Transcript Modulation Transfer Function Measurement of the Alcon SN6AD3 Aspheric Apodized Diffractive Multifocal IOL

Modulation Transfer Function
Measurement of the Alcon SN6AD3
Aspheric Apodized Diffractive
Multifocal IOL
Jim Schwiegerling, PhD
Junoh Choi, MS
University of Arizona
Ophthalmology & Vision Sciences
Optical Sciences
Tucson, Arizona, USA
Financial Disclosure: The author receives research and travel support from
Alcon Research
Introduction
• An eye model in which IOLs are mounted in a saline-filled wet cell
behind the artificial cornea with clinical levels of spherical and
chromatic aberrations has been developed.
• Benchtop testing includes MTF measurement through line spread
function analysis, as well as imaging targets such as letter charts
and oblique pinhole sources.
• Digital SLR with macro lens attachment is used to create a
portable system to capture night scenes through the eye model.
• Alcon ReSTOR Aspheric, AMO ReZoom and Tecnis multifocal,
and Acri.Tec Acri.LISA lenses tested.
Line Spread Testing
Slit
Target
Badal
Lens
Iris
IOL in
Wet Cell
Illumination
CCD
Camera
Model
Cornea
Color
Filter
Wheel
Fourier Transform of the Line Spread gives the MTF of the lens
Through Focus MTF Comparison
3 mm Pupil; 50 cyc/mm
0.6
0.5
Modulation
0.4
ReSTOR
0.3
ReSTOR Aspheric
0.2
0.1
0
-6
-5
-4
-3
-2
-1
Object Vergence (Diopters)
0
1
2
Aspheric terms mainly
affect the lens periphery so
the performance of the two
lenses is nearly identical
for a 3 mm
pupil.
Through Focus MTF Comparison
6 mm Pupil; 50 cyc/mm
0.6
0.5
Modulation
0.4
ReSTOR
0.3
ReSTOR Aspheric
0.2
0.1
0
-6
-5
-4
-3
-2
-1
Object Vergence (Diopters)
0
1
2
For larger pupils, both
lenses bias distance vision.
The effect of the aspheric
term is to boost contrast in
the distance. Near vision
contrast is slightly improved
as well.
Target Imaging
Letter Chart Target
Targets can be used in place of
a slit on our setup. ETDRS
Letter chart shown for four
different types of multifocal
IOLs. Pupil size is 6.0 mm in
all cases.
Note the diminishing degree of
halo, especially with the
ReSTOR Aspheric.
Oblique Point Source
50 mm diameter pinhole target located 18° off the optical axis. Positive
and negative images are shown for four multifocal IOL styles. Note the
stray light flares for ReZoom, Tecnis MF and Acri.LISA
Portable Digital Imaging System
•Nikon Digital SLR camera
•Macro Lens
•Custom Eye model attachment
consisting of artificial cornea and wet
cell for mounting IOLs
The system mimics the vergence and
imaging properties of the human eye.
Night Scene
ReSTOR
Aspheric
Tecnis
ZM900
ReZoom
Acri.Lisa
Multifocal
Night Scene
ReSTOR
Aspheric
Tecnis
ZM900
ReZoom
Acri.Lisa
Multifocal
Discussion
• MTF Testing showed that the aspheric ReSTOR gives an increase
in contrast for distant objects for large pupil sizes.
• The diffractive elements tend to cause arcs around bright light
sources in nighttime scenes, whereas the zonal refractive causes a
continuous flare. Apodization suppresses many of these artifacts.
• There are less stray light effects in Alcon’s aspheric apodized
diffractive than with the other multifocal IOLs.