ARTICLE

Postoperative bilatera

l reading performancewith 4 intraocular lens models:

Six-month resultsJorge L. Ali�o, MD, PhD, G€unther Grabner, MD, Ana B. Plaza-Puche, MSc, Max Rasp, MD,

David P. Pi~nero, PhD, Orang Seyeddain, MD, Jose L. Rodríguez-Prats, MD, PhD,María Jos�e Ayala, MD, PhD, Rocío Moreu, PhD, Melchior Hohensinn, MD,

Wolfgang Riha, MD, Alois Dexl, MD, MSc

Q

P

842

2011 A

ublished

PURPOSE: To compare bilateral reading performance within the first 6 months after implantation of4 intraocular lens (IOL) models.

SETTING: Vissum-Instituto de Oftalmol�ogico de Alicante, Alicante, Spain, and University Eye Clinic,Paracelsus Medical University, Salzburg, Austria.

DESIGN: Comparative case series.

METHODS: Patients had bilateral phacoemulsification and implantation of Acri.Smart 48S monofo-cal, Acrysof Restor SN6AD3 apodized multifocal, Acri.LISA 366D diffractive multifocal, or Rezoomrefractive multifocal IOLs. Bilateral reading performance with and without near correction wasevaluated preoperatively and postoperatively using the Salzburg Reading Desk.

RESULTS: The study comprised 304 eyes of 152 patients 51 to 90 years old. All groups hada significant improvement in uncorrected and corrected distance visual acuities postoperatively(P%.01). The apodized multifocal and diffractive multifocal groups had significantly better uncor-rected reading acuity than the monofocal and refractive multifocal groups 1 month and 6 monthspostoperatively (P<.01). Uncorrected reading speed was significantly worse in the refractivemultifocal group than in the monofocal group at 1 month (P<.01). The monofocal group had thegreatest uncorrected reading distance at 1 month and 6 months (P<.01).

CONCLUSION: Multifocal IOLs with a diffractive component provided a comparable reading perfor-mance thatwassignificantly better than theone obtainedwith refractivemultifocal andmonofocal IOLs.

Financial Disclosure: Drs. Ali�o, Plaza-Puche, Rasp, Pi~nero, Seyeddain, Rodr�ıguez-Prats, Ayala,Moreu, Hohensinn, and Riha have no financial or proprietary interest in any material or methodmentioned. Additional disclosures are found in the footnotes.

J Cataract Refract Surg 2011; 37:842–852 Q 2011 ASCRS and ESCRS

Reading is an essential task in daily life. The loss of thisability limits a person’s independence and signifi-cantly decreases quality of life.1,2 The reestablishmentof reading performance without any form of readingaid is a strong motivation for an increasing numberof presbyopic patients who seek surgical solutions toregain their uncorrected reading ability.3 One optionis cataract surgery with implantation of new-generation intraocular lenses (IOLs), such as multifo-cal IOLs with a refractive, diffractive, or diffractiveapodized design. The goal of modern cataract surgeryis to provide fast, complete visual rehabilitation (fordistance, intermediate, and near) without surgical

SCRS and ESCRS

by Elsevier Inc.

complications and with low postoperative residual re-fractive errors.4 New multifocal IOL designs5 aim togive the patient complete spectacle independence fordistance and near. These IOLs incorporate differentfoci that avoid the visual limitation at near and inter-mediate distances that occurs with classic monofocalIOLs. The latest generation of multifocal IOLs havebeen shown to provide good distance and near func-tional vision without the use of corrective lenses.6,7

There are few studies of reading ability after cataractsurgery with implantation of different IOLmodels.2,8,9

Most are limited to the evaluation of the visual acuityat different distances. However, this type of analysis is

0886-3350/$ - see front matter

doi:10.1016/j.jcrs.2010.11.039

843READING PERFORMANCE WITH 4 IOL MODELS

incomplete when the focus of interest is the functionalvision of the patient. In such cases, it is best to analyzereading performance and the impact of the final visionon the patient’s quality of life.

Analysis of reading performance requires the use ofan appropriate test and a system that automaticallyand independently records the patient’s reading pro-cess. At present, several charts with different scalesand notations (eg, Jaeger, Nieden, Parinaud) are avail-able for testing reading vision.10,11 Some of the chartshave insufficient standardization and precision.A Inan attempt of solve these problems, Radner et al.1,2,12

developed the Radner Reading Charts, which use sen-tence optotypes to standardize the assessment of read-ing acuity and reading speed. The sentences on thecharts were created to minimize variations betweenthe test items and to keep the geometric proportionsas constant as possible to allow accurate, standardizedmeasurements of reading acuity and reading speed atevery viewing distance. Another aid in evaluatingreading vision is the Salzburg Reading Desk,13,14

which was developed for standardized testing of read-ing acuity and reading speed at any distance usingdifferent log-scaled reading charts. Measurement ofreading speed is a psychophysical and objective exam-ination that provides more information about func-tional vision than visual acuity measurement alone.7

The aim of this multicenter study was to evaluatethe uncorrected bilateral reading performance aftercataract surgery and bilateral implantation of different

Submitted: August 23, 2010.Final revision submitted: October 27, 2010.Accepted: November 4, 2010.

