The document discusses aspheric optics and how aspheric surfaces can help control spherical aberration. It explains that aspheric means the radius of curvature changes from the center to the periphery of the lens rather than being perfectly spherical. Aspheric surfaces can help control aberrations produced by corrective lenses or the inherent aberrations of the eye. Spherical aberration, one of the most common higher-order aberrations, causes blurring and halos that are more prominent in low light or with dilated pupils. Aspheric surfaces can counterbalance the average positive spherical aberration of the population to improve image quality and reduce halos.

1. ASPERIC OPTICS
SIMPLIFIED…
Nilesh Thite M. Optom, FIACLE
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2. Aspheric Optics
Simplified
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3. Progress
Is it progress if cannibal uses knife and
fork?
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4. Aspheric Surface
Aspheric means non- spherical
The radius of curvature, hence
curvature changes from centre to
periphery
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6. Conics
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7. Asphericity for Different Reasons
 Progressive Addition
 Control of aberration produced by the
corrective lenses
 Control of aberration of the Eye
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8. Perfection..
Perfection has one grave defect.. It is apt
to be dull
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9. Aberration
Deviation from proper or expected course
Inability of an optical system to bring all
incident rays to a desired image point
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10. Spherical Aberration
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11. Spherical Aberration
One of the most frequent types of higher order
Aberrations seen in population
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12. Spherical Aberration
Perceived as blurring or halos
Prominent in low illumination or low contrast
Dilated pupils
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13. Aberration and Vision
Mean Spherical Aberration
-0.10
-0.05
0.00
0.05
0.10
0.15
0.20
0.25
4.0 4.5 5.0 5.5 6.0 6.5
Pupil aperture / mm
Z400
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15. Counterbalancing Inherent
Aberration
SF>1
SF<1
Spherical
aberration
Power
-6.00D -5.00D-4.00D-3.00D-2.00D-1.00D
-0.10μm
-0.20μm
LEVEL OF SPHERICAL ABERRATION OF CONTACT
LENS WITH SPHERICAL SURFACES
LEVEL OF SPHERICAL ABERRATION TO THEORETICALLY
OFFSET POPULATION AVERAGE
(ASSUMING PERFECT LENS CENTRATION)
+0.20μm
+0.10μm
0
LEVEL OF POPULATION AVERAGE POSITIVE
SPHERICAL ABERRATION
-7.00D
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17. Spherical Aberration No Spherical Aberration
Spherical Aberration Induces Haloes and
Reduces Contrast and Ultimately Resolution
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18. Impact of Aberrations
Simulated retinal image at 6mm pupil size
with +0.15 microns of spherical aberration
Low light image
without spherical
aberration
Low light image with
spherical aberration
Simulated retinal image – non aberrated
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19. Know your lens before committing benefits
to the patients
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20. Landline, Mobiles and communicators
We are Evolving..
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