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Near and intermediate visual and reading performance of patients with a multifocal apodized diffractive intraocular lens using an electronic reading desk
ARTICLE
Near and intermediate visual and reading performance of patients with a multifocal apodized diffractive intraocular lens using an electronic reading desk Mary S.A. Attia, MD, Ramin Khoramnia, MD, FEBO, Gerd U. Auffarth, MD, PhD, FEBO, Merietta Kirchner, Mike P. Holzer, MD, FEBO
PURPOSE: To functionally evaluate an apodized diffractive multifocal intraocular lens (IOL) using an electronic reading desk (Salzburg Reading Desk). SETTING: University Eye Clinic Heidelberg, Heidelberg, Germany. DESIGN: Prospective case series. METHODS: After implantation of an Acrysof IQ Restor C3.0 diopter (D) multifocal IOL, uncorrected (UDVA) and corrected (CDVA) distance visual acuities, uncorrected (UNVA) and distancecorrected (DCNVA) near visual acuities, and uncorrected (UIVA) and distance-corrected (DCIVA) intermediate visual acuities were determined. Criteria for evaluating reading acuity were the reading speed and print size. Monocular and binocular examinations were performed with the electronic reading desk at fixed distances and at the patient’s preferred near and intermediate distances. In addition, a subjective questionnaire was administered. RESULTS: Forty eyes (20 patients) were enrolled. Monocularly, the medians were UDVA, 0.00 logMAR (range 0.26 to 0.14 logMAR); CDVA, 0.08 logMAR (range 0.16 to 0.24 logMAR); 40 cm UNVA, 0.04 logMAR (range 0.24 to 0.10 logMAR); DCNVA, 0.00 logMAR (range 0.18 to 0.22 logMAR); 80 cm UIVA, 0.15 logMAR (range 0.40 to 0.18 logMAR); DCIVA, 0.16 logMAR (range 0.42 to 0.14 logMAR). The monocular reading desk examinations resulted in an uncorrected reading acuity of 0.11 logMAR (range 0.49 to 0.01 logMAR) at 40 cm and 0.30 logMAR (range 0.48 to 0.00 logMAR) at 80 cm. Patients reported a high rate of spectacle independence and satisfaction in everyday life. CONCLUSION: The C3.0 D IOL provided good postoperative functional results at far and near and improved the visual and reading acuity at an intermediate distance. Financial Disclosures: The International Vision Correction Research Centre has received research grants, travel expenses, and lecture fees from various intraocular lens manufacturers. None of the authors has a financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2016; 42:582–590 Q 2016 ASCRS and ESCRS
The goal of spectacle independence is sought by many refractive and cataract patients. In the past decades, this has been made possible by the development of several refractive procedures and numerous multifocal intraocular lenses (IOLs).1–3 Since the 1980s,1,4,5 different multifocal IOL designs, including the refractive pattern, the diffractive pattern, the refractive–diffractive pattern,1,6 and the apodized 582
Q 2016 ASCRS and ESCRS Published by Elsevier Inc.
diffractive pattern,2,3 were developed to facilitate the performance of different lifestyles. Earlier multifocal IOLs were designed to generate only 2 foci, a far focus and a near focus, thus neglecting the intermediate distance. Nowadays, however, the intermediate or computer distance seems to be equally important as the reading distance for many patients. Newer multifocal IOLs have been developed with a http://dx.doi.org/10.1016/j.jcrs.2015.11.047 0886-3350
READING PERFORMANCE USING AN ELECTRONIC READING DESK AFTER MULTIFOCAL IOL IMPLANTATION
low or moderate near addition (add)7 or with an additional intermediate add3 aimed at improving the intermediate distance. Bifocal IOLs with a low or moderate add could be advantageous because light energy is distributed on only 2 foci, whereas for trifocal IOLs, the generation of 3 foci might be associated with a decrease in the optical quality at the far and near focal points.7 The aim of this study was to evaluate the functional results of a bifocal apodized diffractive IOL (Acrysof IQ Restor SN6AD1, Alcon Surgical, Inc.) with a near add of C3.0 diopters (D), which is considered a moderate near add compared with the previous model, the Acrysof SN6AD3, which has a near add of C4.0 D. The evaluation took place after bilateral implantation of the IOL and included visual and reading performance as well as patient satisfaction, with a focus on the intermediate distance. PATIENTS AND METHODS This prospective nonrandomized clinical study, which took place at the International Vision Correction Research Centre of the University Eye Clinic Heidelberg, Heidelberg, Germany, comprised patients who had implantation the Acrysof IQ Restor multifocal C3.0 D SN6AD1 IOL bilaterally. The implantation was part of a refractive lens exchange procedure (RLE) or part of a cataract surgery. The study was approved by the local ethics committee of the University of Heidelberg, Germany, and was performed in accordance with the tenets of the Declaration of Helsinki. Inclusion criteria were bilateral implantation of the IOL, age 18 years or older, a postoperative expected uncorrected visual acuity of 0.2 logMAR (20/32) or better, and the patient's signature on the informed consent form. Ocular and nonocular exclusion criteria included previous ocular surgeries and other ocular and nonocular pathologies, except for cataract, that could affect the postoperative visual acuity. Patients receiving the toric version of the IOL were not enrolled in the study.
Submitted: August 23, 2015. Final revision submitted: November 12, 2015. Accepted: November 27, 2015.
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Intraocular Lens The single-piece Acrysof IQ Restor multifocal C3.0 D SN6AD1 is a bifocal IOL of hydrophobic acrylic. Its optic has 9 diffractive rings occupying the central 3.6 mm and is characterized by the decreasing step height toward the periphery, the so-called apodization.3 The central diffractive zone is surrounded by a peripheral refractive one aiming at allocating the light energy to the far focus in a dilated pupil. The IOL's near add of 3.0 D corresponds to an add of 2.4 D at spectacle plane, thus contributing to a better visual performance at intermediate distances compared with the previous model if the IOL, with a near add of 4.0 D corresponding to 3.2 D at spectacle plane.
Surgical Technique The surgeries were performed by 2 experienced surgeons (M.P.H, G.U.A.) using topical or general anesthesia. The clear corneal incision at the 12 o’clock position was followed by a manual curvilinear or a femtosecond laser– assisted capsulorhexis. Afterward, standard phacoemulsification was performed. The IOL was implanted in the capsular bag. Postoperative topical medication consisted of a combination of an antibiotic and a steroid agent. For IOL power calculation, the Holladay 18 or the Haigis9 formula with targeted emmetropia was used. For eyes with an axial length less than 22.0 mm or more than 25.0 mm measured on the IOLMaster biometer (Carl Zeiss Meditec), the Haigis formula was used.
Postoperative Examinations The postoperative visit included the evaluation of the visual acuity, reading performance, and patient satisfaction. In addition to the monocular examinations, binocular examinations were performed to evaluate “real-life” binocular performance.
Visual Acuity The uncorrected and distance-corrected visual acuities were determined using Early Treatment Diabetic Retinopathy Study (ETDRS) charts (Precision Vision). The 4 m charts were used for distance vision, the 80 cm charts for intermediate vision, and the 40 cm charts for near vision.
Electronic Reading Desk
From the International Vision Correction Research Centre and David J. Apple Laboratory (Attia, Khoramnia, Auffarth, Holzer), University Eye Clinic, and the Institute of Medical Biometry and Informatics (Kirchner), University of Heidelberg, Heidelberg, Germany. Supported by a grant from the Klaus Tschira Stiftung, Heidelberg, Germany. Presented at the ASCRS Symposium on Cataract, IOL and Refractive Surgery, San Diego, California, USA, April 2015. Corresponding author: Mike P. Holzer, MD, FEBO, University Hospital Heidelberg, Department of Ophthalmology, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany. E-mail: mike.holzer@med. uni-heidelberg.de.
