Visual performance after bilateral implantation of 2 new presbyopia-correcting intraocular lenses: Trifocal versus extended range of vision

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ARTICLE

Visual performance after bilateral implantation of 2 new presbyopia-correcting intraocular lenses: Trifocal versus extended range of vision Gaspare Monaco, MD, Mariangela Gari, MD, Fabio Di Censo, MD, Andrea Poscia, MD, Giada Ruggi, Antonio Scialdone, MD

Purpose: To compare the visual outcomes and quality of vision of 2 new diffractive multifocal intraocular lenses (IOLs) with those of a monofocal IOL. Setting: Fatebenefratelli e Oftalmico Hospital, Milan, Italy. Design: Prospective case series. Methods: Patients had bilateral cataract surgery with implantation of a trifocal IOL (Panoptix), an extended-range-of-vision IOL (Symfony), or a monofocal IOL (SN60WF). Postoperative examinations included assessing distance, intermediate, and near visual acuity; binocular defocus; intraocular and total aberrations; point-spread function (PSF); modulation transfer function (MTF); retinal straylight; and quality-of-vision (QoV) and spectacle-dependence questionnaires. Results: Seventy-six patients (152 eyes) were assessed for study eligibility. Twenty patients (40 eyes) in each arm of the study (60 patients, 120 eyes) completed the outcome assessment. At the

A

variety of different optical designs have been devised to provide correction of presbyopia after cataract surgery. At present, multifocal intraocular lenses (IOLs) with 2 or more optical foci or even a continuous focal range are considered the most effective and preferred pseudoaccommodative approach.1 One of the most commonly used optical patterns is used for diffractive multifocal IOLs. These patterns are based on the principle of light diffraction by microscopic steps across the optical surface of the IOL, creating 2 focal planes. Near vision is provided primarily by letting the patient perceive the retinal image of 1 focused plane with the other plane blurred.2

4-month follow-up, the trifocal group had significantly better near visual acuity than the extended-range-of-vision group (P Z .005). The defocus curve showed the trifocal IOL had better intermediate/near performance than the extended-range-of-vision IOL and both multifocal IOLs performed better than the monofocal IOL. Intragroup comparison of the total higher-order aberrations, PSF, MTF, and retinal straylight were not statistically different. The QoV questionnaire results showed no differences in dysphotopsia between the multifocal IOL groups; however, the results were significantly higher than in the monofocal IOL group.

Conclusions: Both multifocal IOLs seemed to be good options for patients with intermediate-vision requirements, whereas the trifocal IOL might be better for patients with near-vision requirements. The significant perception of visual side effects indicates that patients still must be counseled about these effects before a multifocal IOL is implanted. J Cataract Refract Surg 2017; 43:737–747 Q 2017 ASCRS and ESCRS

The major limitations of multifocal IOLs are loss of contrast sensitivity, unwanted or disturbing visual effects, and the inability to provide satisfactory vision at an intermediate distance.3 To reduce these drawbacks and improve the intermediate focal plane, manufacturers have introduced new models of diffractive multifocal IOLs that incorporate various technical approaches in their designs. This study assessed the visual outcomes and quality of vision for 2 diffractive multifocal IOLs and compared them with the results achieved with a monofocal IOL.

Submitted: September 1, 2016 | Final revision submitted: March 5, 2017 | Accepted: March 11, 2017 From the Ophthalmology Unit (Monaco, Di Censo, Ruggi, Scialdone), Fatebenefratelli e Oftalmico Hospital, ASST Fatebenefratelli Sacco, Milan, and the Ophthalmology Unit (Gari) and the Public Health Unit (Poscia), Catholic University of Sacred Heart, Rome, Italy. Presented at the XXXIV Congress of the European Society of Cataract and Refractive Surgeons, Copenhagen, Denmark, September 2016. Corresponding author: Gaspare Monaco, MD, Ophthalmology Unit, Fatebenefratelli e Oftalmico Hospital, ASST Fatebenefratelli Sacco, Piazza Principessa Clotilde, 320121, Milano, Italy. E-mail: [email protected]. Q 2017 ASCRS and ESCRS Published by Elsevier Inc.

0886-3350/$ - see frontmatter http://dx.doi.org/10.1016/j.jcrs.2017.03.037

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PATIENTS AND METHODS This prospective randomized double-blind controlled clinical study was performed at Fatebenefratelli e Oftalmico Hospital, Milan, Italy. Approval from the Medical Ethics Committee was obtained. The principles of Good Clinical Practice were adhered to in accordance with the Declaration of Helsinki. Patient Enrolment and Randomization The study included patients having sequential bilateral cataract surgery who were interested in presbyopia correction and willing to adhere to the study protocol. All patients had a full ophthalmologic examination, including refractive status, distance visual acuity, slitlamp evaluation, tonometry, fundoscopy, biometry, corneal topography and aberrometry; optical coherence tomography was performed in some cases. Inclusion criteria were lens opacity causing a reduction in visual quality and the motivation for spectacle independence. Exclusion criteria were professional night drivers, pilots, and those with other occupations for whom induced dysphotopsia could put their career at risk; inability to cooperate; difficulties comprehending written or spoken language; ocular comorbidity that might hamper postoperative visual acuity; previous refractive surgery; pseudoexfoliation and/or zonular fiber weakness; optical biometry impractical because of dense cataract; axial lengths of 22.00 mm or shorter or 26.00 mm or longer; a mean central corneal power of 41.00 diopters (D) or lower or 46.00 D or higher; corneal astigmatism of 0.75 D or higher; an irregular astigmatism index of 0.54 or higher; root mean square (RMS) of corneal higher-order aberrations (HOAs) of 0.30 mm or higher at a 4.0 mm pupil diameter; and angle k of 0.29 mm or higher. Eligible patients were identified at their preoperative assessments and provided with an explanation of the study and its aims. The patients were cautioned that achieving spectacle independence is challenging and that not every IOL available at present is suitable for every patient because of the complexity of lifestyle choices and the anatomy of the eye. The patients were provided with detailed study information designed to be readily comprehensible to a nonexpert reader. After 24 hours, the study coordinators telephoned the patients to provide further counseling and to obtain provisional consent to participate in the trial. Confirmation of willingness to participate in the study was obtained 4 to 7 days before surgery. Written consent to participate in the study was then obtained by participating surgeons on admission for first-eye surgery. After enrollment, patients were randomly allocated to bilateral implantation of a trifocal IOL, an extended-range-of-vision IOL, or a monofocal IOL. Randomization was performed using Minim,A a free minimization program that incorporates a single factor (ie, the surgeon). Intraocular Lenses The trifocal TFNT00 (Acrysof IQ Panoptix, Alcon Laboratories, Inc.) is an ultraviolet (UV) blue light–filtering foldable multifocal IOL. The IOL is hydrophobic acrylic and single piece with a 6.0 mm optic, 2 open-loop haptics, and an overall diameter of 13.0 mm. The optic diffractive structure is in the central 4.5 mm of the anterior surface and distributes the incoming light to create C2.17 D intermediate and C3.25 D near addition (add) powers. The anterior surface has negative spherical aberration (
0.1 mm). The diffractive design of the IOL is a widely used revision of the earlier Restor IOL (Alcon Laboratories, Inc.). The goal of the revision was to increase image quality, reduce side effects, and create 2 near foci.B The ZXR00 (Tecnis Symfony, Abbott Laboratories, Inc.) is a foldable, single-piece, hydrophobic, UV-filtering acrylic, openloop haptic multifocal IOL with an overall diameter of 13.0 mm and an optic diameter of 6.0 mm. The anterior surface of the optic is aspheric (
0.27 mm), and the posterior surface incorporates a Volume 43 Issue 6 June 2017

