ophthalmology & vision sciences
DESCRIPTION
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.TRANSCRIPT
Modulation Transfer Function Measurement of the Alcon SN6AD3
Aspheric Apodized Diffractive Multifocal IOL
Jim Schwiegerling, PhDJunoh Choi, MS
University of ArizonaOphthalmology & Vision Sciences
Optical SciencesTucson, Arizona, USA
Financial Disclosure: The author receives research and travel support fromAlcon 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
CCDCamera
Color Filter Wheel
ModelCornea
Badal Lens
SlitTarget
Illumination
Iris
IOL inWet Cell
CCDCamera
Color Filter Wheel
ModelCornea
Badal Lens
SlitTarget
Illumination
Iris
IOL inWet Cell
Fourier Transform of the Line Spread gives the MTF of the lens
Through Focus MTF Comparison 3 mm Pupil; 50 cyc/mm
0
0.1
0.2
0.3
0.4
0.5
0.6
-6 -5 -4 -3 -2 -1 0 1 2
Object Vergence (Diopters)
Mod
ulat
ion
ReSTOR
ReSTOR Aspheric
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
0.1
0.2
0.3
0.4
0.5
0.6
-6 -5 -4 -3 -2 -1 0 1 2
Object Vergence (Diopters)
Mod
ulat
ion
ReSTOR
ReSTOR Aspheric
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 TargetTargets 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 m 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 SceneReSTORAspheric
ReZoom
Tecnis ZM900
Acri.LisaMultifocal
Night SceneReSTORAspheric
ReZoom
Tecnis ZM900
Acri.LisaMultifocal
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.