The Salzburg Reading Desk has been used for evaluation of reading performance at fixed distances of 40 cm for near and 80 cm for intermediate visual acuity as well as at the patient's preferred near and intermediate distances. It has been Conformite Europeenne marked in Europe since May 2012. It consists of a laptop computer and a reading desk6,10–13 comprising a high-resolution monitor with 2 universal serial bus cameras and a microphone. Screen illumination, contrast, and inclination can be adjusted to perform measurements under standardized conditions.13 The patients read logarithmically scaled Colenbrander sentences (Precision Vision) while the reading distance is measured continuously using video-stereophotogrammetry.6,11–13 For each separate measurement (ie, for each print size), the mean distance is recorded. Tracking sound waves allows calculation of the reading velocity in words per minute (wpm). In this study, a reading velocity above or equal to
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the threshold of 80 wpm was accepted, which represents the lower limit for recreational sense-capturing reading.11,12,14 A stopwatch incorporated in the device records the reading duration, which is expressed in seconds. The reading performance comprises the reading acuity, which is calculated automatically in logMAR, with consideration of the reading distance in centimeters and the logscaled print size of the smallest readable sentence with a minimum velocity of 80 wpm.
Questionnaire Patients were administered a questionnaire regarding visual perceptions and satisfaction on performing daily activities following IOL implantation. The patients had to rate the occurrence of visual problems on a scale from 0 to 10, of which 0 referred to the complete absence of a problem and 10 corresponded to strong discomfort.
Statistical Analysis The statistical analysis was performed using SPSS software (version 21, SPSS, Inc.) and Medcalc software (version 12.3.0.0, Medcalc Software bvba). With Medcalc, the normality of the samples was tested using the Kolmogorov-Smirnov test. Because of a lack of a normal distribution of some variables, the medians with the interquartile ranges (75th quartile to 25th quartile) are shown. Furthermore, the detection of the statistical significance between paired samples of the binocular examination was performed using the Wilcoxon rank-sum test. These included the statistical comparison between the reading performance results at a fixed test distance and those in the respective preferred one as well as the comparison between the ETDRS visual acuity and the electronic reading desk reading acuity determined for the same distance. For the monocular examinations, the linear mixed model of SPSS software was used to test for statistical significance between the paired samples to take into consideration the correlations between each 2 eyes of the same patient. For both tests, the level of significance was a equal to 5%. The questionnaires were analyzed descriptively. Because this was an explorative study (to the authors’ knowledge, no other peer-reviewed publication had mentioned the examination of this specific IOL with the electronic reading
desk), all patients who met the inclusion criteria were included.
RESULTS Forty eyes of 20 patients with a mean age of 57.95 years G 8.55 (SD) were enrolled in the study. The IOL implantation was part of a RLE procedure in 32 eyes and part of cataract surgery in 8 eyes. Seven eyes had femtosecond laser–assisted surgery based on the patients’ wishes. The mean follow-up was 30.83 G 11.96 months postoperatively. One eye had an AL less than 22.0 mm, and 1 eye had an AL greater than 25.0 mm. Visual Acuity Despite theoretically offering only 2 foci and not offering an intermediate focus, the bifocal apodized diffractive IOL is expected to improve intermediate visual acuity results because its lower add of C3.0 D compared with previous IOL models with a C4.0 D add. Table 1 shows the monocular and binocular visual acuities. Reading Performance For technical reasons, the reading performance measurements at 80 cm could not be performed for 1 patient. Therefore for this distance, the number of patients was reduced to 19. Tables 2A, 2B, 3A, and 3B show the results of the different parameters measured during the monocular and the binocular electronic reading desk examinations with and without distance correction. The differences between the measurements at a fixed distance of 40 cm or 80 cm and the respective preferred distance were tested for statistical significance. The patient's preferred near and intermediate reading distances significantly differed from the respective predetermined ones in all cases.
Table 1. Visual acuity (ETDRS) in 40 eyes of 20 patients at far, intermediate, and near distances. Visual Acuity (LogMAR) Parameter Monocular Median IQR Min, Max Binocular Median IQR Min, Max
UDVA (4 m)
CDVA (4 m)
UIVA (80 cm)
DCIVA (80 cm)
UNVA (40 cm)
DCNVA (40 cm)
0.00 0.09 C0.26, 0.14
0.08 0.11 C0.16, 0.24
C0.15 0.21 C0.40, 0.18
C0.16 0.21 C0.42, 0.14
C0.04 0.13 C0.24, 0.10
0.00 0.12 C0.18, 0.22
0.06 0.13 C0.14, 0.20
0.13 0.09 0.02, 0.24
C0.01 0.15 C0.40, 0.20
C0.07 0.15 C0.26, 0.06
0.03 0.11 C0.08, 0.16
0.07 0.07 C0.08, 0.18
CDVA Z corrected distance visual acuity; DCIVA Z distance-corrected intermediate visual acuity; DCNVA Z distance-corrected near visual acuity; IQR Z interquartile range; UDVA Z uncorrected distance visual acuity; UIVA Z uncorrected intermediate visual acuity; UNVA Z uncorrected near visual acuity
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Table 2A. Median monocular intermediate distance reading performance with the electronic reading desk.*
Parameter Reading acuity (logMAR) Median IQR Smallest readable letter size (log-scaled) Median IQR Reading distance (cm) Median IQR Reading speed (wpm) Median IQR Reading duration (s) Median IQR
Uncorrected Intermediate (80 cm) (n Z 38)
Uncorrected Preferred Intermediate (n Z 40)
P Value
Distance-Corrected Intermediate (80 cm) (n Z 38)
Distance-Corrected Preferred Intermediate (n Z 40)
.079 0.30 0.13
.018
0.21 0.09
0.30 0.01
0.27 0.13
!.001 0.50 0.13
0.80 0.17
79.75 0.88
64.60 1.85
98.00 33.75
102.0 28.25
9.45 4.03
9.60 2.35
P Value
!.001 0.50 0.00
0.63 0.20
79.85 1.15
64.55 2.03
104.00 56.25
97.00 34.00
8.85 4.70
10.05 2.50
!.001
!.001
.579
.059
.488
.158
IQR Z interquartile range; wpm Z words per minute *Statistical differences were calculated for the monocular examination with the mixed model; level of significance: a Z 5%.
Visual Acuity With Early Treatment Diabetic Retinopathy Study Charts Versus Reading Acuity With the Electronic Reading Desk
electronic reading desk reading acuity measurements at the same distances (Table 4).
Binocular ETDRS uncorrected intermediate visual acuity (UIVA), distance-corrected intermediate visual acuity, uncorrected near visual acuity, and distance-corrected near visual acuity (DCNVA) (Table 1) were significantly better than the respective
Questionnaire All 20 patients completed the questionnaire. All patients filled out the questionnaire without glasses. Apart from driving at night, 80% or more of the patients were able to perform all activities without
Table 2B. Median binocular intermediate distance reading performance with the electronic reading desk.*
Parameter Reading acuity (logMAR) Median IQR Smallest readable letter size (log-scaled) Median IQR Reading distance (cm) Median IQR Reading speed (wpm) Median IQR Reading duration (s) Median IQR
Uncorrected Uncorrected Preferred Intermediate Intermediate (80 cm) (n Z 19) (n Z 20)
P Value
Distance-Corrected Distance-Corrected Intermediate Preferred Intermediate (80 cm) (n Z 19) (n Z 20)
.0728 0.18 0.20
.3247
0.19 0.13
0.18 0.13
0.19 0.07
!.0001 0.63 0.30
0.80 0.20
79.70 0.50
63.95 2.15
108.00 51.50
106.50 47.25
8.50 3.35
9.25 4.50
P Value
!.0001 0.63 0.13
0.80 0.09
79.60 1.25
63.90 2.83
109.00 55.00
107.00 52.00
9.00 3.70
9.25 4.20
!.0001
!.0001
.3321
.8288
.3247
.6794
IQR Z interquartile range; wpm Z words per minute *Statistical differences were calculated for the binocular examination with the Wilcoxon rank-sum test; level of significance: a Z 5%.
