1. Comparative Global Literature Review of Visual and Optical Quality of Refractive, Diffractive, and Hybrid IOL Designs
James P. McCulley, MD Department of Ophthalmology University of Texas Southwestern Medical Center at Dallas
Dr. McCulley is a consultant for
Alcon Laboratories, Inc.

2. 23 unique journal articles
Purpose & Methods
PURPOSE: To investigate whether trends in superiority exist for optical characteristics and patient outcomes when making pairwise comparisons between 2 of the following 3 IOL types: refractive, diffractive, and hybrid of refractive with apodized diffractive.
METHODS: Literature searches for published articles
OvidSP Database (MEDLINE, EMBASE pooled), JRS, and JCRS
Keyword search #1: refractive AND diffractive AND (multifocal OR bifocal) AND intraocular lens
Keyword search #2: compar* AND (multifocal OR bifocal) NOT monofocal AND intraocular lens
Keep only the applicable comparative studies
23 unique journal articles
*Wildcard asterisk returns “comparative,” “compared,” “comparison,” etc.
All results restricted to English language

3. Methods: Pooled Source Data
23 studies (5 bench, 18 human); total 1411 eyes
(Full-Optic) Diffractive IOLs
Refractive IOLs
Hybrid IOLs (Refractive Outer Ring, Apodized Diffractive Center Disk)
Model
Studies, n
Tecnis®, AMO 11
Array®, AMO 12
ReSTOR®, Alcon
17*
CeeOnTM, Pfizer 6
ReZoom®, AMO 10
A-TwinTM, Acri.Tec 3
A-LISATM, Acri.Tec 2
825x +4, 3M 1
Study designs
Bilateral groups: 9 studies
Contralateral: 1 study
By eye: 8 studies
Bench: 5 studies
Older IOL names or manufacturers updated to most recent. *16 Spherical SN60D3 or SA60D3, 1 Aspheric SN6AD3, 0 Aspheric SN6AD1

4. Lens Characteristics Tecnis® A-LISATM ReZoom® ReSTOR®
Diffractive IOLs Refractive IOLs Hybrid IOLs
Tecnis®
A-LISATM
ReZoom®
ReSTOR®
Lens Type
Multi- Piece
Single- Piece
Multi- piece
Single- or Multi-Piece
Lens Material
Polysiloxane or acrylic
Foldable acrylate with 25% water content, hydrophobic surface, and UV-absorber
Hydrophobic acrylic optic, poly-methyl methacrylate (PMMA) haptics
UV-absorbing & blue light filtering acrylate/ methacrylate copolymer

5. Results: Optical Bench Test Outcomes
5 Studies; 5 result types; 18 pairwise superiorities
Outcomes included defocus transfer function, night driving photograph, modulation transfer function (near, distance, various pupil sizes), Strehl ratio, USAF target resolution
Top three superiorities (others only 1 superiority)
Hybrid IOLs superior over refractive IOLs, n=6
Diffractive IOLs superior over refractive IOLs, n=5
Hybrid IOLs superior over diffractive IOLs, n=4
Diffractive vs…
Refractive vs…
Hybrid vs…
Winners
Results were not tabulated unless a superiority was observed (ie, equivalences and similarities not counted)

6. Results: Near Visual Acuity (≤40 cm)
14 of 18 studies found pairwise near VA superiorities
Includes UCVA, BCVA, photopic (± glare), mesopic (± glare), defocus curve data, monocular/binocular, various contrast levels
Top three superiorities:
Diffractive IOLs superior over refractive IOLs, n=26
Hybrid IOLs superior over refractive IOLs, n=8
Hybrid IOLs superior over diffractive IOLs, n=5
Diffractive vs…
Refractive vs…
Hybrid vs…
Winners
Results were not tabulated unless a superiority was observed (ie, equivalences and similarities not counted)

7. Results: Intermediate Visual Acuity (>40 cm to 3 m)
10 of 18 studies found pairwise intermediate VA superiorities
Includes UCVA, BCVA, photopic (± glare), mesopic (± glare), defocus curve data, monocular/binocular, various contrast levels
Trends in superiority were not consistent:
In refractive vs diffractive IOLs: 7 for refractive, 5 for diffractive
In diffractive vs hybrid IOLs: 5 for diffractive, 1 for hybrid
In refractive vs hybrid IOLs: 5 for refractive, 0 for hybrid
All hybrid studies were for +4.0 D IOLs, not +3.0 D IOLs
Diffractive vs…
Refractive vs…
Hybrid vs…
Winners
Results were not tabulated unless a superiority was observed (ie, equivalences and similarities not counted)