5.5 mm diffractive area designed to compensate for the eye’s chromatic aberrations and to increase depth of focus. The diffractive design, called echelette, is a proprietary pupil-independent type of diffraction grating that enhances contrast sensitivity using achromatic technology for the correction of chromatic aberration. According to the manufacturer, the IOL creates an elongated focus regardless of pupil size (ie, an extended range of vision) without defined focal planes throughout.C The monofocal SN60WF (Acrysof, Alcon Laboratories, Inc.) is a foldable, single-piece, open-loop haptic, hydrophobic acrylic, blue light–filtering IOL with an overall diameter of 13.0 mm and an optic diameter of 6.0 mm. It incorporates a posterior aspheric surface with negative spherical aberration of
0.19 mm.D Intraocular Lens Power and Surgical Technique The IOL dioptric power was selected to target emmetropia using the IOL power corresponding to the negative (myopic) predicted refractive outcome closest to zero. The IOL constants were configured using the manufacturers’ calculation constants provided for multifocal IOLs and optimized values provided for the monofocal IOL by the User Group for Laser Interference BiometryE and internal optimization. The SRK/T formula4 was calculated, and the power closest to the mean was chosen. One of 3 ophthalmic surgeons performed phacoemulsification and IOL implantation through a 2.2 mm limbal corneal incision. The IOLs were implanted in the capsular bag using the manufacturer’s recommended IOL loading and injection technique. The interval between the first-eye and second-eye surgery was 2 to 6 weeks. Patient Assessment and Outcome Measures All patients were examined preoperatively and postoperatively in accordance with routine institutional clinical care policies for patients having cataract surgery. A trained certified ophthalmic assistant (G.R.) and an ophthalmologist (M.G.) assessed primary and secondary outcomes 4 months after surgery in the second eye. The primary outcome measure was monocular distancecorrected near visual acuity (DCNVA). Secondary outcomes were monocular uncorrected (UDVA) and corrected (CDVA) distance visual acuities, uncorrected intermediate visual acuity and distance-corrected intermediate visual acuity (DCIVA), uncorrected near visual acuity (UNVA), DCNVA, binocular defocus test results, internal and total (ocular) aberrations, retinal straylight, quality-of-vision (QoV) and spectacle-dependence questionnaires, and accuracy of IOL power calculation. Distance vision was measured with logarithm of minimum angle of resolution (logMAR) notation at 100% contrast using the Early Treatment Diabetic Retinopathy Study (ETDRS) charts (ETDRS Standardized Viewer Model No. ESV3000) under photopic conditions (85 candelas [cd]/m2) at 3 m. Intermediate and near visual acuities were measured using the Sloan ETDRS Format Near Vision Chart 3 with 100% contrast under photopic conditions (85 cd/m2) at 67 cm (equivalent to C1.50 D add) for intermediate vision and 40 cm for near vision. During the defocus test, the patient was corrected for distance acuity in both eyes while viewing a distance eye chart. This, by definition, was the peak visual acuity for all lenses tested. Then, additional lenses were added in
0.50 D increments up to a
4.00 D sphere in front of both eyes simultaneously to produce defocus, after which acuity was tested. Quality of vision was assessed using a refractive power/corneal analyzer system (OPD-Scan II, Nidek Co., Ltd.) that converts dynamic skiascopy datapoints (up to 1440) into wavefront values using Zernike polynomials up to the 8th order. This included Placido-based corneal topography, which allows separation and calculation of corneal and internal wavefront aberrations. To evaluate the optical quality of the IOLs, the postoperative RMS of the internal wave aberration for HOAs Z(3 % n % 8); vertical and horizontal coma Z(3,G1); vertical and oblique trefoil Z(3,G2);

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Oculus Optikger€ate GmbH) was used to verify the level of intraocular straylight determined by each IOL. The instrument’s internal test field is divided into 2 hemifields. In 1 hemifield, straylight is induced by a peripheral light source. The other hemifield shows a counterphase flickering of variable intensity. The patient’s task is a forced-choice comparison between the 2 half fields to decide which flickers more strongly. This method is known as compensation comparison.6,7 The test was set at range E (moderate) for all patients, and the logarithmic values of the straylight parameter, denoted as log(s), were collected. The Esd value, defined by the straylight meter as the SD of the individual evaluation, was also recorded. Dysphotopsia was assessed by the QoV questionnaire score. The QoV is a validated Rasch-adjusted questionnaire in which patients are asked to rate 10 dysphotopsia items depicted in standard photographs. Patients score each item (0, 1, 2, or 3) in relation to how frequent, severe, and bothersome their symptoms are (30 items in total). Responses to the QoV questionnaire were converted to a linear interval scale (0 to 100). Lower Raschweighted QoV scores indicate a better quality of vision. The spectacle-dependence questionnaire asked patients to rate how often (always, sometimes, or never) they used spectacles for any purpose, for distance vision (driving, reading text on television), for intermediate vision (computer work, working with hands), and for near vision (reading, fine near work). The accuracy of IOL power calculation was evaluated by collecting the postoperative wavefront-based objective spherical equivalent (SE) at a 4.0 mm pupil diameter measured with the refractive power/corneal analyzer system and then comparing it with the expected SE value calculated using optical low-coherence reflectomy. Unexpected eye examination findings and intraoperative or postoperative complications were recorded prospectively on clinical record forms. Figure 1. Study flow diagram (CDVA Z corrected distance visual acuity; DCIVA Z distance-corrected intermediate visual acuity; DCNVA Z distance-corrected near visual acuity; EROV Z extendedrange-of-vision; IOL Z intraocular lens; MONOF Z monofocal; MTF Z modulation transfer function; PSF Z point spread function; Pts Z patients; TRIF Z trifocal; UDVA Z uncorrected distance visual acuity; UIVA Z uncorrected intermediate visual acuity; UNVA Z uncorrected near visual acuity).