From the Department of Refractive Surgery (Ali�o, Plaza-Puche, Pi~nero,Rodr�ıguez-Prats, Ayala, Moreu), Vissum-Instituto de Oftalmol�ogico deAlicante, DivisionofOphthalmology (Ali�o),UniversidadMiguelHern�an-dez, and the Departamento de �Optica (Pi~nero), Farmacolog�ıa yAnatom�ıa, Universidad de Alicante, Alicante, Spain; University EyeClinic (Grabner, Rasp, Seyeddain, Hohensinn, Riha, Dexl), ParacelsusMedical University, Salzburg, Austria.

Additional financial disclosure: Drs. Grabner and Dexl are patentowners of the Salzburg Reading Desk.

Supported in part by a grant from the Spanish Ministry of Health,Instituto Carlos III, Red Tem�atica de Investigaci�on Cooperativa enSalud Patolog�ıa Ocular del Envejecimiento, Calidad Visual y Calidadde Vida, Subproyecto de Calidad Visual (RD07/0062), and aresearch grant from the European Society of Cataract & RefractiveSurgeons.

Corresponding author: Jorge L. Ali�o, MD, PhD, Research,Development and Innovation, Vissum-Instituto de Oftalmol�ogicode Alicante, Avenida de Denia s/n, Edificio Vissum, 03016 Alicante,Spain. E-mail: jlalio@vissum.com.

J CATARACT REFRACT SURG

models of IOLs using the Salzburg Reading Desk withlog-scaled reading charts (ie, German and Spanish ver-sions of the Radner Reading Charts).

PATIENTS AND METHODS

This multicenter prospective randomized controlled clinicalstudy comprised patients having bilateral phacoemulsifica-tion followed by IOL implantation in the capsular bag. Thepatients were recruited from 2 ophthalmology centers. Allpatients were adequately informed and signed a consentform before inclusion. The study adhered to the tenets ofthe Declaration of Helsinki and was approved by the localethical committees of both institutions

The inclusion criteria were age older than 45 years and theneed for bilateral cataract refractive surgery for presbyopiain the presence of significant nuclear sclerosis. Exclusion cri-teria were active ocular disease and illiteracy.

Intraocular Lenses

Each patient was randomly assigned to 1 of the followingIOL groups:

1. Acri.Smart 48S (Carl ZeissMeditec AG), which is a 1-piecespherical foldable acrylic monofocal IOL (monofocalgroup).15 It has a 25% water content in its fully hydratedstate and a hydrophobic surface. This IOL has a bicon-vex–equiconvex 5.5 mm optic and a total diameter of11.0 mm.

2. AcrySof Restor SN6AD3 (Alcon Laboratories, Inc.), whichis a multifocal IOL that combines apodized diffractiveand refractive technologies (apodized multifocalgroup).16–21 The apodized diffractive optic is within thecentral 3.6 mm optic zone of the IOL, which includes 12concentric steps of gradually decreasing (1.3 to 0.2 mm)step heights. The outer part of the optic surrounds theapodized diffractive region and is the refractive area ofthe IOL. It directs light to a distance focal point for largepupil diameters and is dedicated to distance vision.16–21

The IOL has an optic diameter of 6.0 mm and an overalldiameter of 13.0 mm. The IOL is available in powers rang-ing fromC6.00 toC34.00 diopters (D). The near addition(add) at the lens plane is C4.00 D.

3. Acri.Lisa 366D (Carl Zeiss Meditec AG), which is a single-piece aspheric biconvex refractive–diffractive bifocalIOL22 (diffractive multifocal group). This IOL has an opticdiameter of 6.0 mm and an overall diameter of 11.0 mm.The surface is divided into main zones and phase zones;the phase zones assume the function of the steps of dif-fractive IOLs and have a mean refractive power corre-sponding to the zero diffractive power of the mainzones. The IOL power responsible for distance vision isthus refractive and diffractive at the same time. The firstdiffractive power used for near vision is formed by in-phase interference of waves from themain zones. Incidentlight is distributed with 65% to distance focus and 35% tonear focus.22 The near add at the IOL plane is C3.75 D.The IOL design is aspheric to correct for an aberrationof �0.18 mm. The dioptric powers range from plano toC32.00 D.

4. Rezoom (Abbott Medical Optics, Inc.), which is a second-generation refractive multifocal IOL5,23 (refractive multi-focal group). This IOL distributes incident light over 5optical zones; it has a distance-dominant central zonefor distance vision under bright-light conditions (when

- VOL 37, MAY 2011

844 READING PERFORMANCE WITH 4 IOL MODELS

the pupil is constricted). In the refractive profile, the oddzones (1, 3, and 5) are adjusted for far vision and theeven zones (2 and 4) for near vision, giving a theoreticaladd of approximately 3.50 D at the corneal plane. The dis-tribution of light is dependent on pupil size. Approxi-mately 83% of light is directed to the distant focus and17% to the intermediate focus with a 2.0 mm pupil,whereas 60% of light is directed to the distance focus,30% to the near focus, and 10% to the intermediate focuswith a 5.0 mm pupil.