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Table 3A. Median monocular near distance reading performance with the electronic reading desk.*
Parameter Reading acuity (logMAR) Median IQR Smallest readable letter size (log-scaled) Median IQR Reading distance (cm) Median IQR Reading speed (wpm) Median IQR Reading duration (s) Median IQR
Uncorrected Near (80 cm) (n Z 40)
Uncorrected Preferred Near (n Z 40)
0.11 0.15
0.10 0.16
P Value
Distance-Corrected Near (80 cm) (n Z 40)
Distance-Corrected Preferred Near (n Z 40)
.002
.020 0.10 0.17
0.08 0.11
!.001 0.80 0.25
0.80 0.37
40.0 0.92
39.10 4.65
97.5 32.25
97.50 22.25
9.70 2.93
9.70 2.48
P Value
.001 0.80 0.37
1.0 0.20
39.90 0.62
39.65 3.15
105.00 43.00
92.50 40.75
9.75 3.55
10.50 3.63
.001
.001
.729
.057
.916
.027
IQR Z interquartile range; wpm Z words per minute *Statistical differences were calculated for the monocular examination with the mixed model; level of significance: a Z 5%.
spectacle correction (Figure 1). The most cited complaints were night glare (median rate 5.99) followed by halos (median rate 5.0), vision problems under low light conditions (median rate 3.75), and day glare (median rate 2.29) (Figure 2, A). The questionnaire also proved a high rate of spectacle independence for far, near, and intermediate
distance (Figure 2, B), with a larger range for the independence at near distance. DISCUSSION The increase in intermediate distance activities in everyday life led to an increased need for a
Table 3B. Median binocular near distance reading performance with the electronic reading desk.*
Parameter Reading acuity (logMAR) Median IQR Smallest readable letter size (log-scaled) Median IQR Reading distance (cm) Median IQR Reading speed (wpm) Median IQR Reading duration (s) Median IQR
Uncorrected Near (80 cm) (n Z 20)
Uncorrected Preferred Near (n Z 20)
P Value
Distance-Corrected Near (80 cm) (n Z 20)
Distance-Corrected Preferred Near (n Z 20)
.4648 0.05 0.13
0.03 0.09
.6875 0.01 0.09
0.01 0.050
.0156 0.90 0.24
1.00 0.20
39.95 1.33
39.45 7.43
120.5 41.25
115.50 58.25
8.60 3.18
8.70 3.45
.1250 1.00 0.20
1.00 0.00
40.15 0.67
39.60 3.72
120.00 65.25
120.50 43.00
8.30 4.70
8.20 2.63
.0068
.0469
.5771
.8125
.7002
1.000
IQR Z interquartile range; wpm Z words per minute *Statistical differences were calculated for the binocular examination with the Wilcoxon rank-sum test; level of significance: a Z 5%.
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P Value
READING PERFORMANCE USING AN ELECTRONIC READING DESK AFTER MULTIFOCAL IOL IMPLANTATION
Table 4. Visual acuity with ETDRS charts (Table 1) versus reading acuity with the electronic reading desk (Tables 2A, 2B, 3A, and 3B) at the same distances.* Parameter Intermediate distance (80 cm) Uncorrected monocular examination Distance-corrected monocular examination Uncorrected binocular examination Distance-corrected binocular examination Near distance (40 cm) Uncorrected monocular examination Distance-corrected monocular examination Uncorrected binocular examination Distance-corrected binocular examination
P Value !.001 !.001 .0008 .0004 !.001 .077 .0005 .0002
*Statistical differences were calculated for the monocular examination with the mixed model and for the binocular examination with the Wilcoxon rank-sum test. Level of significance: a Z 5%.
spectacle-independent intermediate vision. To meet the patients’ expectations, different multifocal IOL designs and surgical techniques have been developed, including bifocal IOLs with a low or moderate near add7 (eg, 2.5 D or 1.5 D) and trifocal IOLs that generate 3 foci. Furthermore, an improvement in intermediate vision can be achieved by monofocal IOLs using the micro-monovision technique, where for the dominant eye, emmetropia is targeted and for the nondominant eye, near or intermediate vision correction is targeted. Multifocal IOL optics with a moderate near add
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represent a good solution for not only generating 2 foci for far and near distances but also for improving vision at intermediate distances. The Acrysof IQ Restor multifocal C3.0 D SN6AD1 is considered an IOL with a moderate near add compared with its preceding design, the Acrysof IQ Restor C4.0 D SN6AD3 IOL. Good intermediate visual acuity results have been reported for the Acrysof IQ Restor multifocal C3.0 D SN6AD1 IOL.15–19 With the reduction in the near add from 4.0 D to 3.0 D, an improvement in intermediate visual acuity is sought. These adds correspond to 3.2 D and 2.4 D at the spectacle plane, respectively. Instead of a reading distance of 31 cm from the eye with the 4.0 D near add, a distance of 41 cm from the eye is targeted by the 3.0 D add. Wang et al.19 compared both IOLs and found a higher intermediate visual acuity at 60 cm and a higher 30 cm near visual acuity with the 3.0 D add IOL than with the 4.0 D add IOL. For evaluation of the visual and reading function in near and intermediate distance, we used 2 methods; namely, ETDRS charts and the Salzburg Reading Desk, an electronic reading desk. An advantage of the electronic reading desk is that it allows objective determination of the patients’ convenient near and intermediate distances. Moreover, reading complete sentences reflects the daily-life situation of reading texts on a computer screen or in a book. Furthermore, the electronic reading desk allows the performance of measurements under standardized conditions regarding screen
Figure 1. Questionnaire 1. Performance of various daily activities after bilateral implantation of the multifocal IOL (IOL Z intraocular lens; TV Z television).
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Figure 2. Questionnaire 2. A: Median scores of vision problems and perception of photic phenomena. B: Spectacle independence.