coma-like aberrations Z(3,G1), Z(5,G1), and Z(7,G1); and primary spherical aberration Z(4,0) at 3.0 mm and 5.0 mm pupil diameters were calculated. To assess the combined performance of the IOLs with the cornea, the postoperative RMS of the total (ocular) wave aberration for lower-order aberrations (LOAs) Z(1 % n % 2); HOAs Z(3 % n R 8); coma Z(3,G1); trefoil Z(3,G2); coma-like Z(3,G1), Z(5,G1), and Z(7,G1); and primary spherical aberration Z(4,0) at 3.0 mm and 5.0 mm pupil diameters were measured. Furthermore, the Strehl ratio of the point-spread function (PSF) and the modulation transfer function (MTF) from the postoperative RMS of the total (ocular) wave aberration Z(1 % n % 8) were assessed at 3.0 mm and 5.0 mm pupil diameters. The PSF describes the quality response of an imaging system to a light-point source and is expressed by the Strehl ratio, with 1 indicating a perfect optical system. The MTF of an IOL is a measure of its ability to transfer the contrast at a particular resolution from the object to the image. In other words, the MTF is a way to incorporate resolution and contrast into a single specification. As the spatial frequency of the test target increases, it becomes increasingly difficult for the IOL to provide efficient transfer and, as a result, the MTF decreases. The MTF was plotted against a spatial frequency from 0 to 40 cycles per degree (cpd). The visual effect of light scattered around a bright light source is called straylight.5 In this study, a straylight meter (C-Quant,

Masking This study was double masked. Patients were not told which study IOL was implanted until all data had been collected and recorded at the outcome assessment. Examiners performing refractive outcome assessments were blinded to which IOL was implanted to minimize a risk for bias caused by IOL identification during examinations. Statisticians were also masked to IOL identity until after the primary outcome data were analyzed. Sample Size The calculation of the required sample size was based on the primary outcome parameter of monocular DCNVA at 40 cm under photopic conditions. A previous study of the same monofocal IOL used in this study found a monocular DCNVA of 0.37 logMAR.8 Considering an SD of 0.2, a difference of 0.2 logMAR was assumed to be clinically significant. Based on these assumptions, an a of 0.01, and a power of 0.9, it was calculated that 32 eyes were required in each group. Assuming a dropout rate of 20%, this resulted in a total requirement of 117 eyes. Fellow eyes were considered independent for statistical purposes. Statistical Analyses Statistical analyses were performed using Stata for Windows software (version 14.0, Statacorp LP). A P value less than 0.05 was considered statistically significant. All tests were 2 tailed. Intergroup comparisons of baseline characteristics were performed using the chi-square test and 1-way analysis (ANOVA) for categorical and continuous variables, respectively. One-way ANOVA was used to compare the primary and secondary outcomes and the QoV results 4 months after surgery. Post hoc analysis was adjusted using the Bonferroni correction. The relationship between the QoV score and aberrations with each treatment was tested using a Pearson correlation test. Furthermore, ANOVA for repeated measures was used to examine the within-group and between-group effects Volume 43 Issue 6 June 2017

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Table 1. Intragroup comparison of baseline characteristics. P Value

Parameter Patients/eyes (n)

TRIF

EROV

MONOF

TRIF Vs EROV*

TRIF Vs MONOF*

EROV Vs MONOF†

20/40

20/40

20/40

1.00

1.00

1.00

66.0 G 5.5

67.0 G 8.5

68.0 G 4.7

1.00

.47

1.00

Sex, n (%) Female Male

9 (45) 11 (55)

11 (55) 9 (45)

8 (40) 12 (60)

.46 .46

.9 .9

.32 .32

Race, n (%) White Black

19 (95) 1 (5)

20 (100) 0

20 (100) 0

.64 .64

.64 .64

1.00 1.00

Mean age (y)

Monocular visual acuity Mean CDVA (logMAR)

0.44 G 0.05

0.40 G 0.07

0.45 G 0.05

1.00

1.00

1.00

Optical low-coherence reflectometry Mean AL (mm) Mean ACD (mm) Mean IOL power (D) Mean expected SE refractive error (D)

23.57 G 0.80 2.96 G 0.35 22.33 G 2.25
0.20 G 0.25

23.40 G 0.87 2.99 G 0.38 22.63 G 2.35
0.25 G 0.27

23.50 G 0.64 2.97 G 0.35 22.35 G 2.55
0.18 G 0.25

1.00 1.00 1.00 1.00

1.00 1.00 1.00 1.00

1.00 1.00 1.00 1.00

Rotating Scheimpflug camera system Mean K reading (TNP) Mean astigmatism (TNP)

42.88 G 1.50
0.52 G 0.26

42.24 G 1.15
0.55 G 0.28

42.18 G 1.50
0.54 G 0.25

.64 1.00

1.00 1.00

.64 1.00

2.77 G 0.45 4.16 G 0.70 0.15 G 0.73 0.41 G 0.02 0.16 G 0.08

3.02 G 0.49 4.37 G 0.78 0.15 G 0.74 0.41 G 0.03 0.17 G 0.08

2.92 G 0.53 4.45 G 0.47 0.12 G 0.62 0.41 G 0.03 0.15 G 0.03

.18 .73 1.00 1.00 1.00

1.00 1.00 .5 1.00 1.00

.9 .73 .5 1.00 .78

Refractive power/corneal analyzer Mean photopic pupil (mm) Mean mesopic pupil (mm) Mean angle k (mm) Mean IAI Mean RMS corneal HOAs (mm)

ACD Z anterior chamber depth; AL Z axial length; CDVA Z corrected distance visual acuity; EROV Z extended-range-of-vision group; HOAs Z higher-order aberrations; IAI Z irregular astigmatism index; IOL Z intraocular lens; K Z keratometry; logMAR Z logarithm of the minimum angle of resolution; MONOF Z monofocal group; RMS Z root mean square; SE Z spherical equivalent; TNP Z true net power; TRIF Z trifocal group Means G SD *Bonferroni post hoc test † F test

on the dependent variable. The ANOVA was repeated separately, considering MTF and defocus as dependent variables. Spatial frequency and the increasing diopters were used to define the within-group variability, whereas treatments (types of IOLs) represented the between-group variability. Assumptions of repeated measures were tested; when the sphericity assumption was violated, Greenhouse-Geisser adjustments were applied.

RESULTS Seventy-six patients (152 eyes) were assessed for study eligibility between September 2015 and January 2016 (Figure 1). Twenty patients (40 eyes) in each arm of the study (N Z 60 patients, 120 eyes) completed the outcome assessment. There were no statistically significant intragroup differences in baseline characteristics for eyes assigned to any arm of the study (Table 1). All recruited patients completed the study after randomization. There were no dropouts after the IOL implantation in the first eye. Unexpected eye examination findings and complications were not observed. No patient required an IOL explantation.