Surgical Technique

All surgeries were performed by 1 of 3 experienced sur-geons (J.L.A., J.L.R-P., G.G,) using a standard suturelessmicroincision cataract surgery technique. Surgery was per-formed using topical anesthesia (J.L.A., J.L.R-P.) or peribul-bar anesthesia (G.G.). Adequate dilation was obtained byintracameral mydriasis. The incision was placed on the axisof the positive corneal meridian (J.L.A., J.L.R-P.) or superiorcorneoscleral at the 12 o’clock position (G.G.). The Acri.Lisa366D and Acri.Smart 48S IOLs were implanted using anAcri.Glide hydraulic injector (Carl Zeiss Meditec AG), theAcrysof Restor SN6AD3 IOL was implanted using a Mon-arch II injector (Alcon Laboratories, Inc.), and the RezoomIOL was implanted using an Emerald injector (Abbott Med-ical Optics, Inc.). Postoperative topical therapy includedofloxacin 0.3% (Exocin) and dexamethasone 0.1% (Maxidex)(J.L.A., J.L.R-P.) or ofloxacin 0.3% (Floxal), prednisolone ace-tate 0.5% (Ultracortenol), and ketorolac tromethamine 0.5%(Acular) (G.G.).

Preoperative and Postoperative Examinations

Preoperatively, all patients had a full ophthalmologic ex-amination including refractive status, Snellen distance visualacuity at distance and nearwith andwithout the correspond-ing spherocylinder correction (sphere and cylinder fordistance and distance refraction C add for near), anteriorsegment slitlamp evaluation, corneal topography (Costru-zione Strumenti Oftalmici or the Keratron Scout, Optikon2000), tonometry, and fundoscopy.

Reading performance was evaluated using the SalzburgReading Desk.13 The following examinations were mea-sured: reading acuity at best distance (ie, most comfortabledistance for reading), reading speed (speed associated withmaximum reading acuity), and the smallest print size thatcould be read with a minimum reading speed of 80 wordsper minute (wpm), which represents the lower limit for rec-reational sense-capturing reading.10,24 The reading desk au-tomatically measures the reading time, reading distance,reading acuity, and reading speed using log-scaled readingcharts and angulation of the reading board. Patients choosetheir subjectively convenient reading distance, allowingevaluation of everyday reading abilities. The reading deskuses 2 high-frequency repro-lights for a constant illuminancelevel of 500 lux,25 2 video cameras that measure reading dis-tance by stereophotogrammetry, and a reading board witha variable angle (0 to 40 degrees). Also recorded and evalu-ated was the maximum reading speed, which is the maxi-mum value of reading speed recorded during the wholereading test (after the patient reads all sentence optotypesof the Radner charts). All measurements of reading perfor-mance were performed with and without the correction fornear conditions (distance refraction C add).

J CATARACT REFRACT SURG

Snellen charts at 6 mwere used to evaluate distance visualacuity with a mean illumination on the surface of the chart ofapproximately 2237 lux. The Radner Reading Charts1,2,12,26

were used to assess near visual acuity. The charts allow eval-uation of reading acuity in logRAD units (equivalent to log-MAR notation, but for reading performance testing) andreading speed (wpm).

Postoperative visits were scheduled at 1 day and 1 and 6months. The examination protocol at 1 month and 6 monthswas identical to the preoperative protocol.

The term corrected in results reporting designates the pa-rameters that were measured with the correction obtainedby refraction in a trial frame (near refraction for readingparameters).

Statistical Analysis

Statistical analysis was performed using SPSS for Win-dows software (version 15.0.1, SPSS, Inc.). The mean valuesand standard deviations (SDs) were calculated for every pa-rameter. Normal distribution of all data samples was firstchecked by the Kolmogorov-Smirnov test. Parametric analy-sis was possible; thus, the Student t test for paired data wasused for all parameter comparisons between preoperativeand postoperative examinations or between consecutivepostoperative visits. When parametric analysis was notpossible, the Wilcoxon rank-sum test was used to assessthe significance of differences between preoperative andpostoperative data; in all instances, the level of statistical sig-nificance was the same (P!.05).

Regarding comparisons between the IOL groups, 1-wayanalysis of variance (ANOVA) with Bonferroni post hoccomparison procedure was used when parametric analysiswas possible. If variances were not homogeneous (checkedby the Levene test), Tamhane post hoc analysis was used.When parametric analysis was not possible, the Kruskal-Wallis test was used to compare the IOL groups, with thesame level of statistical significance (P!.05). For post hocanalysis, the Mann-Whitney test with the Bonferroni adjust-ment was used to avoid an experimental error rate.

RESULTS

The study comprised 304 eyes of 152 patients withamean age of 71.32G 8.93 years (range 51 to 90 years).108 eyes had surgery at Vissum Alicante and 196 atParacelsus Medical University, Salzburg.