8. Intermediate Visual Acuity: SN6AD1 versus SN6AD3 IOLs
The new +3.0 D IOL (SN6AD1) uses the existing +4.0 D IOL (SN6AD3) platform
Vergence, D
40 cm
33 cm
50 cm
Visual acuity, logMAR
Intermediate visual acuity is improved with +3.0 D IOL
Near focus is farther out from the eye with +3.0 D IOL
Maxwell et al. J Cataract Refract Surg. 2009: 35;

9. Results: Far Distance Visual Acuity (>3 m)
4 of 18 studies found pairwise far VA superiorities
Includes UCVA, BCVA, photopic ( photopic + glare, mesopic, mesopic + glare, defocus curve data, monocular/binocular, various contrast levels
Top three superiorities:
Hybrid IOLs superior over diffractive IOLs, n=8
Tie for second place: refractive vs diffractive, 2 superiorities each
Diffractive vs…
Refractive vs…
Hybrid vs…
Winners
Results were not tabulated unless a superiority was observed (ie, equivalences and similarities not counted)

10. Underpowered/Unclear Comparisons
Visual disturbances: superiorities found by 2 of 7 studies
Diffractive > Refractive, negative dysphotopsia (n=1) and halo (n=1)
Contrast sensitivity: superiorities found by 7 of 9 studies
Various spatial frequencies and lighting conditions
Diffractive>Refractive, n=3
Hybrid>Refractive, n=3
Refractive>Diffractive, n=4
Refractive>Hybrid, n=3
Higher-order aberrations: superiorities found by 3 of 4 studies
Included coma, spherical aberration, various pupil sizes
Hybrid>Refractive, n=12 results
Diffractive>Hybrid, n=8 results
Reading acuity and speed: superiorities found by 3 of 3 studies
Various lighting conditions, distances, correction
Top acuity superiority: Diffractive > Refractive (n =15 results)
Top speed superiority: Diffractive > Refractive (n=9 results)

11. Summary
Based on the number of results from articles comparing one type of multifocal IOL to another, the following possible trends were observed:
For published optical quality results,
Hybrid > Refractive
Diffractive > Refractive
For published visual acuity results,
Near vision
Hybrid > Diffractive
Intermediate vision
Refractive vs diffractive: differences not clear
Refractive and diffractive superior to hybrid (+4.0 D model), but SN6AD1 (+3.0 D model) improves intermediate visual acuity
Distance vision
Tie for second place: Refractive vs Diffractive
Superiority results were less clear for visual disturbances, contrast sensitivity, higher-order aberrations, reading acuity, reading speed

12. References (Database for Literature Review)
Alfonso et al. J Cataract Refract Surg 2008;34:
Alio et al. J Cataract Refract Surg 2004;30:
Artigas et al. J Cataract Refract Surg 2007;33:
Chang. J Cataract Refract Surg 2008;34:
Chiam et al. J Cataract Refract Surg 2007;33:
Choi et al. J Refract Surg 2008;24:
Gunenc et al. J Refract Surg 2008;24:
Hutz et al. J Cataract Refract Surg 2006;32:
Hutz et al. J Refract Surg 2008;24:
Maxwell et al. J Cataract Refract Surg 2009;35:
Mester et al. J Cataract Refract Surg 2007;33:
Ortiz et al. J Cataract Refract Surg 2008;34:
Palmer et al. J Refract Surg 2008;24:
Pepose et al. Am J Ophthalmol 2007;144:
Pieh et al. Arch Ophthalmol 2002;120:23-28.
Renieri et al. Eur J Ophthalmol 2007;17:
Richter-Mueksch et al. J Cataract Refract Surg 2002;28:
Schmidinger et al. J Cataract Refract Surg 2006;32:
Schwiegerling. J Refract Surg 2007;23:
Toto et al. J Cataract Refract Surg 2007;33:
Walkow et al. Ophthalmology 1997;104:
Weghaupt et al. J Cataract Refract Surg 1998;24:
Zelichowska et al. J Cataract Refract Surg 2008;34: