Difference between revisions of Astigmatism

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The link between astigmatism strength and visual acuity is weak. How your eyes and [[visual cortex]] respond to astigmatism is a greater factor in visual acuity than the number of dipoters.<ref>{{Cite journal |last=Remón |first=Laura |last2=Tornel |first2=Marta |last3=Furlan |first3=Walter D. |date=2006-05 |title=Visual Acuity in Simple Myopic Astigmatism: Influence of Cylinder Axis |url=https://journals.lww.com/optvissci/Abstract/2006/05000/Visual_Acuity_in_Simple_Myopic_Astigmatism_.11.aspx |journal=Optometry and Vision Science |language=en-US |volume=83 |issue=5 |pages=311–315 |doi=10.1097/01.opx.0000216099.29968.36 |issn=1538-9235}}</ref> If the standard advice for correcting astigmatism does not work for you, you may need a more gradual reduction.

Regardless of how the myope reduces their lenses, the goal of each reduction is to have a small amount of "useful blur", to be cleared up with [[active focus]] and good habits.

==Spherical equivalent==

The '''spherical equivalent''' of cylinder lenses may be useful, to simplify the reduced lens path. 0.50 cylinder means the power varies from 0D on one axis to 0.5D on the perpendicular axis. This can be substituted by the spherical power with the averaged value of 0.25D. For example, a full prescription of "-1.00 Sphere -1.50 Cylinder" could be converted to "-1.75 Sphere". The resulting spherical equivalent is not intended to compensate for the asymmetry of the lens, so it will introduce some directional blur.

~~Regardless of how the myope reduces their lenses, the goal of each reduction is to have a small amount of "useful blur", to be cleared up with [[active focus]] and good habits.~~

===Axis===

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 The link between astigmatism strength and visual acuity is weak.  How your eyes and [[visual cortex]] respond to astigmatism is a greater factor in visual acuity than the number of dipoters.<ref>{{Cite journal |last=Remón |first=Laura |last2=Tornel |first2=Marta |last3=Furlan |first3=Walter D. |date=2006-05 |title=Visual Acuity in Simple Myopic Astigmatism: Influence of Cylinder Axis |url=https://journals.lww.com/optvissci/Abstract/2006/05000/Visual_Acuity_in_Simple_Myopic_Astigmatism_.11.aspx |journal=Optometry and Vision Science |language=en-US |volume=83 |issue=5 |pages=311–315 |doi=10.1097/01.opx.0000216099.29968.36 |issn=1538-9235}}</ref>  If the standard advice for correcting astigmatism does not work for you, you may need a more gradual reduction.
+Regardless of how the myope reduces their lenses, the goal of each reduction is to have a small amount of "useful blur", to be cleared up with [[active focus]] and good habits.
+==Spherical equivalent==
 The '''spherical equivalent''' of cylinder lenses may be useful, to simplify the reduced lens path. 0.50 cylinder means the power varies from 0D on one axis to 0.5D on the perpendicular axis. This can be substituted by the spherical power with the averaged value of 0.25D. For example, a full prescription of "-1.00 Sphere -1.50 Cylinder" could be converted to "-1.75 Sphere". The resulting spherical equivalent is not intended to compensate for the asymmetry of the lens, so it will introduce some directional blur.
-Regardless of how the myope reduces their lenses, the goal of each reduction is to have a small amount of "useful blur", to be cleared up with [[active focus]] and good habits.
 ===Axis===
 {{Main|Axis}}