Table 1 shows the preoperative characteristics in the4 IOL groups. There were no statistically significantdifferences between groups in any parameter exceptrefractive cylinder and corrected distance visual acuity(CDVA) (P%.03, Kruskal-Wallis), with a trend towarda larger preoperative cylinder and better CDVA in thediffractive multifocal group. These differences werethe result of the randomization process and do not rep-resent selection bias.

Distance Visual Acuity and Refraction

Table 2A and Table 2B show the postoperativevisual and refractive outcomes at 1 month and6 months, respectively. All 4 IOL groups had

- VOL 37, MAY 2011

Table 1. Comparative preoperative patient characteristics between IOL groups.

Parameter

Intraocular Lens Group

P ValueMonofocal(n Z 72)

Apodized Multifocal(n Z 78)

Diffractive Multifocal(n Z 84)

Refractive Multifocal(n Z 70)

Age (y)Mean G SD 70.18 G 9.35 70.82 G 10.25 70.05 G 9.06 74.23 G 7.06 .17*Range 51, 84 51, 90 52, 88 57, 87

UDVA (logMAR)Mean G SD 0.80 G 0.48 0.62 G 0.33 0.61 G 0.32 0.71 G 0.46 .102†

Range 0.10, 2.00 0.10, 1.30 0.10, 1.78 0.10, 2.00Sphere (D)

Mean G SD C1.03 G 2.81 C0.67 G 2.18 C1.45 G 1.95 C0.88 G 2.35 .16†

Range �9.00, C7.75 �4.75, C5.50 �5.5, C4.0 �7.00, C4.75Cylinder (D)

Mean G SD �0.61 G 0.81 �0.48 G 0.59 �0.63 G 0.68 �0.41 G 0.50 .03†

Range �4.50, 0.00 �2.50, 0.00 �5.00, 0.00 �2.00, 0.00CDVA (logMAR)

Mean G SD 0.26 G 0.22 0.23 G 0.22 0.14 G 0.15 0.29 G 0.22 !.01†

Range �0.08, 1.00 0.00, 0.92 �0.10, 0.52 0.00, 0.90Mean K (D)

Mean G SD 43.77 G 1.42 43.94 G 1.60 43.76 G 1.57 44.06 G 1.42 .586*Range 40.19, 47.71 41.12, 47.93 40.24, 48.13 41.77, 46.91

Corneal astigmatism (D)Mean G SD 0.74 G 0.62 0.67 G 0.41 0.68 G 0.42 0.71 G 0.37 .931†

Range 0.00, 3.80 0.00, 2.02 0.00, 1.75 0.00, 1.56IOP (mm Hg)

Mean G SD 15.04 G 2.25 14.57 G 2.83 14.65 G 2.70 14.71 G 2.93 .625†

Range 10, 20 9, 21 10, 20 13, 21AL (mm)

Mean G SD 23.19 G 1.01 23.03 G 0.92 23.10 G 0.87 22.91 G 0.69 .577*Range 20.77, 25.79 20.85, 24.72 21.30, 25.09 21.83, 24.60

ACD (mm)Mean G SD 3.12 G 0.25 3.04 G 0.36 3.16 G 0.34 3.07 G 0.34 .107*Range 3.81, 2.50 3.74, 2.25 2.47, 4.00 2.25, 3.77

IOL power (D)Mean G SD 21.89 G 2.67 22.26 G 2.33 21.53 G 2.47 22.40 G 2.22 .113†

Range 17.5, 29.5 18.0, 29.5 10.5, 27.0 16.0, 28.0

ACD Z anterior chamber depth; AL Z axial length; CDVA Z corrected distance visual acuity; K Z keratometry; IOLZ intraocular lens; IOP Z intraocularpressure; n Z number of eyes; UDVA Z uncorrected distance visual acuity*One-way analysis of variance†Kruskal-Wallis test

845READING PERFORMANCE WITH 4 IOL MODELS

a significant improvement in UDVA and CDVA aftersurgery (P%.01, Wilcoxon test).

The CDVA at 1 month was statistically significantlyworse in the apodized multifocal group than in themonofocal group (P!.01, Mann-Whitney test). At 6months, the monofocal group had statistically signifi-cantly better UDVA than the apodized multifocalgroup (PZ.02, Mann-Whitney test). In all groups, theUDVA and CDVA did not change significantlybetween 1 month and 6 months postoperatively(PR.07, Wilcoxon test).

Regarding subjective refraction, there were no sig-nificant differences in manifest cylinder between

J CATARACT REFRACT SURG

groups postoperatively (PR.21, Kruskal-Wallis test)(Table 2A). The cylinder was statistically significantlysmaller at 6 months than at 1 month in the monofocalgroup, diffractive multifocal group, and refractivemultifocal group (P%.01, Wilcoxon test) (Table 2B).All groups had a statistically significant reduction insphere after surgery (P%.01, Wilcoxon test). At 1month, the sphere was significantly lower in the dif-fractive multifocal group than in the monofocal andapodized multifocal groups (P%.01, Mann-Whitneytest). In addition, there were no statistically significantdifferences in sphere between 1 month and 6 monthspostoperatively in any group (PR.17, Wilcoxon test).