inclination, illumination, and contrast. For multifocal IOLs, the distribution of light energy on several foci would probably lead to impairment of the results under low light and contrast conditions when these settings are changed16; therefore, constant room illumination should also be noted. However, in this study, we focused on performing the examinations under standardized conditions to analyze the results at various distances with respect to the different parameters considered for calculating the reading acuity. This study was performed primarily to evaluate the Acrysof IQ Restor multifocal C3.0 D SN6AD1 IOL. The results of the examination at fixed distances of 40 cm and 80 cm can therefore not be applied to IOLs with other add powers and other apodized IOLs. It would be expected that an IOL with a near add of C4.0 D would result in lower visual acuity at 40 cm and at 80 cm. However, the examination at the preferred distances can be used to compare the preferred distance after the implantation of IOLs with various near adds. Ali o et al.20 published 6-month results and Rasp et al.6 published 12-month results of a comparison of different IOL models, including monofocal, diffractive multifocal,
and refractive multifocal IOLs, after their bilateral implantation. The studies found significantly better reading performance for the diffractive multifocal IOL than for monofocal and refractive multifocal IOLs. To our knowledge, this is the first peer-reviewed published study to examine patients with the Salzburg Reading Desk who had implantation of the Acrysof IQ Restor multifocal C3.0 D SN6AD1 IOL. The reading acuity measurements represent the major part of this study. The examination with the electronic reading desk resulted in medians of the preferred intermediate distance between 63.9 cm and 64.60 cm, whereas the medians of the preferred near distance ranged from 39.10 to 39.65 cm. At the preferred distances, either the same letter size could be read over a shorter duration or a smaller letter size could be read compared with the fixed test distance. However, in some cases an identical or even a lower reading acuity was measured at the preferred distance compared with the respective fixed one. This is caused by consideration of the reading distance for the calculation of the reading acuity. As a consequence, nearly identical reading acuity was achieved at the shorter preferred distances despite the smaller print size. The print size, however, significantly differed between the fixed and the preferred distances for all electronic reading desk examinations except for the binocular DCNVA examination. A limitation of the electronic reading desk could be seen in comparing examinations of a large number of patients, especially when performing the examinations in different languages, because the reading speed can vary individually and according to the speaking habit in different languages. In this study, all examinations were performed in German to ensure similar reading habits. A further limitation of the device is that it automatically shows sentences from a sentence database. If a sentence showed up twice, we repeated the measurements until a new sentence appeared to avoid memorization of the sentences. Only those measurements were saved and used for analysis in which a new sentence had appeared. This, however, causes the examination to be time consuming. Except for the distance-corrected monocular examination at 40 cm, significant differences were evident between all ETDRS results and the respective electronic reading desk reading acuity. The variations between the visual acuity and the reading acuity at the same distances can be explained by differences between reading sentences and reading ETDRS optotypes. When reading ETDRS letters, patients might skip a letter but still read the following ones. In the end, it is the number of correct letters that is evaluated. However, omitting a word when reading sentences is not possible because it slows the reading process,
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leading to a reduction in reading speed to values of less than 80 wpm. Sentences with less than 80 wpm were not considered in the results of this study because this is the threshold for healthy eyes.11,12,14 In a recent study Guo et al.,18 20 patients were examined after bilateral implantation of the SN6AD1 IOL. The examination of the preferred reading distance resulted in a value of 37.6 cm. On the bilateral defocus curve, a plateau was detected between the 2.0 D and the 2.5 D defocus with a visual acuity of more than 0.05 logMAR. This proves good visual acuity not only at the reading distance of 40 cm but also up to a distance of 50 cm from the eye. A similar plateau between 2.0 D and 2.5 D on the defocus curve was also found in several other studies examining the same IOL.16,17 Several studies have evaluated the intermediate distance results of the Acrysof IQ Restor multifocal C3.0 D SN6AD1 IOL. In a study by Lane et al.,17 the ETDRS results after bilateral implantation of the IOL showed a mean 60 cm UIVA of 0.17 G 0.14 logMAR. In another study by Alfonso et al.,15 the 6-month postoperative follow-up yielded UIVA results of 0.080 G 0.092 logMAR at 50 cm, 0.082 G 0.141 logMAR at 60 cm, and 0.165 G 0.111 logMAR at 70 cm. These results match our measurements of a smaller letter size read in the close intermediate distance rather than in the far intermediate distance. Similar values were found in a multicenter study by Kohnen et al.16 In that study, the mean preferred reading distance was 41.0 G 4.0 cm. Six months postoperatively, the binocular near and intermediate visual acuity in 10 cm increments showed a decreasing visual acuity between 40 cm and 70 cm. The lowest intermediate visual acuity was at the 70 cm distance and yielded a mean of 0.20 G 0.14 logMAR. Regarding the intermediate distance functional results of trifocal IOLs, results with the 3.0 D add IOL we studied seem to be comparable. Bilateral implantation of the Finevision IOL in 20 patients by Ali o et al.21 resulted in a mean monocular UIVA of 0.20 G 0.11 logMAR at 80 cm 6 months postoperatively with a visual acuity of 0.19 G 0.08 logMAR at the 1.5 D defocus of the binocular defocus curve. Mojzis et al.22 examined a cohort of 30 patients after the bilateral implantation of the AT Lisa tri 839 MP IOL for intermediate visual acuity in 66 cm. The mean UIVA was 0.08 G 0.10 logMAR. The different multifocal IOL designs have disadvantages; the generation of straylight by the refractive and diffractive ring structures leads to increased glare and halo perception.16 Moreover, the light distribution on 2 or even 3 distances could cause a decrease in contrast sensitivity or difficulty in vision, above all under dim light conditions.16 Therefore, the development of
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new IOL designs aims to ensure spectacle independence at all distances and also to reduce the associated photic phenomena and to keep the decrease in contrast sensitivity to a minimum. Several studies of the Acrysof IQ Restor multifocal C3.0 D SN6AD1 IOL reported photic phenomena and patient satisfaction outcomes similar to ours. Glare and halos were classified as mild16,18 to moderate15 in various studies. Nevertheless, the patients were satisfied and reported high spectacle independence.18,23 The high spectacle independence at far, computer, and near distances were reported in studies,16,24 similar to the results in our study. Furthermore, high satisfaction concerning the performance of daily activities at various distances has been reported.15,16 In conclusion, the Acrysof IQ Restor multifocal C3.0 D SN6AD1 IOL provided good functional results at far and near distances and improved visual and reading performance at the intermediate distance by the near add of C3.0 D. The evaluation of patient satisfaction reflected a high rate of spectacle independence, even at the intermediate distance, and a high rate of satisfaction while performing daily activities at various distances. Despite reported halos and glare, there was no limitation of daily activities, no IOL exchange was required, and 90% of the patients said they would have the surgery with the same IOL model again.
WHAT WAS KNOWN The multifocal C3.0 D add IOL improves near vision and supports intermediate vision by its moderate near add of 3.0 D. WHAT THIS PAPER ADDS The reading acuity measurement reflected the patient’s daily performance on reading texts instead of measuring the visual acuity using single optotypes. The determination of reading acuity up to a minimum reading speed of 80 wpm reflected patient satisfaction in everyday life as it is the lower threshold for recreational reading. The preferred near distance after bilateral implantation of the C3.0 D add IOL almost matched the fixed near distance of 40 cm. However, the preferred intermediate distance differed from the fixed intermediate distance of 80 cm. Reading was more convenient at distances between 60 cm and 70 cm. Patients reported a high rate of spectacle independence, even at intermediate distances.