Primary Outcome Measure

Four months after the second eye surgery, the DCNVA was significantly better in the trifocal group than in the extended-range-of-vision group. Both multifocal IOL groups had better results than the monofocal group (Table 2). Volume 43 Issue 6 June 2017

Secondary Outcome Measures

No differences were found in UDVA and CDVA between the multifocal IOL groups or in comparing them with the monofocal group. For intermediate vision was better than in the multifocal IOL groups than in the monofocal IOL group; however, there was no statistically significant difference in DCIVA between the 2 multifocal groups. For near vision, the UNVA and DCNVA were significantly better in the trifocal group than in the extended-range-of-vision group and both multifocal IOLs were better than the monofocal IOL (Table 2). The evaluation of the defocus curve under photopic circumstances with the 3 IOLs showed a significant main effect for diopters, for treatments, and for interaction (all P % .001). In particular, visual acuity was statistically significantly better with the trifocal IOL than with the extended-range-of-vision IOL for a vergence of
1.5 D and from
2.5 to
4.0 D. Visual acuity was significantly better in the multifocal IOL groups than in the monofocal group for defocus vergences from
1.0 D to
4.0 D (Figure 2). The obtained SE did not differ statistically between the 3 groups. Findings were similar when comparing the difference between the expected and obtained SE or the amount of postoperative LOAs (Table 2). Intraocular aberrations at a 3.0 mm pupil diameter did not differ statistically between groups, except for the RMS of trefoil, which was higher in the monofocal group

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Table 2. Intragroup comparison of outcomes 4 months postoperatively. P Value

Mean ± SD TRIF (40 Eyes)

EROV (40 Eyes)

MONOF (40 Eyes)

TRIF Vs EROV*

TRIF Vs MONOF*

EROV Vs MONOF†

0.00 G 0.04
0.01 G 0.01 0.23 G 0.07 0.13 G 0.07 0.02 G 0.06 0.01 G 0.04
0.19 G 0.04
0.21 G 0.04

0.03 G 0.05
0.01 G 0.02 0.27 G 0.08 0.16 G 0.07 0.07 G 0.08 0.07 G 0.07
0.23 G 0.03
0.28 G 0.04

0.02 G 0.06
0.01 G 0.02 0.42 G 0.09 0.29 G 0.11 0.38 G 0.10 0.32 G 0.09
0.19 G 0.07
0.23 G 0.04

.08 1.00 .04z .37 .05z .005z .12 .08

.4 1.00 .001z .001z .001z .001z 1.00 .32

1.00 1.00 .001z .001z .001z .001z .12 .08

Retinal straylight Straylight meter (log units) Esd

0.87 G 0.20 0.06 G 0.01

0.86 G 0.21 0.05 G 0.02

0.82 G 0.22 0.06 G 0.02

1.00 1.00

.9 1.00

1.00 1.00

Intraocular aberrations (3.0 mm PD) RMS higher-order Z (3 % n R 8) (mm) RMS vertical C horizontal coma Z (3,G1) (mm) RMS vertical C oblique trefoil Z (3,G2) (mm) RMS coma-like Z (3,G1; 5,G1; 7,G1) (mm) RMS primary spherical Z (4,0) (mm)

0.10 G 0.04 0.04 G 0.02 0.06 G 0.05 0.06 G 0.02 0.02 G 0.15

0.10 G 0.02 0.03 G 0.02 0.05 G 0.03 0.07 G 0.02 0.04 G 0.14

0.11 G 0.05 0.04 G 0.02 0.08 G 0.05 0.06 G 0.02 0.03 G 0.02

1.00 .63 .9 1.00 .01z

1.00 1.00 .32 1.00 .75

1.00 .12 .02z .9 .20

Intraocular aberrations (5.0 mm PD) RMS higher-order Z (3 % n R 8) (mm) RMS vertical C horizontal coma Z (3,G1) (mm) RMS vertical C oblique trefoil Z (3,G2) (mm) RMS coma-like Z (3,G1; 5,G1; 7,G1) (mm) RMS primary spherical Z (4,0) (mm)

0.36 G 0.20 0.14 G 0.08 0.17 G 0.15 0.21 G 0.11 0.14 G 0.07

0.46 G 0.14 0.16 G 0.08 0.15 G 0.09 0.20 G 0.14 0.24 G 0.07

0.39 G 0.18 0.15 G 0.08 0.22 G 0.16 0.20 G 0.15 0.14 G 0.07

.001z 1.00 1.00 1.00 .005z

.7 1.00 .14 1.00 1.00

.05z 1.00 .32 1.00 .005z

Total ocular aberrations (3.0 mm PD) RMS lower-order (1 % n R 2) (mm) RMS higher-order Z (3 % n R 8) (mm) RMS vertical C horizontal coma Z (3,G1) (mm) RMS vertical C oblique trefoil Z (3,G2) (mm) RMS coma-like Z (3,G1; 5,G1; 7,G1) (mm) RMS primary spherical Z (4,0) (mm) Strehl ratio of PSF MTF at 10 cpd MTF at 20 cpd MTF at 30 cpd MTF at 40 cpd

0.22 G 0.07 0.10 G 0.06 0.02 G 0.14 0.07 G 0.45 0.04 G 0.02 0.02 G 0.09 0.03 G 0.05 0.20 G 0.09 0.08 G 0.03 0.05 G 0.01 0.44 G 0.02

0.18 G 0.09 0.11 G 0.05 0.02 G 0.02 0.08 G 0.05 0.04 G 0.02 0.03 G 0.03 0.02 G 0.01 0.16 G 0.09 0.06 G 0.03 0.06 G 0.01 0.36 G 0.02

0.25 G 0.08 0.12 G 0.05 0.03 G 0.09 0.10 G 0.13 0.05 G 0.02 0.04 G 0.06 0.02 G 0.01 0.19 G 0.08 0.09 G 0.03 0.05 G 0.09 0.42 G 0.02

.26 1.00 1.00 1.00 1.00 .30 .38 .48 .06 .14 .20

.47 1.00 1.00 .24 1.00 .06 .62 1.00 .67 1.00 .56

.007z 1.00 1.00 .14 .9 1.00 1.00 .27 .71 .50 1

Total ocular aberrations (5.0 mm PD) RMS lower-order (1 % n R 2) (mm) RMS higher-order Z (3 % n R 8) (mm) RMS vertical C horizontal coma Z (3,G1) (mm) RMS vertical C oblique trefoil Z (3,G2) (mm) RMS coma-like Z (3,G1; 5,G1; 7,G1) (mm) RMS primary spherical Z (4,0) (mm) Strehl ratio of PSF MTF at 10 cpd MTF at 20 cpd MTF at 30 cpd MTF at 40 cpd

0.60 G 0.18 0.28 G 0.11 0.08 G 0.04 0.17 G 0.09 0.20 G 0.02 0.06 G 0.05 0.08 G 0.04 0.60 G 0.17 0.28 G 0.12 0.16 G 0.08 0.12 G 0.06