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Table 2A. Comparison of 1-month postoperative visual and refractive outcomes between the IOL groups.

Parameter

Intraocular Lens Group

P Value*Monofocal Apodized Multifocal Diffractive Multifocal Refractive Multifocal

UDVA (logMAR)Mean G SD 0.12 G 0.15 0.16 G 0.14 0.13 G 0.13 0.13 G 0.13 .08Range �0.10, 0.59 �0.10, 0.82 �0.10, 0.70 �0.10, 0.62

Sphere (D)Mean G SD C0.21 G 0.30 C0.27 G 0.51 �0.01 G 0.50 C0.15 G 0.50 .02Range �1.25, C1.75 �0.75, C2.75 �1.50, C1.00 �1.25, C1.25

Cylinder (D)Mean G SD �0.57 G 0.73 �0.49 G 0.55 �0.38 G 0.42 �0.44 G 0.46 .59Range �4.00, 0.00 �2.75, 0.00 �1.50, 0.00 �2.00, 0.00

CDVA (logMAR)Mean G SD 0.02 G 0.10 0.08 G 0.12 0.05 G 0.10 0.05 G 0.10 .01Range �0.20, 0.30 �0.10, 0.70 �0.10, 0.30 �0.10, 0.40

Corneal astigmatism (D)Mean G SD 0.81 G 0.84 0.70 G 0.48 0.84 G 0.56 0.94 G 0.51 .262Range 0.00, 3.75 0.00, 1.71 0.00, 2.93 0.00, 1.92

CDVA Z corrected distance visual acuity; UDVA Z uncorrected distance visual acuity*Kruskal-Wallis test

846 READING PERFORMANCE WITH 4 IOL MODELS

Reading Acuity

One month postoperatively, there were statisticallysignificant differences between groups in the un-corrected bilateral reading acuity and uncorrectedsmallest print size (P!.01, Kruskal-Wallis test). Theapodized multifocal group and diffractive multifocalgroup had statistically significantly better uncorrectedbilateral reading acuity than the monofocal group(P!.01, Bonferroni test) (Figure 1, A). In addition,

Table 2B. Comparison of 6-month postoperative visual and refractive o

Parameter

Intraoc

Monofocal Apodized Multifocal

UDVA (logMAR)Mean G SD 0.09 G 0.15 0.15 G 0.12Range �0.10, 0.70 �0.10, 0.82

Sphere (D)Mean G SD C0.09 G 0.48 C0.22 G 0.49Range �1.00, C1.25 �1.00, C1.50

Cylinder (D)Mean G SD �0.40 G 0.72 �0.38 G 0.47Range �4.00, 0.00 �2.00, 0.00

CDVA (logMAR)Mean G SD 0.04 G 0.08 0.06 G 0.08Range �0.10, 0.30 �0.10, 0.30

Corneal astigmatism (D)Mean G SD 0.98 G 1.00 0.53 G 0.37Range 0.00, 3.66 0.00, 1.23

CDVA Z corrected distance visual acuity; UDVA Z uncorrected distance visual*Kruskal-Wallis test

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the apodizedmultifocal group and diffractive multifo-cal group had statistically significantly better uncor-rected smallest print size than the monofocal groupand refractive multifocal group (P!.01, Mann-Whitney test) (Figure 1, B).

At 6 months, differences in uncorrected bilateralreading acuity and uncorrected smallest print sizewere similar in the 4 IOL groups (P!.01, Mann-Whitney test) (Figure 1, B). Furthermore, there were

utcomes between the IOL groups.

ular Lens Group

P Value*Diffractive Multifocal Refractive Multifocal

0.12 G 0.11 0.12 G 0.13 .02�0.10, 0.49 �0.10, 0.40

0.05 G 0.47 C0.05 G 0.39�1.25, C1.50 �0.75, C1.00

�0.29 G 0.35 �0.20 G 0.38 .21�1.25, 0.00 �1.00, 0.00

0.06 G 0.10 0.06 G 0.11 .25�0.10, 0.30 �0.10, 0.30

0.63 G 0.42 0.45 G 0.37 .3580.00, 1.63 0.00, 0.93

acuity

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Figure 1. A: Changes in mean uncorrected reading acuity (logRAD ). The error bars represent the SD. B: Changes in mean uncorrected smallestprint size (smallest optotype sizes that could be read at a minimum reading speed of 80 wpm) over time. The error bars represent the SD.C: Changes in mean corrected reading acuity (logRAD) over time. The error bars represent the SD.D: Changes in mean corrected smallest printsize (smallest optotype sizes that could be read at a minimum reading speed of 80 wpm) over time. The error bars represent the SD.

847READING PERFORMANCE WITH 4 IOL MODELS

no statistically significant changes in uncorrectedbilateral reading acuity or uncorrected smallest printsize postoperatively in any group (PR.527, Wilcoxontest).