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REFERENCES 1. Auffarth GU, Dick HB. Multifokale Intraokularlinsen; eine € Ubersicht [Multifocal intraocular lenses; a review]. Ophthalmologe 2001; 98:127–137 2. Kohnen T, Derhartunian V. Apodisierte Diffraktionsoptik. Neues Konzept in der Multifokallinsentechnologie [Apodized diffractive optic. New concept in multifocal lens technology]. Ophthalmologe 2007; 104:899–908 3. Gatinel D, Pagnoulle C, Houbrechts Y, Gobin L. Design and qualification of a diffractive trifocal optical profile for intraocular lenses. J Cataract Refract Surg 2011; 37:2060–2067 4. Auffarth GU, Apple DJ. Zur Entwicklungsgeschichte der Intraokularlinsen [History of the development of intraocular lenses]. Ophthalmologe 2001; 98:1017–1028 5. Keates RH, Pearce JL, Schneider RT. Clinical results of the multifocal lens. J Cataract Refract Surg 1987; 13:557–560 6. Rasp M, Bachernegg A, Seyeddain O, Ruckhofer J, Emesz M, Stoiber J, Grabner G, Dexl AK. Bilateral reading performance of 4 multifocal intraocular lens models and a monofocal intraocular lens under bright lighting conditions. J Cataract Refract Surg 2012; 38:1950–1961 7. Madrid-Costa D, Ruiz-Alcocer J, Ferrer-Blasco T, Garcıazaro S, Monte s-Mico R. Optical quality differences beLa tween three multifocal intraocular lenses: bifocal low add, bifocal moderate add, and trifocal. J Refract Surg 2013; 29:749–754 8. Holladay JT, Prager TC, Chandler TY, Musgrove KH, Lewis JW, Ruiz RS. A three-part system for refining intraocular lens power calculations. J Cataract Refract Surg 1988; 14:17–24 9. Haigis W, Lege B, Miller N, Schneider B. Comparison of immersion ultrasound biometry and partial coherence interferometry for intraocular lens calculation according to Haigis. Graefes Arch Clin Exp Ophthalmol 2000; 238:765–773 € gel H, Wolfbauer M, Grabner G. Device for 10. Dexl AK, Schlo improving quantification of reading acuity and reading speed. J Refract Surg 2010; 26:682–688. Available at: http://www. google.com/url?saZt&rctZj&qZ&esrcZs&frmZ1&sourceZweb &cdZ1&cadZrja&uactZ8&vedZ0CB4QFjAA&urlZhttp%3A% 2F%2Fwww.researchgate.net%2Fprofile%2FAlois_Dexl%2F publication%2F40455105_Device_for_improving_quantification _of_reading_acuity_and_reading_speed%2Flinks%2F0fcfd512 c7fb3726ad000000.pdf&eiZy1Y1VbaZA9DdsASojIDICw&usg ZAFQjCNFKb45mMW3AgwYwLzM9Jqn0-3LWEQ&bvmZbv. 91071109,d.b2w. Accessed January 11, 2016 €ckl T, 11. Dexl AK, Seyeddain O, Riha W, Hohensinn M, Ru Hitzl W, Grabner G. Reading performance after implantation of a modified corneal inlay design for the surgical correction of presbyopia: 1-year follow-up. Am J Ophthalmol 2012; 153:994–1001 €ckl T, Bachernegg A, 12. Dexl AK, Seyeddain O, Riha W, Ru Emesz M, Ruckhofer J, Grabner G. Reading performance and patient satisfaction after corneal inlay implantation for presbyopia correction: two-year follow-up. J Cataract Refract Surg 2012; 38:1808–1816 13. Hirnschall N, Motaabbed JK, Dexl A, Grabner G, Findl O. Evaluation of an electronic reading desk to measure reading acuity in pseudophakic patients. J Cataract Refract Surg 2014; 40:1462–1468
14. Whittaker SG, Lovie-Kitchin J. Visual requirements for reading. Optom Vis Sci 1993; 70:54–65. Available at: http://journals.lww. com/optvissci/Abstract/1993/01000/Visual_Requirements_for_ Reading.10.aspx. Accessed January 11, 2016 ndez-Vega L, Amhaz H, Monte s-Mico R, 15. Alfonso JF, Ferna rcel B, Ferrer-Blasco T. Visual function after implantation Valca of an aspheric bifocal intraocular lens. J Cataract Refract Surg 2009; 35:885–892 16. Kohnen T, Nuijts R, Levy P, Haefliger E, Alfonso JF. Visual function after bilateral implantation of apodized diffractive aspheric multifocal intraocular lenses with a C3.0 D addition. J Cataract Refract Surg 2009; 35:2062–2069 17. Lane SS, Javitt JC, Nethery DA, Waycaster C. Improvements in patient-reported outcomes and visual acuity after bilateral implantation of multifocal intraocular lenses with C3.0 diopter addition: multicenter clinical trial. J Cataract Refract Surg 2010; 36:1887–1896 18. Guo X, Sun Y, Zhang B, Zheng D. Medium-term visual outcomes of apodized diffractive multifocal intraocular lens with C3.00 d addition power. J Ophthalmol 2014:247829. Available at: http://downloads. hindawi.com/journals/joph/2014/247829.pdf. Accessed January 11, 2016 19. Wang Q, Zhao G, Wang Q, Jia W. Visual quality after AcrySof IQ ReSTOR intraocular lens implantation in eyes with high myopia. Eur J Ophthalmol 2012; 22:168–174 JL, Grabner G, Plaza-Puche AB, Rasp M, Pin ~ero DP, 20. Alio Seyeddain O, Rodrıguez-Prats JL, Ayala MJ, Moreu R, Hohensinn M, Riha W, Dexl A. Postoperative bilateral reading performance with 4 intraocular lens models: Six-month results. J Cataract Refract Surg 2011; 37:842–852 JL, Montalba n R, Pen ~a-Garcıa P, Soria FA, Vega21. Alio Estrada A. Visual outcomes of a trifocal aspheric diffractive intraocular lens with microincision cataract surgery. J Refract Surg 2013; 29:756–761 ~ a-Garcıa P, Liehneova I, Ziak P, Alio JL. Outcomes 22. Mojzis P, Pen of a new diffractive trifocal intraocular lens. J Cataract Refract Surg 2014; 40:60–69 23. 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://online library.wiley.com/doi/10.1111/j.1755-3768.2012.02497.x/pdf. Accessed January 11, 2016 24. van der Linden JW, van Velthoven M, van der Meulen I, Nieuwendaal C, Mourits M, Lapid-Gortzak R. Comparison of a new-generation sectorial addition multifocal intraocular lens and a diffractive apodized multifocal intraocular lens. J Cataract Refract Surg 2012; 38:68–73
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First author: Mary S.A. Attia, MD International Vision Correction Research Centre and David J. Apple Laboratory, University Eye Clinic, Heidelberg, Germany
Near and intermediate visual and reading performance of patients with a multifocal apodized diffractive intraocular lens using an electronic reading desk Mary S.A. Attia, MD, Ramin Khoramnia, MD, FEBO, Gerd U. Auffarth, MD, PhD, FEBO, Merietta Kirchner, Mike P. Holzer, MD, FEBO
PURPOSE: To functionally evaluate an apodized diffractive multifocal intraocular lens (IOL) using an electronic reading desk (Salzburg Reading Desk). SETTING: University Eye Clinic Heidelberg, Heidelberg, Germany. DESIGN: Prospective case series. METHODS: After implantation of an Acrysof IQ Restor C3.0 diopter (D) multifocal IOL, uncorrected (UDVA) and corrected (CDVA) distance visual acuities, uncorrected (UNVA) and distancecorrected (DCNVA) near visual acuities, and uncorrected (UIVA) and distance-corrected (DCIVA) intermediate visual acuities were determined. Criteria for evaluating reading acuity were the reading speed and print size. Monocular and binocular examinations were performed with the electronic reading desk at fixed distances and at the patient’s preferred near and intermediate distances. In addition, a subjective questionnaire was administered. RESULTS: Forty eyes (20 patients) were enrolled. Monocularly, the medians were UDVA, 0.00 logMAR (range 0.26 to 0.14 logMAR); CDVA, 0.08 logMAR (range 0.16 to 0.24 logMAR); 40 cm UNVA, 0.04 logMAR (range 0.24 to 0.10 logMAR); DCNVA, 0.00 logMAR (range 0.18 to 0.22 logMAR); 80 cm UIVA, 0.15 logMAR (range 0.40 to 0.18 logMAR); DCIVA, 0.16 logMAR (range 0.42 to 0.14 logMAR). The monocular reading desk examinations resulted in an uncorrected reading acuity of 0.11 logMAR (range 0.49 to 0.01 logMAR) at 40 cm and 0.30 logMAR (range 0.48 to 0.00 logMAR) at 80 cm. Patients reported a high rate of spectacle independence and satisfaction in everyday life. CONCLUSION: The C3.0 D IOL provided good postoperative functional results at far and near and improved the visual and reading acuity at an intermediate distance. Financial Disclosures: The International Vision Correction Research Centre has received research grants, travel expenses, and lecture fees from various intraocular lens manufacturers. None of the authors has a financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2016; 42:582–590 Q 2016 ASCRS and ESCRS
The goal of spectacle independence is sought by many refractive and cataract patients. In the past decades, this has been made possible by the development of several refractive procedures and numerous multifocal intraocular lenses (IOLs).1–3 Since the 1980s,1,4,5 different multifocal IOL designs, including the refractive pattern, the diffractive pattern, the refractive–diffractive pattern,1,6 and the apodized 582
Q 2016 ASCRS and ESCRS Published by Elsevier Inc.