0.74 G 0.20 0.38 G 0.12 0.15 G 0.09 0.21 G 0.10 0.19 G 0.03 0.11 G 0.07 0.10 G 0.06 0.54 G 0.21 0.29 G 0.12 0.17 G 0.08 0.11 G 0.05

0.60 G 0.20 0.30 G 0.05 0.10 G 0.05 0.16 G 0.09 0.17 G 0.02 0.10 G 0.05 0.10 G 0.10 0.56 G 0.18 0.27 G 0.12 0.16 G 0.07 0.11 G 0.04

.005z .9 0.53 1.00 1.00 1.00

1.00 .24 .27 1.00 .32 .005z 1.00 1.00 1.00 1.00 1.00

.09 .47 .11 1.00 .21 1 1.00 1.00 1.00 1.00 1.00

QoV questionnaire score

12.4 G 0.44

14.0 G 0.42

6.2 G 0.17

.32

.007z

Parameter Visual acuities and refractive data UDVA (logMAR) CDVA (logMAR) UIVA (logMAR) DCIVA (logMAR) UNVA (logMAR) DCNVA (logMAR) Obtained SE refractive error (D) D between expected and obtained SE refractive error (D)

.03z .000z .005z .5 1

.005z

D Z difference; CDVA Z corrected distance visual acuity; cpd Z cycles per degree; DCIVA Z distance-corrected intermediate visual acuity; DCNVA Z distance-corrected near visual acuity; EROV Z extended-range-of-vision group; Esd Z standard deviation of the individual measuring point as defined by the straylight meter; logMAR Z logarithm of the minimum angle of resolution; MONOF Z monofocal group; MTF Z modulation transfer function; n Z radial order of the Zernike polynomial; PD Z pupil diameter; PSF Z point spread function; QoV Z quality of vision; RMS Z root mean square; SE Z spherical equivalent; TRIF Z trifocal group; UDVA Z uncorrected distance visual acuity; UIVA Z uncorrected intermediate visual acuity; UNVA Z uncorrected near visual acuity; Z Z Zernike polynomial *Bonferroni post hoc test † F test z Statistically significant (P ! .05)

than in the extended-range-of-vision group, and primary spherical aberration, which was significantly lower with the trifocal IOL than with the extended-range-of-vision IOL. At a 5.0 mm pupil diameter, the RMS of HOAs was significantly higher with the extended-range-ofvision IOL than with the trifocal or monofocal IOL. Primary spherical aberration was also significantly higher

with the extended-range-of-vision IOL than with the trifocal or monofocal IOL (Table 2 and Figure 3). Total aberrations at a 3.0 mm pupil diameter did not differ statistically, except for the RMS of LOAs, which was higher in the monofocal group than in the extendedrange-of-vision group. At a 5.0 mm pupil diameter, the RMS of LOAs, HOAs, and coma were higher in the Volume 43 Issue 6 June 2017

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For the trifocal IOL, there was a direct correlation between the QoV score and total HOAs at a 3.0 mm pupil diameter (r Z .58, P ! .01) and by the QoV score and LOAs at a 3.0 mm pupil diameter (r Z .41, P ! .01). For the monofocal IOL, there was a direct correlation between the QoV score and primary spherical aberration (r Z .37, P ! .01). No other statistically significant correlations were found for the other aberrations.

Figure 2. Mean binocular visual acuity with correction for distance vision measured 4 months postoperatively. Bars around datapoints correspond to SD (* Z statistically significant difference between the values provided by the 2 multifocal intraocular lenses [P % .05]; dots Z statistically significant difference between the values provided by the 2 multifocal intraocular lenses and the monofocal intraocular lens [P % .05]; DCIVA Z distance-corrected intermediate visual acuity; DCNVA Z distance-corrected near visual acuity; EROV Z extended-range-of-vision group; logMAR Z logarithm of minimum angle of resolution; MONOF Z monofocal group; TRIF Z Trifocal Group.

extended-range-of-vision group than in the trifocal group. Primary spherical aberration was lower in the trifocal and monofocal groups than in the extended-range-of-vision group. There were no statistically significant differences in Strehl ratios and MTF values between the 3 groups (Table 2 and Figures 3 and 4). There was no statistically significant difference in the MTF from 0 to 40 cpd between the IOLs. The MTF had a significant main effect of spatial frequency on the MTF at a 3.0 mm pupil diameter (P % .001) and for interaction (P % .01), but not between treatment groups (P Z .08). Furthermore, there was a significant main effect of spatial frequency on the MTF at a 5.0 mm pupil diameter (P % .001), but not for treatment (P Z .99) or for interaction (P Z .23). Retinal straylight did not differ statistically between the 3 groups (Table 2). The QoV questionnaire mean dysphotopsia score for the 2 multifocal IOLs did not differ, although both scores were significantly higher than the monofocal IOL score (Table 2). Halo was the most frequent visual symptom in both multifocal IOL groups, rated “quite often” by 3 patients (15%) with the trifocal IOL and by 5 patients (25%) with the extended-rangeof-vision IOL (Figure 5). Halo was also the most severe and bothersome visual symptom in both multifocal IOL groups, rated “moderate” and “quite” by 3 patients (15%) with the trifocal IOL and by 4 patients (20%) with the extended-range-of-vision IOL. Both multifocal IOL groups wore spectacles for significantly less time than the monofocal group for general purposes and for near and intermediate tasks. There was no intragroup difference between the multifocal IOLs (Table 3). Volume 43 Issue 6 June 2017

DISCUSSION This prospective randomized controlled study compared 2 diffractive IOL types, the trifocal Panoptix and the extended-range-of-vision Symfony. The visual performance for distance in our study was very similar between the 2 multifocal IOL groups and the monofocal group for the monocular vision test and the binocular vision test. This confirms the findings in other studies9,10 in which the trifocal IOL and the extended-range-of-vision IOL provided excellent distance vision compared with a monofocal IOL. These results, together with the limited SDs, support the high level of optical quality provided by both diffractive technologies. For near vision, the patients who had bilateral cataract surgery with implantation of the trifocal IOL, achieved better visual acuity on all tests (monocular and binocular) than the patients in the extended-range-of-vision group and the monofocal group (P Z .005). The extendedrange-of-vision IOL also performed better than the monofocal IOL.9,10 The lower near-vision performance of the extended-range-of-vision IOL compared with the trifocal IOL is a new finding. However, the literature suggests 2 possible solutions to improve that performance. First is the adoption of an intended micromonovision technique, as suggested by the results in the Concerto Study.11 Second is the implantation of a new extended-range-of-vision IOL based on different optical principles; that is, the Mini Well Ready (Sifi Medtech Srl), which seems to have a larger defocus tolerance.12 At intermediate distance (67 cm), both multifocal IOL groups fared well and better than the monofocal group, with the trifocal IOL achieving better results than the extended-range-of-vision IOL on the binocular defocus test from the 1.5 D add on. The 1.5 D (67 cm) defocus result agrees with the intermediate 60 cm focus value found with the Panoptix IOL in a laboratory-based study.13 This suggests that the better performance by the trifocal IOL for near vision begins from an intermediate distance and is increased by binocular cooperation. Patients in the multifocal IOL groups had statistically better results than patients in the monofocal group in terms of wearing spectacles for any purpose. In contrast to the near-vision test results, patients in the extended-range-ofvision group seemed to be no more spectacle dependent than the trifocal group for near tasks, nor was there a difference in spectacle dependence for all tasks between multifocal IOLs. Spectacle dependence is a subjective appraisal depending on a combination of differences in individual habits and lifestyle in real contexts. Additional factors

