule astigmatism will hav more problem then with the rule astigmatism…

Comment by sita — December 6, 2011

really very interactive.

Comment by ria cevangelista — January 13, 2012

with the rule- the steeper curvature is at 90 degrees. This means that there is positive power at 90, and negative power at 180.

against the rule- the steeper curvature is at 180. This means that positive power is at 180, and negative power at 90.

it should also be noted that there is a 30 degree range of power for each type. Meaning, for with the rule, you can be positive between 60 and 120, and minus between 30 and 150.

Comment by matthew poreda — February 8, 2012

I am also an optometry student.I like this website very much.Many students confused between meridian and axis.when correcting the refraction by a cylindrical lens,we have to know they(meridian and axis)are opposite.If we want to give positive in vertical meridian,we will have to choose positive 180 degree.

Comment by T H winmyint — March 4, 2012

The confusion is nobody works in plus cyl anymore. Thats old school.

With the rule : the -ve cyl is at 180,

Against the rule : the -ve cyl is at 90.

Usually having astigmatism at these axis the patients can cope its when they are oblique they have problems.

Comment by Pre- reg optometrist — March 14, 2012

+ cyl is not old school. Ophthalmologists typically work in + cyl. Optom works in – cyl.

Nothing wrong with that. There is a reason for each occupation to use their method.

Ophthalmic surgeons use + cyl as that is where we make the corneal incisions in cataract surgery if we intend to correct (partly) the astigmatism.

Comment by KC — March 26, 2012

Also “Refractive Surgeon” above – you are wrong. The Author is correct.

Don’t call yourself a Refractive Surgeon and reflect badly on your colleagues.

Comment by KC — March 26, 2012

With the rule astigmatism: The cornea is squeezed from above and below by the lids. This creates astigmatism on the cornea with the axis of the positive cylinder at 180° but the power of the positive cylinder at 90°. It is corrected by prescribing glasses with negative cylinder, axis 180° (power at 90°), or positive cylinder, axis 90° (power at 180°).

Comment by Ophthalmologist — April 6, 2012

still confuse

Comment by kyzt — May 25, 2012

i think we found the the conclution from all above me. And thanks for the author, this is very helpfull

Comment by optician — June 3, 2012

Great photo that made me understand it easily…….Thanks your website has helped me a lot studying ophthalmology

Comment by G. Williams — June 6, 2012

I’m confused. I’m 30yo and I got an prescription from my opthamologist that is -1.00 cylinder, 90 axis. But I read that opthamologists uses positive numbers instead. If I convert this to a positive cylinder, would I have with-the-rule astigmatism, or against-the rule (maybe I am too old to have with-the-rule astig, but too young to have against-the-rule?)

Comment by Ann — June 11, 2012

The comments are generally correct but the diagram at the top is incorrect. “With the rule” has the cylinder axis horizontally and the steep curve vertically – opposite to the diagram labelling.


Comment by eyesurgeon — July 6, 2012

Sorry eyesurgeon … as already mentioned several times on this page, the author AND the illustration is correct.

You are confusing the drawing of the GLASSES (located to the left of the little kid) with the drawing of the CORNEAL STEEPNESS (drawn on the kid/adult’s eyeballs themselves).

The definition of “with the rule” talks about the GLASSES. The cartoon people are simply a mneumonic to understand the actual CORNEAL steepnesses involved. EVERYTHING is correct in the illustration.

As an “eye surgeon” you really ought to know this. After all … most elderly with cataracts have against-the-rule astigmatism (the old man in this drawing). This means that their CORNEA (not glasses) are steep along the 180 meridian (like in the illustration of the old man). If you create a temporal incision, this should flatten out this horizontal steepness and help a little with their astigmatism.

Comment by Tom — July 7, 2012

There is no power along the AXIS of the cylindrical lens because they are bounded on each side by plane surfaces only. The maximum power for the cylindrical lens is along the plane perpendicular to that of the AXIS which is called the MERIDIAN.

Hence in WTR Astigmatism, where the cornea has a great convexity in its vertical plane, we must counteract that high positive power of cornea with negative power in the vertical position. So if we want to orient a negative cylinder such that it counteracts the vertical positivity, its MERIDIAN should be at 90 degrees and hence its AXIS at 180 degrees. But we prescribe cylindrical lens denoting the orientation of its AXIS.

Many books on Ophthalmology did not explain what AXIS and MERIDIAN are. Indeed astigmatism is a bit tougher concept to understand initially.
I think my explanation is right!

OPHTHOBOOK website is a boon!!!

Comment by NARAYANEE RAJASEKARAN — July 13, 2012

With respect to (+) or (-) cyl . . . refracting really doesn’t make a difference if you refract in plus or minus cyl. Doesn’t matter if your make corneal or LRI based on plus or minus cyl . . . as long as you realized WHAT it is you’re doing. Put a lens clock on any lens and you can read it in plus or minus cyl. Depends on your frame of reference. Same with a lenometer. They key is understanding WHERE the power is (90 degrees from the axis), be it plus or minus from the base sphere power.

As for the question which (if any) cyl is easiest to deal with my experience is this: Oblique is most difficult to adapt to. With the rule (plano-1.00×180) is probably the easiest to adapt to because you can squint and ‘cover’ the meridian of the power, leaving the horizontal meridian as essentially plano. This, of course, assumes no spherical power. If the patient had a script of +3.00-3.00×180 squinting would leave +3.00 and ‘cut out’ the plano vertical meridian. Oblique cyl is bad no matter how it comes. No noticed differences between [OD: 135 OS: 45] vs [OD: 45 OS: 135], although in my experience the former is more common than the latter (in minus cyl).