There were statistically significant differencesbetween groups in corrected reading acuity (PZ.01,Kruskal-Wallis test) and corrected smallest print size(P!.01, Kruskal-Wallis test) 1 month after surgery.The monofocal group had statistically significantlybetter corrected reading acuity than the apodizedmul-tifocal group and refractive multifocal group (P!.01,Mann-Whitney test). The diffractive multifocal grouphad statistically significantly better corrected readingacuity than the apodized multifocal group (P!.01,Mann-Whitney test) (Figure 1, C). The monofocalgroup had statistically significantly better correctedsmallest print size than the apodized multifocal andrefractive multifocal groups (P!.01, Mann-Whitneytest). In addition, the corrected smallest print sizewas significantly higher in the diffractive multifocalgroup than in the apodized multifocal group (P!.01,Mann-Whitney test) (Figure 1, D).

At 6 months, the only statistically significant differ-ences were in corrected reading acuity (P!.01,Kruskal-Wallis test). The monofocal group had signifi-cantlybetter corrected readingacuity than theapodized

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multifocal and diffractive multifocal groups (P%.02,Mann-Whitney test), and the apodized multifocalgroup had significantly worse corrected reading acuitythan the refractive multifocal group (PZ.02, Mann-Whitney test) (Figure 1, C). At 6 months, the apodizedmultifocal group had significantly worse correctedsmallest print size than the other groups (P!.01,Kruskal-Wallis test) (Figure 1, D). Furthermore, therewere no statistically significant changes in correctedreading acuity or corrected smallest print size postoper-atively in any group (PR.27, Wilcoxon test).

Reading Speed and Distance

Table 3A and Table 3B show the postoperative read-ing speed and reading distance outcomes at 1 monthand 6 months, respectively. Regarding reading speed,the only statistically significant differences betweengroups was in uncorrected reading speed 1 month af-ter surgery (P!.01, Kruskal-Wallis test). The refractivemultifocal group had a worse uncorrected readingspeed than the monofocal and apodized multifocalgroups (P!.01, Mann-Whitney test). During the post-operative follow-up, the only significant improvementwas in corrected reading speed in the refractive multi-focal group (P!.01, Wilcoxon test). The maximum

- VOL 37, MAY 2011

Table 3A. Comparison of 1-month postoperative reading speed and reading distance outcomes between IOL groups.

Parameter

Intraocular Lens Group

P ValueMonofocal Apodized Multifocal Diffractive Multifocal Refractive Multifocal

Reading speed (wpm)Uncorrected

Mean G SD 112 G 21 112 G 22 115 G 42 101 G 16 .003*Range 80, 180 80, 170 80, 257 81, 149

Maximum uncorrectedMean G SD 171 G 34 173 G 29 190 G 42 167 G 35 .003†Range 94, 267 117, 248 111, 287 105, 258

CorrectedMean G SD 114 G 25 117 G 26 111 G 31 108 G 22 .105*Range 81, 181 81, 172 80, 209 81, 165

Maximum correctedMean G SD 171 G 34 173 G 37 189 G 49 160 G 31 .04*Range 81, 240 107, 277 80, 312 88, 206

Reading distance (cm)Uncorrected

Mean G SD 41.2 G 8.7 29.8 G 4.4 30.8 G 5.4 36.6 G 7.2 !.001†Range 19.4, 57.4 17.5, 38.9 21.6, 45.3 22.7, 59.0

CorrectedMean G SD 35.8 G 5.6 30.2 G 5.0 29.2 G 4.5 33.8 G 5.1 !.001*Range 21.40, 50.50 18.60, 37.20 18.60, 37.20 24.30, 48.00

wpm Z words per minute*Kruskal-Wallis test†One-way analysis of variance

848 READING PERFORMANCE WITH 4 IOL MODELS

uncorrected reading speed at 1 month was statisticallysignificantly better in the diffractive multifocal groupthan in themonofocal and refractive multifocal groups(P%.02, Bonferroni test). The maximum correctedreading speed was significantly better in the diffrac-tive multifocal group than in the apodized multifocaland refractive multifocal groups (P%.03, Mann-Whitney test). During the postoperative follow-up,there was a statistically significant improvement inmaximum corrected reading speed in the monofocalgroup, apodized multifocal group, and refractive mul-tifocal group (P%.01, Wilcoxon test).

Themonofocal group had the greatest postoperativereading distance with and without correction (P%.02,Mann-Whitney test). The reading distancewith correc-tion decreased significantly in the apodized multifocalgroup (PZ.02, Wilcoxon test).

DISCUSSION

Measurement of reading speed and the smallest printsize is a psychophysical and objective examinationthat provides more information about near functionalvision than near visual acuity measurement alone.2,26

Conventional charts (eg, Jaeger, Snellen, Birkh€auser,Zeiss) assess reading visual acuity only, which is a lim-ited predictor of performance of real-world tasks. This

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was the reason leading to the development of readingperformance–based tests,27,28 which are designed to si-multaneously measure reading acuity and speed. Theaim of the current study was to evaluate the readingperformance in eyes with bilateral implantation of1 of 3 multifocal IOL models and to compare theresults with those in eyes with bilateral monofocalIOLs using a standardized procedure.