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Figure 3. Top left: Postoperative intraocular aberrations provided by the 3 IOLs at the 3.0 mm pupil diameter. Top right: Postoperative intraocular aberrations at 5.0 mm pupil diameter. Middle left: Postoperative total (ocular) aberrations at 3.0 mm pupil diameter. Middle right: Postoperative total (ocular) aberrations at 5.0 mm pupil diameter. Bottom left: Modulation transfer function graph at 3.0 mm pupil diameter. The graph plots the mean values of MTF in the circumferential direction with the contrast transfer function on the vertical axis and the spatial frequency on the horizontal axis. Spatial frequency is expressed by the number of cycles of alternating dark and light bars per degree of visual angle. A cycle refers to 1 complete light and dark bar repetition. The more cpd, the higher the spatial frequency and the level of detail of the image. Bottom right: The MTF graph at 5.0 mm pupil diameter (* Z comparison between groups [P % .05]; C-like Z coma-like aberrations; cpd Z cycles per degree; EROV Z extended-range-of-vision group; HOAs Z higher-order aberrations; logMAR Z logarithm of minimum angle of resolution; LOAs Z lower-order aberrations; MONOF Z monofocal group; TRIF Z trifocal group).

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Figure 4. Slitlamp retroillumination photographs (top) and PSF maps (bottom) of 3 cases of the study at the end of follow-up. A and D refer to a patient implanted with the trifocal IOL, B and E to the extendedrange-of-vision IOL, and C and F to the monofocal IOL. The PSF map describes the response of the eye to a point source. In these maps the PSF denotes the HOAs and LOAs of all components of the eye combined. The wavefront error and the Strehl ratio are calculated for a 5.0 mm pupil diameter to the 8th Zernike order (VD Z vertex distance; WF Z wavefront; ZA Z wavefront-based value of cylinder axis; ZC Z wavefront-based value of cylinder; ZS Z wavefront-based value of sphere).

affecting this perception are the contrast between preoperative near uncorrected difficulties and the generally improved postoperative near vision. This might reduce the effect on day-to-day life compared with the differences found in controlled studies. No other statistically significant differences were observed in the secondary outcome measures of retinal straylight, PSF, and MTF between IOL groups. The PSF has been used to evaluate the optical quality of multifocal IOLs,14,15 although we did not find equivalent published PSF data for multifocal IOLs of a more recent generation. However, a previous study that used the OPD scanning system to compare the PSF of 2 toric IOLs found the values were very similar with a 4.0 mm pupil diameter: 0.05 G 0.02 for the Acrysof IQ SN6AT (Alcon Laboratories, Inc.) and 0.07 G 0.06 for the AT Torbi 709M (Carl Zeiss Meditec AG).16 Image quality might also be affected by the MTF values.17 Although we found no difference in MTF, in contrast, Peng et al.18 found the MTF of the earlier Acrysof Restor SN6AD1 IOL to be lower than with the corresponding monofocal IOL (SN60WF). This means that the Panoptix is probably better than the Restor in terms of MTF. In fact, in a recently published study,19 the Restor IOL showed the poorest low mesopic contrast sensitivity function when compared with a monofocal IOL and 4 other multifocal IOLs (AT LISA tri 839MP, Carl Zeiss Meditec AG; Finevision, Physiol S.A.; Lentis Mplus-LS313, Oculus Optikger€ate GmbH; Acri.LISA 366D, Carl Zeiss Meditec AG). In several clinical conditions, an increase in straylight has been associated with visual difficulties, such as blinding by headlights of oncoming cars, halos around light sources, sensitivity to sunlight, and loss of color vision.5,20 Both

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Figure 5. Multivariate data provided by the QoV test. Ten dysphotopsia symptoms (variables) are represented. Only the observations regarding the frequency of the symptoms are shown (EROV Z extended-range-of-vision group; MONOF Z monofocal group; TRIF Z trifocal group).

multifocal IOLs in our study had the same level of straylight as the monofocal IOL. In a recently published review of the effect of multifocal IOL designs on postoperative ocular straylight,21 the mean straylight value of the 9 multifocal IOL models included was 1.18 G 0.19 log(s), higher than the 0.82 to 0.87 log(s) in our population. A possible explanation could be that a different C-Quant measurement range was chosen. In this study, we used a default level E stimulus only. In addition, Michael et al.22 recommended including only measurements with an Esd lower than 0.12 as a quality index, as we did. Our mean Esd value was approximately one half that value in all the groups, which supports the validity of our data. The optical quality provided by the IOLs at 3.0 mm and 5.0 mm pupil diameter was analyzed through the total and internal wave aberrations. The OPD-Scan II system has

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Table 3. Spectacle-dependence questionnaire (20 patients in each IOL group). P Value

Number (%)

TRIF

EROV

MONOF

TRIF Vs EROV*

TRIF Vs MONOF*

EROV Vs MONOF†

How often do you wear glasses for any purpose? Always Sometimes Never

0 3 (15) 17 (85)

1 (5) 5 (25) 14 (70)

15 (75) 5 (25) 0

.24 .32 .27

.001z .32 .001z

.001z 1.00 .001z

How often do you wear glasses for near tasks (eg, reading print)? Always Sometimes Never

0 2 (10) 18 (90)

1 (5) 4 (20) 15 (75)

20 (100) 0 0

.24 .62 .32

.001z .005z .001z

.001z .001z .001z

How often do you wear glasses for intermediate tasks (eg, computer)? Always Sometimes Never

0 0 20 (100)

0 0 20 (100)

7 (35) 10 (50) 3 (15)

1.00 1.00 1.00

.001z .001z .001z

.001z .001z .001z

How often do you wear glasses for distance tasks (eg, driving)? Always Sometimes Never

0 2 (10) 18 (90)

0 3 (15) 17 (85)

2 (10) 3 (15) 15 (75)

