1. Comparison of visual function following piggyback implantation of Acrysof ReSTOR intraocular lenses with Tecnis multifocal ZM900 intraocular lenses. Rodrigo Vaz, MD Leonardo Akaishi, MD Patrick F. Tzelikis, MD None of the authors has a financial or proprietary interest in any material or method mentioned.

2. Purpose To compare the postoperative outcome of piggyback implantation using the AcrySof ReStor lens with Tecnis ZM900 multifocal intraocular lenses (IOL).

3. Material / Methods This prospective comparative study included patients with age-related cataract, primary hyperopia or hyperopic astigmatism, a normal ophthalmologic examination besides senile cataract, and unsatisfactory correction with glasses. Information collected included uncorrected visual acuity (UCVA) for near and distance, best corrected visual acuity (BCVA), and spherical equivalent (SE) before and after the surgery. All patients were followed for 6 months

4. The three lenses used in this study were TECNIS® ZM900 multifocal IOL, AcrySof ReStor® and CLARIFLEX®. The multifocal IOL (Tecnis ZM900 or AcrySof ReStor) was first implanted in the capsular bag and the Clariflex® lens was implanted second in the ciliary sulcus. Material / Methods

5. The TECNIS® multifocal IOL (Model ZM900, AMO, Santa Ana, CA) is a 3-piece diffractive multifocal lens with 6.00 mm polysiloxane optic. The AcrySof ® ReSTOR ® (Model SA60D3, Alcon Surgical Laboratories, Dallas, Texas) is an acrylic foldable single- piece IOL. The CLARIFLEX® (Model AMO, Advanced Medical Optics, Santa Ana, California) is 3-piece monofocal lens with 6.00 mm biconvex square-edged silicone optic and 10-degree angulated C polymethyl-methacrylate (PMMA) haptics. Material / Methods

6. The Holladay formula was used to calculate the IOL power when there was a short axial length (< 22.0 mm) and the SRK/T formula was used when there was an average axial length (≥ 22.0 mm). The A- constant used was 119.8 for the TECNIS multifocal IOL, 118.6 for the AcrySof ReStor and 118.4 for the CLARIFLEX IOL. Axial length was measured with the IOL Master (Carl Zeiss Meditec AG), and the targeted postoperative refractive error was 0.0 Material / Methods

7. Preoperative Tecnis ZM900 (n=20 eyes) ReStor (n=21 eyes) P value Axial length 20.80 mm (SD:±0.80)21.68 mm (SD:±0.39) P<0,001 Power IOL (D) 26.75 D (SD: ±1.95)22.0 D (SD: ±1.75)P<0.001 UCVA0.08 (20/250) (SD: ±0.11) 0.25 (20/80) (SD: ±0.06) P<0.001 BCVA0.67 (20/30) (SD: ±0.08) 0.9 (20/22) (SD: ±0.17) P=0.02 SE+ 6.25 D (SD: ± 2.25) + 4.25 D (SD: ±1.55)P=0.002 Teste t Student (SPSS) Results

8. Postoperative (6 months) Tecnis ZM900 (n=20 eyes) ReStor (n=21 eyes) P value UCVA for distance 0.67 (20/30) (SD: ± 0.15) 0.86 (20/23) (SD: ± 0.16) P=0.002 UCVA for near 33 cm J1 P=0.14 BCVA for distance 0.90 (20/22) (SD: ± 0.10) 1.00 (20/20) (SD: ± 0.05) P=0.002 BCVA at 60 cm J4.5J5P=0.08 SE0.00 D (SD: ± 0.45) -0.25 D (SD: ± 0.40) P=0.06 Teste t Student (SPSS) Results

10. After a follow-up of 6 months, halos were reported as severe by 8.3%, moderate by 33.3% and absent or mild by 58.4% of patients in the Tecnis group. In the ReStor group halos were reported as severe by 9.0%, moderate by 27.3% and absent or mild by 63.7%. No interlenticular opacification (ILO) or another postoperative complication related to piggyback lenses was observed in our series. Results

11. Conclusion Overall, the use of a multifocal IOL in a piggyback fashion appears to be a safe and efficient procedure and a good refractive solution. Implanting 2 piggyback IOLs was beneficial in eyes with short axial length. The AcrySof ReSTOR IOL gave better outcomes than the Tecnis multifocal IOL in UCVA and BCVA for distance, probably because in the Tecnis group the eyes had shorter axial length and required higher diopter lenses.