First, distance visual outcomeswere evaluated to as-sess the potential refractive correction of the IOLs weevaluated. As expected, all 4 IOL groups had a signifi-cant improvement in distance visual outcomes postop-eratively. This is consistent with findings in otherstudies using the same IOL models.3,16,20,22,29,30 TheUDVA was similar in all groups 1 month postopera-tively; however, at 6 months, the monofocal IOL pro-vided significantly better UDVA than the apodizedmultifocal IOL. All groups also had a significant im-provement in CDVA, with a significantly worse out-come in eyes with the apodized multifocal IOL thanin eyes the monofocal IOL, although the differenceswere of small magnitude and all 4 IOL models pro-vided an excellent distance vision. Regarding subjec-tive refraction, there was a significant reduction inthe manifest sphere after surgery in all groups. In ad-dition, there were no significant differences in postop-erative manifest cylinder between the 4 IOL groups.

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Table 3B. Comparison of 6-month postoperative reading speed and reading distance outcomes between IOL groups.

Parameter

Intraocular Lens Group

P ValueMonofocal Apodized Multifocal Diffractive Multifocal Refractive Multifocal

Reading speed (wpm)Uncorrected

Mean G SD 117 G 26 110 G 30 114 G 28 107 G 25 .09*Range 82, 183 81, 206 81, 206 81, 165

Maximum uncorrectedMean G SD 176 G 32 179 G 41 186 G 40 169 G 29 .12†Range 121, 229 93, 279 111, 268 98, 208

CorrectedMean G SD 112 G 30 114 G 30 119 G 23 120 G 24 .06*Range 81, 209 80, 186 80, 165 81, 170

Maximum correctedMean G SD 190 G 41 184 G 41 183 G 38 185 G 27 .76†Range 120, 298 116, 293 85, 267 150, 293

Reading distance (cm)Uncorrected

Mean G SD 38.9 G 6.5 29.2 G 4.1 30.1 G 3.7 35.3 G 7.1 !.001†Range 27.6, 50.9 22.1, 38.7 24.1, 38.9 19.9, 50.5

CorrectedMean G SD 35.4 G 4.8 28.4 G 5.3 29.2 G 4.0 33.3 G 4.9 !.001†Range 21.8, 42.8 16.0, 38.7 20.1, 35.9 21.4, 44.5

wpm Z words per minute*Kruskal-Wallis test†One-way analysis of variance

849READING PERFORMANCE WITH 4 IOL MODELS

This seems logical because small incisions were usedin all cases; it has been shown that the use of small cor-neal incisions in cataract surgery allows surgeonsexcellent control of postoperative astigmatism.31,32

Reading is an activity of daily life and indispens-able for performing many activities.33 One objectiveof the current study was to compare the postoperativebilateral uncorrected reading performance after cata-ract surgery between the 4 IOL groups using a stan-dardized procedure comprising the SalzburgReading Desk13 and the log-scaled Radner ReadingCharts (Spanish and German versions).25 This proce-dure is reported to be a valid and accurate way ofevaluating reading performance.1 The Radner Read-ing Charts have been used to assess reading perfor-mance with other IOL models.8 In the current study,we found significant differences between groups inuncorrected bilateral reading acuity, which was sig-nificantly better after implantation of the multifocalIOLs with a diffractive component than after monofo-cal IOL implantation. This result is consistent withprevious findings of better near visual performancewith multifocal IOLs than with monofocal IOLs34

and with diffractive multifocal IOLs than with refrac-tive IOLs.20,23 Pupil size has a direct influence on theoutcomes with full-refractive IOLs (pupil-dependentIOLs). In the current study, near visual performance

J CATARACT REFRACT SURG

was tested under photopic conditions because read-ing is usually performed with high levels of illumina-tion. Therefore, pupil size limited the light enteringthe eye to that passing through the distance-dominant central zone, with significantly lessamounts of refracted light by the near zones reachingthe retinal plane. The main reason is that the full-refractive IOL model gave more limited readingperformance than the other 2 multifocal IOLs we eval-uated. One surprising outcome was that the binocularreading distance in the monofocal IOL group was notas far as expected; however, theoretically, the IOLdoes not have the ability to generate good focus fornear vision. However, a previous study15 found thatthis specific monofocal IOL model has somepseudoaccommodative ability, although the specificmechanism is not well understood. Therefore, ouroutcomes should be confirmed in future studies usingother types of monofocal IOLs.

