Principles of Atoric Lens Design
Principles of Atoric Lens Design
Principles of Atoric Lens Design
Lens Talk
Vol. 27, No. 03 (Jan. 1998)
spectacle lensesoften in conjunction with
higher-index materials.
BACKGROUND
Industry studies have shown that approximately
70% of all spectacle wearers receive a cylinder
correction for astigmatism. Further, 50% of these
wearers have corrections with over 0.50 D of
cylinder power. This article will show that
conventional lens design does not adequately
address the peripheral optical performance of
lenses with cylinder power. Moreover, it will
explain how new atoric lens designs can provide
superior optical performance for all patients
including those with astigmatism.
IN REVIEW
Spherical
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SYMMETRY AXIS
Aspherical
Sphere
Meridian
Curve
Cylinder
Meridian
Curve
+2.00 D
+2.00 D
+2.00 D
+2.00 D
Aspheric
Sphere
Curve
+2.00 D
+2.00 D
+2.00 sph
Figure 3. This +2.00 D spherical-powered lens has the
same power through every raidal direction (or meridian) of
the lens.
+2.00 D
+1.50 D
+1.50 D
Aspheric
Cylinder
Curve
+1.00 D
+1.00 D
+1.50 D
+1.50 D
+2.00 D
0.0
0.0
0.0
0.0
0.0
0.0
Spherical Surface
-4.0
-4.0
-4.0
-4.0
-4.0
-4.0
-4.0
-4.0
Aspheric Surface
-4.0
-2.5
-2.5
-1.5
-1.5
-2.5
-2.5
-4.0
Atoric Surface
Figure 6. Relative asphericity (or correction factors) for
spherical, aspheric, and atoric surfaces.
Aspheric Poly
Atoric Poly
Rx:
+4.00 2.00
Rx:
-6.00 2.00
Figure 7. Comparison of the fields of perfectly clear vision for best form, aspheric, and atoric polycarbonate lens designs. Two
prescriptions are shown. Note that the atoric lens design consistently provides a larger area of clear vision.
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