diffractive pattern,2,3 were developed to facilitate the performance of different lifestyles. Earlier multifocal IOLs were designed to generate only 2 foci, a far focus and a near focus, thus neglecting the intermediate distance. Nowadays, however, the intermediate or computer distance seems to be equally important as the reading distance for many patients. Newer multifocal IOLs have been developed with a http://dx.doi.org/10.1016/j.jcrs.2015.11.047 0886-3350
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low or moderate near addition (add)7 or with an additional intermediate add3 aimed at improving the intermediate distance. Bifocal IOLs with a low or moderate add could be advantageous because light energy is distributed on only 2 foci, whereas for trifocal IOLs, the generation of 3 foci might be associated with a decrease in the optical quality at the far and near focal points.7 The aim of this study was to evaluate the functional results of a bifocal apodized diffractive IOL (Acrysof IQ Restor SN6AD1, Alcon Surgical, Inc.) with a near add of C3.0 diopters (D), which is considered a moderate near add compared with the previous model, the Acrysof SN6AD3, which has a near add of C4.0 D. The evaluation took place after bilateral implantation of the IOL and included visual and reading performance as well as patient satisfaction, with a focus on the intermediate distance. PATIENTS AND METHODS This prospective nonrandomized clinical study, which took place at the International Vision Correction Research Centre of the University Eye Clinic Heidelberg, Heidelberg, Germany, comprised patients who had implantation the Acrysof IQ Restor multifocal C3.0 D SN6AD1 IOL bilaterally. The implantation was part of a refractive lens exchange procedure (RLE) or part of a cataract surgery. The study was approved by the local ethics committee of the University of Heidelberg, Germany, and was performed in accordance with the tenets of the Declaration of Helsinki. Inclusion criteria were bilateral implantation of the IOL, age 18 years or older, a postoperative expected uncorrected visual acuity of 0.2 logMAR (20/32) or better, and the patient's signature on the informed consent form. Ocular and nonocular exclusion criteria included previous ocular surgeries and other ocular and nonocular pathologies, except for cataract, that could affect the postoperative visual acuity. Patients receiving the toric version of the IOL were not enrolled in the study.
Submitted: August 23, 2015. Final revision submitted: November 12, 2015. Accepted: November 27, 2015.
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Intraocular Lens The single-piece Acrysof IQ Restor multifocal C3.0 D SN6AD1 is a bifocal IOL of hydrophobic acrylic. Its optic has 9 diffractive rings occupying the central 3.6 mm and is characterized by the decreasing step height toward the periphery, the so-called apodization.3 The central diffractive zone is surrounded by a peripheral refractive one aiming at allocating the light energy to the far focus in a dilated pupil. The IOL's near add of 3.0 D corresponds to an add of 2.4 D at spectacle plane, thus contributing to a better visual performance at intermediate distances compared with the previous model if the IOL, with a near add of 4.0 D corresponding to 3.2 D at spectacle plane.
Surgical Technique The surgeries were performed by 2 experienced surgeons (M.P.H, G.U.A.) using topical or general anesthesia. The clear corneal incision at the 12 o’clock position was followed by a manual curvilinear or a femtosecond laser– assisted capsulorhexis. Afterward, standard phacoemulsification was performed. The IOL was implanted in the capsular bag. Postoperative topical medication consisted of a combination of an antibiotic and a steroid agent. For IOL power calculation, the Holladay 18 or the Haigis9 formula with targeted emmetropia was used. For eyes with an axial length less than 22.0 mm or more than 25.0 mm measured on the IOLMaster biometer (Carl Zeiss Meditec), the Haigis formula was used.
Postoperative Examinations The postoperative visit included the evaluation of the visual acuity, reading performance, and patient satisfaction. In addition to the monocular examinations, binocular examinations were performed to evaluate “real-life” binocular performance.
Visual Acuity The uncorrected and distance-corrected visual acuities were determined using Early Treatment Diabetic Retinopathy Study (ETDRS) charts (Precision Vision). The 4 m charts were used for distance vision, the 80 cm charts for intermediate vision, and the 40 cm charts for near vision.
Electronic Reading Desk
From the International Vision Correction Research Centre and David J. Apple Laboratory (Attia, Khoramnia, Auffarth, Holzer), University Eye Clinic, and the Institute of Medical Biometry and Informatics (Kirchner), University of Heidelberg, Heidelberg, Germany. Supported by a grant from the Klaus Tschira Stiftung, Heidelberg, Germany. Presented at the ASCRS Symposium on Cataract, IOL and Refractive Surgery, San Diego, California, USA, April 2015. Corresponding author: Mike P. Holzer, MD, FEBO, University Hospital Heidelberg, Department of Ophthalmology, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany. E-mail: mike.holzer@med. uni-heidelberg.de.
The Salzburg Reading Desk has been used for evaluation of reading performance at fixed distances of 40 cm for near and 80 cm for intermediate visual acuity as well as at the patient's preferred near and intermediate distances. It has been Conformite Europeenne marked in Europe since May 2012. It consists of a laptop computer and a reading desk6,10–13 comprising a high-resolution monitor with 2 universal serial bus cameras and a microphone. Screen illumination, contrast, and inclination can be adjusted to perform measurements under standardized conditions.13 The patients read logarithmically scaled Colenbrander sentences (Precision Vision) while the reading distance is measured continuously using video-stereophotogrammetry.6,11–13 For each separate measurement (ie, for each print size), the mean distance is recorded. Tracking sound waves allows calculation of the reading velocity in words per minute (wpm). In this study, a reading velocity above or equal to
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the threshold of 80 wpm was accepted, which represents the lower limit for recreational sense-capturing reading.11,12,14 A stopwatch incorporated in the device records the reading duration, which is expressed in seconds. The reading performance comprises the reading acuity, which is calculated automatically in logMAR, with consideration of the reading distance in centimeters and the logscaled print size of the smallest readable sentence with a minimum velocity of 80 wpm.
Questionnaire Patients were administered a questionnaire regarding visual perceptions and satisfaction on performing daily activities following IOL implantation. The patients had to rate the occurrence of visual problems on a scale from 0 to 10, of which 0 referred to the complete absence of a problem and 10 corresponded to strong discomfort.
Statistical Analysis The statistical analysis was performed using SPSS software (version 21, SPSS, Inc.) and Medcalc software (version 12.3.0.0, Medcalc Software bvba). With Medcalc, the normality of the samples was tested using the Kolmogorov-Smirnov test. Because of a lack of a normal distribution of some variables, the medians with the interquartile ranges (75th quartile to 25th quartile) are shown. Furthermore, the detection of the statistical significance between paired samples of the binocular examination was performed using the Wilcoxon rank-sum test. These included the statistical comparison between the reading performance results at a fixed test distance and those in the respective preferred one as well as the comparison between the ETDRS visual acuity and the electronic reading desk reading acuity determined for the same distance. For the monocular examinations, the linear mixed model of SPSS software was used to test for statistical significance between the paired samples to take into consideration the correlations between each 2 eyes of the same patient. For both tests, the level of significance was a equal to 5%. The questionnaires were analyzed descriptively. Because this was an explorative study (to the authors’ knowledge, no other peer-reviewed publication had mentioned the examination of this specific IOL with the electronic reading
desk), all patients who met the inclusion criteria were included.
RESULTS Forty eyes of 20 patients with a mean age of 57.95 years G 8.55 (SD) were enrolled in the study. The IOL implantation was part of a RLE procedure in 32 eyes and part of cataract surgery in 8 eyes. Seven eyes had femtosecond laser–assisted surgery based on the patients’ wishes. The mean follow-up was 30.83 G 11.96 months postoperatively. One eye had an AL less than 22.0 mm, and 1 eye had an AL greater than 25.0 mm. Visual Acuity Despite theoretically offering only 2 foci and not offering an intermediate focus, the bifocal apodized diffractive IOL is expected to improve intermediate visual acuity results because its lower add of C3.0 D compared with previous IOL models with a C4.0 D add. Table 1 shows the monocular and binocular visual acuities. Reading Performance For technical reasons, the reading performance measurements at 80 cm could not be performed for 1 patient. Therefore for this distance, the number of patients was reduced to 19. Tables 2A, 2B, 3A, and 3B show the results of the different parameters measured during the monocular and the binocular electronic reading desk examinations with and without distance correction. The differences between the measurements at a fixed distance of 40 cm or 80 cm and the respective preferred distance were tested for statistical significance. The patient's preferred near and intermediate reading distances significantly differed from the respective predetermined ones in all cases.
