1. Hayashi Eye Hospital, Fukuoka, Japan
Effect of astigmatism on visual acuity in eyes with a diffractive multifocal intraocular lens
Ken Hayashi, MD
Motoaki Yoshida, MD
Shin-ichi Manabe, MD
Hideyuki Hayashi, MD
Hayashi Eye Hospital, Fukuoka, Japan
The authors have no financial interest in any of the materials mentioned in this paper.

2. Purpose
Our previous study showed that postoperative refractive astigmatism significantly affects the visual function in eyes with a refractive-type multifocal intraocular lens (IOL). The purpose of this study was to examine the effect of refractive astigmatism on visual acuity from far to near distance in eyes with a diffractive-type multifocal IOL.

3. Patients 96 patients scheduled for bilateral cataract surgery
1) Diffractive multifocal IOL with +4.0 D add power
(Alcon ReSTOR 4D; SN6AD3) patients
2) Diffractive multifocal IOL with +3.0 D add power
(Alcon ReSTOR 3D; SN6AD1) patients
3) Monofocal IOL with the same material and design
(Alcon SN60WF) patients
Not randomized because of ethical reasons
Only the first-operated eye
Exclusion criteria: 1) severe pathology of the optic nerve, macula, and cornea, 2) corneal astigmatism ≥ 1.5D, 3) history of ocular surgery, and 4) irregular-shape pupil

4. Methods Simulation of astigmatism
1) Various diopters (0D, 0.5D, 1.0D, 1.5D, and 2.0D) of cylindrical lens were added at the 90° meridian
2) Only an against-the-rule astigmatism
Examination
1) Distance-corrected visual acuity (VA) from far to near (KOWA AS-15)
2) Manifest spherical equivalent value
3) Keratometric cylinder
4) Pupillary diameter‥ Colvard pupillometer
*Examined at approximately 3 months after surgery

5. Change in all-distance visual acuity by diopters of added astigmatism in the ReSTOR+4D group

6. Change in all-distance visual acuity by diopters of added astigmatism in the monofocal IOL group

7. Comparison of all-distance visual acuity in the three IOL groups

8. Comparison of all-distance visual acuity in the three IOL groups

9. Comparison of all-distance visual acuity in the three IOL groups

10. Comparison of all-distance visual acuity in the three IOL groups

11. Eyes achieving a visual acuity of 20/40 at both far and near by IOL group
30 (100%)
26 (26.7%)
12 (40.0%)
1 (3.3%)
26 (86.7%)
20 (66.7%)
6 (20.0%)
2 (6.7%)
3 (10.0%)
5 (16.7%)
< .0001*
.0812
.5853
ReSTOR 4D ReSTOR 3D Monofocal P value
*Number of eyes in monofocal IOL group were
significantly less than in both multifocal IOL groups

12. Conclusions
1) When postoperative astigmatism is approximately within 1.0D, the diffractive multifocal IOL provided useful far and near VA.
2) With astigmatism of 1.0D or less, near VA or intermediate VA with the diffractive multifocal IOLs was better than that did with the monofocal IOL.
3) Eyes with astigmatism of approximately 1.0D or less are definitely candidates for implantation of a diffractive multifocal IOL.