1.00 .82 .90

.62 .82 .82

Question

.62 1.00 .72

EROV Z extended-range-of-vision group; MONOF Z monofocal group; TRIF Z trifocal group *Bonferroni post hoc test † F test z Statistically significant (P ! .05)

been used to study diffractive multifocal IOLs.23,24 It showed similar reproducibility but lower interobserver variability than other wavefront aberrometers.25,26 Total HOAs and intraocular HOAs at a 3.0 mm pupil diameter were not statistically different, meaning that in vivo, the measured quality of vision provided by the Panoptix IOL and the Symfony IOL was comparable to that of a monofocal IOL. Analogously, a recently published study27 found that for a small pupil aperture (R3.0 mm), there was an overlapping of MTF peaks with a trifocal IOL (Finevision) and the Symfony IOL. With a wider 5.0 mm pupil diameter, patients in the extended-rangeof-vision group had significantly higher values of intraocular HOAs and total HOAs than the patients who had the trifocal IOL; in particular, the extended-range-of-vision group had the highest mean value of all 3 groups. In other words, when the pupil became larger, the HOAs increased in the multifocal IOL groups, although less so in the trifocal group. In addition, total coma and primary spherical aberration were better with the trifocal IOL than with the extended-range-of-vision IOL. The different IOL design of the Panoptix IOL and the Symfony IOL might have a role in this regard. Because spherical aberration is part of HOAs, the negative effect of increased spherical aberration with a 5.0 mm pupil diameter is not to be ignored because it might affect the contrast sensitivity, mainly under mesopic conditions.28 These findings were in contrast to the PSF and MTF, which are indices of quality and were very similar in all 3 groups. The QoV questionnaire to assess visual side effects and quality of vision was developed in 2010.3,29 McAlinden et al.30 recommend using the total score of the test, without assessing the validity of each question per se. The mean score obtained from all the answers provided by our patients was similar in both multifocal IOL groups

and significantly higher than in the monofocal group, suggesting that patients in the multifocal IOL groups had a higher incidence of visual side effects, despite their excellent distance visual acuity. As corroboration, and without breaking down the scores, we noted that a mean of 82.6% (70% to 100 of all tests) of patients in the monofocal group reported no side effects versus a mean of 60.4% (5% to 100% of all tests) of the patients who had multifocal IOLs. This indicates that approximately 20% of patients with multifocal IOLs were aware of 1 or more unwanted visual symptoms. No patient in any of the 3 groups, however, had symptoms reaching the maximum score on the scale. Maurino et al.,3 in a recent comparison of the AT LISA 809M (Carl Zeiss Meditec AG) and the Acrysof Restor SN6AD1, did not find between-group differences in QoV scores and postulated that patient fatigue during assessment and the potential deleterious effect on concentration, responses, and data quality might affect the usefulness of longer questionnaire instruments, such as the 30-item QoV questionnaire. Even with this consideration, the mean percentages of symptoms with the 2 multifocal IOLs in our study were similar and twice as high as those reported by patients with monofocal IOLs, paralleling the mean scores. In summary, our results suggest that the trifocal Acrysof IQ Panoptix and the extended-range-of-vision Tecnis Symfony might be considered for cataract surgery in patients who are interested in presbyopia correction. However, there is no advantage to choosing the Symfony IOL if the Panoptix IOL is available because the trifocal multifocal IOL provided better near visual acuity and there were no differences in visual disturbances between the 2 IOLs. Our results also suggest that despite the technical advancements, the significant perception of visual side effects requires that patients should still be carefully counseled

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about these effects before they have implantation of a multifocal IOL.

13.

WHAT WAS KNOWN  The design of diffractive multifocal IOLs is 1 of the most commonly used to provide correction of presbyopia after cataract surgery. The major limitations of multifocal IOLs are loss of contrast sensitivity, unwanted or disturbing visual effects, and the inability to provide satisfactory vision at an intermediate distance.

14.

WHAT THIS PAPER ADDS

16.

 The trifocal IOL and the extended-range-of-vision IOL provided a distance quality of vision comparable to that of a monofocal IOL. Both multifocal IOL models seemed to be a good option for patients with intermediate-vision requirements, whereas the trifocal IOL might be better for patients with near-vision requirements.  The quality indicators examined in the multifocal IOL groups did not differ, with the exception that there were more aberrations with the trifocal IOL. However, because the significant perception of visual side effects compared with the monofocal group, patients scheduled for multifocal IOL implantation should continue to be counseled about these effects preoperatively.

15.

17.

18.

19.

20.

21.

REFERENCES 1. Gil-Cazorla R, Shah S, Naroo SA. A review of the surgical options for the correction of presbyopia. Br J Ophthalmol 2016; 100:62–70. Available at: http://bjo.bmj.com/content/bjophthalmol/100/1/62.full.pdf. Accessed April 9, 2017 2. Keates RH, Pearce JL, Schneider RT. Clinical results of the multifocal lens. J Cataract Refract Surg 1987; 13:557–560 3. Maurino V, Allan BD, Rubin GS, Bunce C, Xing W, Findl O, for the Moorfields IOL Study Group. Quality of vision after bilateral multifocal intraocular lens implantation; a randomized trial – AT LISA 809M versus AcrySof ReSTOR SN6AD1. Ophthalmology 2015; 122:700–710 4. Retzlaff JA, Sanders DR, Kraff MC. Development of the SRK/T intraocular lens implant power calculation formula. J Cataract Refract Surg 1990; 16:333–340; erratum, 528 5. van den Berg TJTP. On the relation between glare and straylight. Doc Ophthalmol 1991; 78:177–181 6. Franssen L, Coppens JE, van den Berg TJTP. Compensation comparison method for assessment of retinal straylight. Invest Ophthalmol Vis Sci 2006; 47:768–776. Available at: http://iovs.arvojournals.org/article.aspx? articleidZ2163743. Accessed April 9, 2017 7. Coppens JE, Franssen L, van Rijn LJ, van den Berg TJTP. Reliability of the compensation comparison stray-light measurement method. J Biomed Opt 2006; 11:034027 8. Sun Y, Zheng D, Ling S, Song T, Liu Y. Comparison on visual function after implantation of an apodized diffractive aspheric multifocal or monofocal intraocular lens. Eye Sci 2012; 27:5–12. Available at: http://ykxb.ame groups.com/article/view/3615/4325. Accessed April 9, 2017 9. Brito P, Salgado-Borges J, Neves H, Gonzalez-Meijome J, Moneiro M. Light-distortion analysis as a possible indicator of visual acuity after lens exchange with diffractive multifocal intraocular lenses. J Cataract Refract Surg 2015; 41:613–622 10. Pedrotti E, Bruni E, Bonacci E, Badalamenti R, Mastropasqua R, Marchini G. Comparative analysis of the clinical outcomes with a monofocal and extended range of vision intraocular lens. J Refract Surg 2016; 32:436–442 11. Cochener B, for the Concerto Study Group. Clinical outcomes of a new extended range of vision intraocular lens: International Multicenter Concerto Study. J Cataract Refract Surg 2016; 42:1268–1275. Available at: http:// www.jcrsjournal.org/article/S0886-3350(16)30302-9/pdf. Accessed April 9, 2017   12. Domõnguez-Vicent A, Esteve-Taboada JJ, Del Aguila-Carrasco AJ, Ferrers-Mico  R. In vitro optical quality comparison between the Blasco T, Monte