Table 1. Visual acuity (ETDRS) in 40 eyes of 20 patients at far, intermediate, and near distances. Visual Acuity (LogMAR) Parameter Monocular Median IQR Min, Max Binocular Median IQR Min, Max
UDVA (4 m)
CDVA (4 m)
UIVA (80 cm)
DCIVA (80 cm)
UNVA (40 cm)
DCNVA (40 cm)
0.00 0.09 C0.26, 0.14
0.08 0.11 C0.16, 0.24
C0.15 0.21 C0.40, 0.18
C0.16 0.21 C0.42, 0.14
C0.04 0.13 C0.24, 0.10
0.00 0.12 C0.18, 0.22
0.06 0.13 C0.14, 0.20
0.13 0.09 0.02, 0.24
C0.01 0.15 C0.40, 0.20
C0.07 0.15 C0.26, 0.06
0.03 0.11 C0.08, 0.16
0.07 0.07 C0.08, 0.18
CDVA Z corrected distance visual acuity; DCIVA Z distance-corrected intermediate visual acuity; DCNVA Z distance-corrected near visual acuity; IQR Z interquartile range; UDVA Z uncorrected distance visual acuity; UIVA Z uncorrected intermediate visual acuity; UNVA Z uncorrected near visual acuity
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Table 2A. Median monocular intermediate distance reading performance with the electronic reading desk.*
Parameter Reading acuity (logMAR) Median IQR Smallest readable letter size (log-scaled) Median IQR Reading distance (cm) Median IQR Reading speed (wpm) Median IQR Reading duration (s) Median IQR
Uncorrected Intermediate (80 cm) (n Z 38)
Uncorrected Preferred Intermediate (n Z 40)
P Value
Distance-Corrected Intermediate (80 cm) (n Z 38)
Distance-Corrected Preferred Intermediate (n Z 40)
.079 0.30 0.13
.018
0.21 0.09
0.30 0.01
0.27 0.13
!.001 0.50 0.13
0.80 0.17
79.75 0.88
64.60 1.85
98.00 33.75
102.0 28.25
9.45 4.03
9.60 2.35
P Value
!.001 0.50 0.00
0.63 0.20
79.85 1.15
64.55 2.03
104.00 56.25
97.00 34.00
8.85 4.70
10.05 2.50
!.001
!.001
.579
.059
.488
.158
IQR Z interquartile range; wpm Z words per minute *Statistical differences were calculated for the monocular examination with the mixed model; level of significance: a Z 5%.
Visual Acuity With Early Treatment Diabetic Retinopathy Study Charts Versus Reading Acuity With the Electronic Reading Desk
electronic reading desk reading acuity measurements at the same distances (Table 4).
Binocular ETDRS uncorrected intermediate visual acuity (UIVA), distance-corrected intermediate visual acuity, uncorrected near visual acuity, and distance-corrected near visual acuity (DCNVA) (Table 1) were significantly better than the respective
Questionnaire All 20 patients completed the questionnaire. All patients filled out the questionnaire without glasses. Apart from driving at night, 80% or more of the patients were able to perform all activities without
Table 2B. Median binocular intermediate distance reading performance with the electronic reading desk.*
Parameter Reading acuity (logMAR) Median IQR Smallest readable letter size (log-scaled) Median IQR Reading distance (cm) Median IQR Reading speed (wpm) Median IQR Reading duration (s) Median IQR
Uncorrected Uncorrected Preferred Intermediate Intermediate (80 cm) (n Z 19) (n Z 20)
P Value
Distance-Corrected Distance-Corrected Intermediate Preferred Intermediate (80 cm) (n Z 19) (n Z 20)
.0728 0.18 0.20
.3247
0.19 0.13
0.18 0.13
0.19 0.07
!.0001 0.63 0.30
0.80 0.20
79.70 0.50
63.95 2.15
108.00 51.50
106.50 47.25
8.50 3.35
9.25 4.50
P Value
!.0001 0.63 0.13
0.80 0.09
79.60 1.25
63.90 2.83
109.00 55.00
107.00 52.00
9.00 3.70
9.25 4.20
!.0001
!.0001
.3321
.8288
.3247
.6794
IQR Z interquartile range; wpm Z words per minute *Statistical differences were calculated for the binocular examination with the Wilcoxon rank-sum test; level of significance: a Z 5%.
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Table 3A. Median monocular near distance reading performance with the electronic reading desk.*
Parameter Reading acuity (logMAR) Median IQR Smallest readable letter size (log-scaled) Median IQR Reading distance (cm) Median IQR Reading speed (wpm) Median IQR Reading duration (s) Median IQR
Uncorrected Near (80 cm) (n Z 40)
Uncorrected Preferred Near (n Z 40)
0.11 0.15
0.10 0.16
P Value
Distance-Corrected Near (80 cm) (n Z 40)
Distance-Corrected Preferred Near (n Z 40)
.002
.020 0.10 0.17
0.08 0.11
!.001 0.80 0.25
0.80 0.37
40.0 0.92
39.10 4.65
97.5 32.25
97.50 22.25
9.70 2.93
9.70 2.48
P Value
.001 0.80 0.37
1.0 0.20
39.90 0.62
39.65 3.15
105.00 43.00
92.50 40.75
9.75 3.55
10.50 3.63
.001
.001
.729
.057
.916
.027
IQR Z interquartile range; wpm Z words per minute *Statistical differences were calculated for the monocular examination with the mixed model; level of significance: a Z 5%.
spectacle correction (Figure 1). The most cited complaints were night glare (median rate 5.99) followed by halos (median rate 5.0), vision problems under low light conditions (median rate 3.75), and day glare (median rate 2.29) (Figure 2, A). The questionnaire also proved a high rate of spectacle independence for far, near, and intermediate
distance (Figure 2, B), with a larger range for the independence at near distance. DISCUSSION The increase in intermediate distance activities in everyday life led to an increased need for a
Table 3B. Median binocular near distance reading performance with the electronic reading desk.*
Parameter Reading acuity (logMAR) Median IQR Smallest readable letter size (log-scaled) Median IQR Reading distance (cm) Median IQR Reading speed (wpm) Median IQR Reading duration (s) Median IQR
Uncorrected Near (80 cm) (n Z 20)
Uncorrected Preferred Near (n Z 20)
P Value
Distance-Corrected Near (80 cm) (n Z 20)
Distance-Corrected Preferred Near (n Z 20)
.4648 0.05 0.13
0.03 0.09
.6875 0.01 0.09
0.01 0.050
.0156 0.90 0.24
1.00 0.20
39.95 1.33
39.45 7.43
120.5 41.25
115.50 58.25
8.60 3.18
8.70 3.45
.1250 1.00 0.20
1.00 0.00
40.15 0.67
39.60 3.72
120.00 65.25
120.50 43.00
8.30 4.70
8.20 2.63
.0068
.0469
.5771
.8125
.7002
1.000
IQR Z interquartile range; wpm Z words per minute *Statistical differences were calculated for the binocular examination with the Wilcoxon rank-sum test; level of significance: a Z 5%.
