1. Comparison of MTF Performance of Spherical and Toric Apodized Diffractive Multiofocal IOLs
Warren Hill, MD, FACS
East Valley Ophthalmology
5620 E. Broadway Road
Mesa, AZ
Jim Schwiegerling, PhD
University of Arizona
Optical Sciences
Ophthalmology & Vision Sciences
Disclosure:
Hill: Consultant, Speaker & Research Support Alcon Research
Schwiegerling: Research & Travel support from Alcon Research.

2. Introduction
The optical performance of +3D-Add aspheric apodized diffractive multifocal IOLs is compared to an equivalent toric +3D-Add aspheric apodized diffractive multifocal IOL.
Spherical Lens is ReSTOR SN6AD1 (Alcon Laboratories)
Toric Lens is ReSTOR SND1T5 (Alcon Laboratories)
The toric lens is measured along its astigmatic axis as well as perpendicular to the astigmatic axis

3. Measuring MTF
The IOL is placed in a wet cell mounted behind an artificial cornea.
The blurred image of a slit target is analyzed to determine the Modulation Transfer Function (MTF).
The slit is moved axially to measure MTF for different object distances.

4. Toric Multifocal
Since the lens under test is toric, its imaging properties change with meridian. MTF testing for the toric lens was performed along the 45° and 135° meridians. For the spherical lens, performance is tested along a vertical meridian.
45°
135°

5. Slit Images
The slit images are for different object vergences measured from spectacle plane.
The contrast of the slit images has been reversed to highlight the structure.
The left column is along the toric axis, while the right column is 90° away.
The left column shows foci for distance (0D) and +2D, which shows the multifocal effect (equivalent to +3D add in IOL plane).
The right column shows foci for +2D and +4D, which shows the combined effect of the multifocal powers and the toric power.

6. Slit Images Distance Foci Near Foci Spherical Lens Toric Lens @45°

7. MTF
Spatial Frequency = 50 cyc/mm and a 6 mm pupil.

8. MTF Registered
Spatial Frequency = 50 cyc/mm and a 6 mm pupil.

9. Conclusion
The MTFs of the toric multifocal lens designs along the principal toric axes are comparable.
The toric lenses give similar results to their equivalent spherical powered counterparts.
Based on these results, the new toric apodized multifocal IOL should deliver the same optical quality as the currently available SN6AD1 (Alcon Laboratories), since the only difference between the lenses is the toric component.
The key limiting factor to performance of these lenses will be matching the toric power to the corneal astigmatism and alignment of the IOL axis with the corneal astigmatic axis