Comment by OD — August 15, 2012

Regarding the term of AXIS and MERIDIAN, pls let me quote from http://www.laramyk.com/resources/education/lens-form-and-theory/lens-form-sphere-cylinder-and-axis/

” Note how the power in the meridian of the cylinder axis is plano, while the power of the meridian perpendicular to the cylinder axis is +4.00 D”

Comment by Abraham A. Sutjiono — August 31, 2012

Why don’t you just say “with the rule astig” is the curvature of the vertical meridian is steeper than that of the horizontal meridian? I don’t understand what you mean by “positive cynlinders at 90 degree”

Comment by Jenny — January 8, 2013

Lets Simplify –

4 ‘W’s –
With,Wertical,Weaklings and Woneighty –

“With” the Rule Astigmatism is

“‘W’ertical” Meridian of Cornea is Steepest, commoner in

“Weaklings”(Children) whose cornea is similar to Rugby ball lying flat on ground because they cant hold it straight)

Glass prescription –

Minus Cylinder at 180 degree.(which would be effective at 90 degree axis and correct for steeper vertical meridian


0.00 Diopter Sphere
– 2.00 Diopter Cylinder at
180 degrees.

Comment by Dr Akash Patel — January 24, 2013

Now I’m gettin confused. if in “With The Rule” astigmatism the vertical meridian is steepest, this means the -Cyl should be on axis 90 or +Cyl on 180. Right?

Comment by Optometry Student 2 — March 14, 2013

The best so far:

“4 ‘W’s –
With,Wertical,Weaklings and Woneighty –”

Remember the terminology of “at” and “axis” which are always 90 degrees apart. This is a problem I’ve had with ODs, OMDs, and techs alike especially with keratometry.

The continual, antiquated usage of these terms (WTR/ATR) is basically unexcusable, a vestigal for progressive optometry except when studying for NBEO and the unnecessary and financially lucrative ABO certification.

Comment by HfredZ — April 17, 2013

WTR: the eye has more power VERTICALLY than horizontally. Think rugby ball/gridiron football with the steepest curve vertically. Corrected with -ve cylinder axis 180. In kids. Actually causes more defocus than ATR (lose more letters on eye chart). Can be + or minus 10 from 180. Defocuses horizonatal components of letters

ATR: the eye has more power HORIZONTALLY. Corrceted with -ve cyl axis 90. Causes least amount of letters lost on eye chart. Can be + or – 10 degres off axis

Oblique: betweeen WTR and ATR

Comment by Agent Smith — June 7, 2013

If automated keratometry reading of an eye is 43D@90degree and 44D@180degree, is it with the rule astigmatism?

Comment by Shoaib — June 13, 2013

@ Shpaib: Its against the rule.

Why? Look at my previous post: the power of the eye in the horizontal meridian is 44 D, but only 43 D in the vertical ie power H > power V, therefore ATR.

Comment by Agent Smith — June 17, 2013

@ Agent Smith I agree with you

Comment by Kimberly — July 10, 2013

Okay folks, very little of all of that is understandable to me, a lay person. But I have a problem. The eye doctor told me (an old person with cataracts) that my astigmatism was unusual in that it was vertical.
The eye surgeon operated on the right eye, implanting a distance vision lens and did a kertomony on the right eye. The right eye, after surgery, was 20/70 the first day, 20/50 on day 7, and 20/40 4 weeks later. The doctor said that it reduced my astigmatism by 50%. However, he said that my astigmatism was horizontal and the incisions he made were at the outside edge of the horizontal plane of the eye. I feel my astigmatism is hardly improved at all. He had said that I could use “over the counter” reading glasses; however, none of the drugstore strength of 325 is able to allow me to read very fine print that I can presently read with my left eye. Because the right eye is not where I had hoped, I’ve determined, at this point, that I need the left eye to have a distance lens so that between the two eyes, with glasses, I can see 20/20 for driving.
Did the doctor slice my cornea in the correct places?? I really would appreciate your answers. I’m scheduled to have the left cataract removed next Monday, and I still don’t understand whether the doctor did the right thing. Please help!

Comment by Virginia — July 28, 2013

Vertically cornea curve greater then horizontal.

Horizontally cornea curve greater then vertically.

Comment by sajjad hussain — September 11, 2013

Please explain astigmatism correction by cylinder with examle

Comment by arun — October 3, 2013

Vertically cornea curve greater then horizontal.
In with-the-rule astigmatism, a minus cylinder is placed in the horizontal axis to correct the refractive error (or a plus cylinder in the vertical axis).

Horizontally cornea curve greater then vertically.
In against-the-rule astigmatism, a plus cylinder is added in the horizontal axis (or a minus cylinder in the vertical axis).

Comment by Sajjad Hussain — October 26, 2013

Vertically cornea curve greater then horizontal.
In with-the-rule astigmatism, a minus cylinder is placed in the horizontal axis to correct the refractive error (or a plus cylinder in the vertical axis).

Horizontally cornea curve greater then vertically.
In against-the-rule astigmatism, a plus cylinder is added in the horizontal axis (or a minus cylinder in the vertical axis)

Comment by Sajjad Hussain — October 26, 2013

WTR- cornea is steeper vertically.
This means a -CYL NEEDED AT MERIDIAN 90.


Because the axis in this format corresponds to meridian of the sphere.

Comment by M.Asghar — March 12, 2014

43.60@73 and 44.23 @163. Is this WTR or ATR?

Comment by Fadil Noble — June 20, 2014

Hello,its nice paragraph on the topic of media print, we
all understand media is a great source of data.

Comment by tandblekning — December 6, 2014

WRL- minus cylinder lenses in horizontal meridian ie 180 degrees; in young eyes
ARL- minus cylinder lenses in vertical meridian ie 90 degrees.in older eyes

Comment by DrArijitKrNeogy — January 10, 2015

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