Regarding the smallest print size, the trendwas sim-ilar to that for uncorrected bilateral reading acuity;that is, the multifocal IOLs with a diffractive compo-nent provided better near performance than the refrac-tive multifocal and monofocal IOLs. These findingssupport the claim of better near visual performancewith diffractive-based multifocal IOLs. This is mainlythe result of the good image resolution obtained with

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850 READING PERFORMANCE WITH 4 IOL MODELS

these IOLs, especially at near,35–37 and because diffrac-tive IOLs are less pupil dependent. In contrast, the cor-rected reading acuity and smallest print size weresignificantly better in the monofocal IOL group,although differences were of small magnitude. Aprobable reason for the difference is the significantamount of scattering in eyes with multifocal IOLs38;this scattering affects the spherocylinder-correctedvisual performance. In addition, refractive multifocalIOLs have been shown to induce large magnitudesof ocular higher-order aberrations, which can affectboth distance and near visual performance.37 In ourstudy, the 4 IOL groups were comparable in age, axiallength, IOL power, and keratometry; therefore, differ-ences in reading performance are likely the result ofthe type of IOL implanted.

In concordance with previous studies,9 we foundslower uncorrected reading speed with the refractivemultifocal IOL than with the diffractive-based andmonofocal IOLs. This could be explained by the pooreroptical performance and the pupillary dependence ofrefractive multifocal IOLs.35–37 The uncorrected read-ing speed was similar with the monofocal IOL and thediffractive-based IOLs, as reported inaprevious study.9

Furthermore, the diffractive IOL group had bettermax-imum uncorrected reading speed than the monofocaland refractive multifocal IOL groups. This can be ex-plained by the efficacious correction of the near defocuswith diffractive-based IOLs,6,9,16,17,19–22,29,34 as was thecase with other near reading performance parametersin the current study. In addition, the maximum cor-rected reading speed was better with the diffractivemultifocal IOL than with the apodized and refractivemultifocal models, although corrected reading speedwas similar in all groups. As expected, the best uncor-rected and corrected reading distances (with nearcorrection, sphere C cylinder C add) were with themonofocal IOL because of the absence of multifocality.

We also found improvement in the maximum cor-rected reading speed with the monofocal, apodized,and refractive IOLs and in corrected reading speedwith the refractive multifocal IOL. This finding canbe partially attributed to neural adaptation to the mul-tiple foci generated by the multifocal IOLs and thelearning curve effect that occurs when patients takethe same test again. It has been shown that visualperformance after multifocal IOL implantation canbe significantly accelerated by training programs.39

However, the maximum corrected reading speedalso improved significantly over time with the mono-focal IOL, which theoretically should not have abilityto generate good focus for near vision. However, asstated before, a previous study15 found that thismono-focal IOL model has some pseudoaccommodativeability.

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There were also significant differences between thediffractive IOL models (Acri.Lisa versus Restor) inthe current study. Specifically, the Acri.Lisa grouphad significantly better corrected reading acuity,corrected smallest print size, and maximum correctedreading speed values during the postoperative follow-up. The Acri.Lisa optic may have a more optimizeddesign that allows better spherocylinder-correctedperformance. The Restor IOL has a refractive compo-nent that should have a minimum contribution underphotopic conditions; however, it could have a detri-mental effect on visual quality. Recently, our researchgroup found that eyes with an Acri.Lisa IOL hada larger Strehl ratio and cutoff spatial frequency forthe modulation transfer function than eyes with thesame monofocal and apodized IOLs.40

A potential source of variability in the current studyis that the German and Spanish versions of the Radnercharts evaluate different visual outcomes in someareas.However, this is not likely to have an effect because theGerman and Spanish Radner charts have the same syn-tactical and grammatical complexity and they wereperformed using the same standardized procedure.1,26

Furthermore, the 2 clinics in the current study used thesame patient selection criteria, which included literacyand a minimum education level (primary school).However, this factor should be considered a potentialsource of variability in our study.

We did notmeasure pupil size in this study. Hadwedone so, we would have been able to give a more com-plete report of the outcomes. This could be considereda limitation of the study but not a source of bias in theinterpretation of the outcomes. This is because weconsidered the potential effect of pupil size on theoutcomes obtained with the full refractive IOL model.In addition, the 4 IOL groupswere of a similar age (ageand pupil size are related),41 and 3 of the 4 IOLs are,theoretically, not pupil dependent. Indeed, some yearsago our research group found that the intraocular ab-errations related to pupil size had little effect in eyeswith a Restor IOL.23 Another potential limitation ofthe current study is the inclusion of data from differentsurgeons. However, because the 3 surgeons used thesame surgical protocol, the contribution of the surgeonfactor to potential variability in outcomes should havebeen minimal.

In conclusion, the multifocal IOLs with diffractivecomponent seemed to provide better near visual per-formance and thus significantly better reading acuityand speed than the monofocal and refractive multifo-cal IOLs. Therefore, diffractive multifocal IOLs arean adequate option for cataract patients with very de-manding near visual tasks. Our results also indicatethat for the evaluation of reading performance, at least4 parameters should be evaluated; that is, reading

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851READING PERFORMANCE WITH 4 IOL MODELS

acuity, reading distance, reading speed, and smallestprint size. Standardized measurement of reading per-formance is important for future studies that seek tocompare different types of presbyopic correction.

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OL 37, MAY 2011

First author:Jorge L. Ali�o, MD, PhD

Vissum-Instituto de Oftalmol�ogico deAlicante, Alicante, Spain