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Mini WELL Ready progressive multifocal and the TECNIS Symfony. Graefes Arch Clin Exp Ophthalmol 2016; 254:1387–1397 Lee S, Choi M, Xu Z, Zhao Z, Alexander E, Liu Y. Optical bench performance of a novel trifocal intraocular lens compared with a multifocal intraocular lens. Clin Ophthalmol 2016; 10:1031–1038. Available at: https://www. ncbi.nlm.nih.gov/pmc/articles/PMC4898421/pdf/opth-10-1031.pdf. Accessed April 9, 2017  JL, Fimia A, Plaza AB. Double-pass system ~ero DP, Alio Moreno LJ, Pin analysis of the visual outcomes and optical performance of an apodized diffractive multifocal intraocular lens. J Cataract Refract Surg 2010; 36:2048– 2055  mez A, Carmona-Gonza lez D, Martõnez-de-la-Casa Castillo-Go JM, Palo mino-Bautista C, Garcõa-Feijoo J. Evaluation of image quality after implantation of 2 diffractive multifocal intraocular lens models. J Cataract Refract Surg 2009; 35:1244–1250 Scialdone A, De Gaetano F, Monaco G. Visual performance of 2 aspheric toric intraocular lenses: comparative study. J Cataract Refract Surg 2013; 39:906–914  JL, Elkady B, Ortiz D, Bernabeu G. Clinical outcomes and intraocular Alio optical quality of a diffractive multifocal intraocular lens with asymmetrical light distribution. J Cataract Refract Surg 2008; 34:942–948 Peng C, Zhao J, Ma L, Qu B, Sun Q, Zhang J. Optical performance after bilateral implantation of apodized aspheric diffractive multifocal intraocular lenses with C3.00-D addition power. Acta Ophthalmol 2012; 90:e586– e593. Available at: http://onlinelibrary.wiley.com/doi/10.1111/j.17553768.2012.02497.x/pdf. Accessed April 9, 2017 Plaza-Puche AB, Alio JL, Sala E, Mojzis P. Impact of low mesopic contrast sensitivity outcomes in different types of modern multifocal intraocular lenses. Eur J Ophthalmol 2016; 26:612–617 van den Berg TJTP, Franssen L, Kruijt B, Coppens JE. History of ocular straylight measurement: a review. Z Med Phys 2013; 23:6–20. Available at: http://www.sciencedirect.com/science/article/pii/S0939388912001420. Accessed April 9, 2017 qabuz G, Reus NJ, van den Berg TJTP. Comparison of ocular straylight after implantation of multifocal intraocular lenses. J Cataract Refract Surg 2016; 42:618–625  ~i I, Picado J, Jubal JS, Gonza lez Michael R, Barraquer RI, Rodrõguez J, Tun Luque JC, van den Berg T. Intraocular straylight screening in medical testing centres for driver license holders in Spain. J Optom 2010; 3:107–114. Available at: http://www.journalofoptometry.org/en/pdf/S1888429610700 157/S300/. Accessed April 9, 2017 ~ero DP. Comparative Mojzis P, Kukuckova L, Majerova K, Liehneova K, Pin analysis of the visual performance after cataract surgery with implantation of a bifocal or trifocal diffractive IOL. J Refract Surg 2014; 30:666–672  Junior N, Alves E, Tadeu M, Hida WT, Pimenta Motta AF, Kara-Jose Cordeiro LN, Nakano CT. Comparison between OPD-Scan results and visual outcomes of monofocal and multifocal intraocular lenses. Arq Bras Oftalmol 2009; 72:526–532. Available at: http://www.scielo.br/pdf/abo/ v72n4/a17v72n4.pdf. Accessed April 9, 2017 Bartsch D-UG, Bessho K, Gomez L, Freeman WR. Comparison of laser raytracing and skiascopic ocular wavefront-sensing devices. Eye 2008; 22:1384–1390. Available at: http://www.nature.com/eye/journal/v22/ n11/pdf/6702901a.pdf. Accessed April 9, 2017 Visser N, Berendschot TTJM, Verbakel F, Tan AN, de Brabander J, Nuijts RMMA. Evaluation of the comparability and repeatability of four wavefront aberrometers. Invest Ophthalmol Vis Sci 2011; 52:1302–1311. Available at: http://iovs.arvojournals.org/article.aspx?articleidZ2126434. Accessed April 9, 2017 Gatinel D, Loicq J. Clinically relevant optical properties of bifocal, trifocal, and extended depth of focus intraocular lenses. J Refract Surg 2016; 32:273–280 Schuster AK, Tesarz J, Vossmerbaeumer U. Ocular wavefront analysis of aspheric compared with spherical monofocal intraocular lenses in cataract surgery: systematic review with metaanalysis. J Cataract Refract Surg 2015; 41:1088–1097 de Wit DW, Diaz JM, Moore TCB, Moore JE. Refractive lens exchange for a multifocal intraocular lens with a surface-embedded near section in mild to moderate anisometropic amblyopic patients. J Cataract Refract Surg 2012; 38:1796–1801 McAlinden C, Pesudovs K, Moore JE. The development of an instrument to measure quality of vision: the quality of vision (QoV) questionnaire. Invest Ophthalmol Vis Sci 2010; 51:5537–5545. Available at: http://iovs.arvo journals.org/article.aspx?articleidZ2126335. Accessed April 9, 2017

OTHER CITED MATERIAL A. Evans S, Royston P, Day S. Minim: allocation by minimisation in clinical trials. Available at https://www-users.york.ac.uk/wmb55/guide/minim.htm. Accessed April 9, 2017

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B. Panoptix Diffractive Optical Design. Alcon internal technical report: TDOC0018723. Effective date: December 19, 2014. C. Abbott Medical Optics, Inc. TECNISÒ Symfony Extended Range of Vision IOL. Z310939, Rev. 03, Revision Date: 10-03-2014. Available at: www. tecnisiol.com/eu/tecnis-symfony-iol/files/symfony-dfu.pdf. Accessed April 9, 2017 D. Alcon Laboratories, Inc. AcrysofÒ IQ aspheric IOL. Product specifications. Available at: https://www.myalcon.com/products/surgical/acrysof-iq-iol/ monofocal-iol-specifications.shtml. Accessed April 9, 2017 E. User Group for Laser Interference Biometry. Optimized IOL constants for the Haag-Streit Lenstar LS 900 calculated from patient data on file (as of Oct 19, 2014). Available at: http://ocusoft.de/ulib/hs/const/lsc1-new.php. Accessed April 9, 2017

Disclosure: None of the authors has a financial or proprietary interest in any material or method mentioned.

First author: Gaspare Monaco, MD Ophthalmology Unit, Fatebenefratelli e Oftalmico Hospital, ASST Fatebenefratelli Sacco, Milan, Italy

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