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P Value
READING PERFORMANCE USING AN ELECTRONIC READING DESK AFTER MULTIFOCAL IOL IMPLANTATION
Table 4. Visual acuity with ETDRS charts (Table 1) versus reading acuity with the electronic reading desk (Tables 2A, 2B, 3A, and 3B) at the same distances.* Parameter Intermediate distance (80 cm) Uncorrected monocular examination Distance-corrected monocular examination Uncorrected binocular examination Distance-corrected binocular examination Near distance (40 cm) Uncorrected monocular examination Distance-corrected monocular examination Uncorrected binocular examination Distance-corrected binocular examination
P Value !.001 !.001 .0008 .0004 !.001 .077 .0005 .0002
*Statistical differences were calculated for the monocular examination with the mixed model and for the binocular examination with the Wilcoxon rank-sum test. Level of significance: a Z 5%.
spectacle-independent intermediate vision. To meet the patients’ expectations, different multifocal IOL designs and surgical techniques have been developed, including bifocal IOLs with a low or moderate near add7 (eg, 2.5 D or 1.5 D) and trifocal IOLs that generate 3 foci. Furthermore, an improvement in intermediate vision can be achieved by monofocal IOLs using the micro-monovision technique, where for the dominant eye, emmetropia is targeted and for the nondominant eye, near or intermediate vision correction is targeted. Multifocal IOL optics with a moderate near add
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represent a good solution for not only generating 2 foci for far and near distances but also for improving vision at intermediate distances. The Acrysof IQ Restor multifocal C3.0 D SN6AD1 is considered an IOL with a moderate near add compared with its preceding design, the Acrysof IQ Restor C4.0 D SN6AD3 IOL. Good intermediate visual acuity results have been reported for the Acrysof IQ Restor multifocal C3.0 D SN6AD1 IOL.15–19 With the reduction in the near add from 4.0 D to 3.0 D, an improvement in intermediate visual acuity is sought. These adds correspond to 3.2 D and 2.4 D at the spectacle plane, respectively. Instead of a reading distance of 31 cm from the eye with the 4.0 D near add, a distance of 41 cm from the eye is targeted by the 3.0 D add. Wang et al.19 compared both IOLs and found a higher intermediate visual acuity at 60 cm and a higher 30 cm near visual acuity with the 3.0 D add IOL than with the 4.0 D add IOL. For evaluation of the visual and reading function in near and intermediate distance, we used 2 methods; namely, ETDRS charts and the Salzburg Reading Desk, an electronic reading desk. An advantage of the electronic reading desk is that it allows objective determination of the patients’ convenient near and intermediate distances. Moreover, reading complete sentences reflects the daily-life situation of reading texts on a computer screen or in a book. Furthermore, the electronic reading desk allows the performance of measurements under standardized conditions regarding screen
Figure 1. Questionnaire 1. Performance of various daily activities after bilateral implantation of the multifocal IOL (IOL Z intraocular lens; TV Z television).
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Figure 2. Questionnaire 2. A: Median scores of vision problems and perception of photic phenomena. B: Spectacle independence.
inclination, illumination, and contrast. For multifocal IOLs, the distribution of light energy on several foci would probably lead to impairment of the results under low light and contrast conditions when these settings are changed16; therefore, constant room illumination should also be noted. However, in this study, we focused on performing the examinations under standardized conditions to analyze the results at various distances with respect to the different parameters considered for calculating the reading acuity. This study was performed primarily to evaluate the Acrysof IQ Restor multifocal C3.0 D SN6AD1 IOL. The results of the examination at fixed distances of 40 cm and 80 cm can therefore not be applied to IOLs with other add powers and other apodized IOLs. It would be expected that an IOL with a near add of C4.0 D would result in lower visual acuity at 40 cm and at 80 cm. However, the examination at the preferred distances can be used to compare the preferred distance after the implantation of IOLs with various near adds. Ali o et al.20 published 6-month results and Rasp et al.6 published 12-month results of a comparison of different IOL models, including monofocal, diffractive multifocal,
and refractive multifocal IOLs, after their bilateral implantation. The studies found significantly better reading performance for the diffractive multifocal IOL than for monofocal and refractive multifocal IOLs. To our knowledge, this is the first peer-reviewed published study to examine patients with the Salzburg Reading Desk who had implantation of the Acrysof IQ Restor multifocal C3.0 D SN6AD1 IOL. The reading acuity measurements represent the major part of this study. The examination with the electronic reading desk resulted in medians of the preferred intermediate distance between 63.9 cm and 64.60 cm, whereas the medians of the preferred near distance ranged from 39.10 to 39.65 cm. At the preferred distances, either the same letter size could be read over a shorter duration or a smaller letter size could be read compared with the fixed test distance. However, in some cases an identical or even a lower reading acuity was measured at the preferred distance compared with the respective fixed one. This is caused by consideration of the reading distance for the calculation of the reading acuity. As a consequence, nearly identical reading acuity was achieved at the shorter preferred distances despite the smaller print size. The print size, however, significantly differed between the fixed and the preferred distances for all electronic reading desk examinations except for the binocular DCNVA examination. A limitation of the electronic reading desk could be seen in comparing examinations of a large number of patients, especially when performing the examinations in different languages, because the reading speed can vary individually and according to the speaking habit in different languages. In this study, all examinations were performed in German to ensure similar reading habits. A further limitation of the device is that it automatically shows sentences from a sentence database. If a sentence showed up twice, we repeated the measurements until a new sentence appeared to avoid memorization of the sentences. Only those measurements were saved and used for analysis in which a new sentence had appeared. This, however, causes the examination to be time consuming. Except for the distance-corrected monocular examination at 40 cm, significant differences were evident between all ETDRS results and the respective electronic reading desk reading acuity. The variations between the visual acuity and the reading acuity at the same distances can be explained by differences between reading sentences and reading ETDRS optotypes. When reading ETDRS letters, patients might skip a letter but still read the following ones. In the end, it is the number of correct letters that is evaluated. However, omitting a word when reading sentences is not possible because it slows the reading process,
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leading to a reduction in reading speed to values of less than 80 wpm. Sentences with less than 80 wpm were not considered in the results of this study because this is the threshold for healthy eyes.11,12,14 In a recent study Guo et al.,18 20 patients were examined after bilateral implantation of the SN6AD1 IOL. The examination of the preferred reading distance resulted in a value of 37.6 cm. On the bilateral defocus curve, a plateau was detected between the 2.0 D and the 2.5 D defocus with a visual acuity of more than 0.05 logMAR. This proves good visual acuity not only at the reading distance of 40 cm but also up to a distance of 50 cm from the eye. A similar plateau between 2.0 D and 2.5 D on the defocus curve was also found in several other studies examining the same IOL.16,17 Several studies have evaluated the intermediate distance results of the Acrysof IQ Restor multifocal C3.0 D SN6AD1 IOL. In a study by Lane et al.,17 the ETDRS results after bilateral implantation of the IOL showed a mean 60 cm UIVA of 0.17 G 0.14 logMAR. In another study by Alfonso et al.,15 the 6-month postoperative follow-up yielded UIVA results of 0.080 G 0.092 logMAR at 50 cm, 0.082 G 0.141 logMAR at 60 cm, and 0.165 G 0.111 logMAR at 70 cm. These results match our measurements of a smaller letter size read in the close intermediate distance rather than in the far intermediate distance. Similar values were found in a multicenter study by Kohnen et al.16 In that study, the mean preferred reading distance was 41.0 G 4.0 cm. Six months postoperatively, the binocular near and intermediate visual acuity in 10 cm increments showed a decreasing visual acuity between 40 cm and 70 cm. The lowest intermediate visual acuity was at the 70 cm distance and yielded a mean of 0.20 G 0.14 logMAR. Regarding the intermediate distance functional results of trifocal IOLs, results with the 3.0 D add IOL we studied seem to be comparable. Bilateral implantation of the Finevision IOL in 20 patients by Ali o et al.21 resulted in a mean monocular UIVA of 0.20 G 0.11 logMAR at 80 cm 6 months postoperatively with a visual acuity of 0.19 G 0.08 logMAR at the 1.5 D defocus of the binocular defocus curve. Mojzis et al.22 examined a cohort of 30 patients after the bilateral implantation of the AT Lisa tri 839 MP IOL for intermediate visual acuity in 66 cm. The mean UIVA was 0.08 G 0.10 logMAR. The different multifocal IOL designs have disadvantages; the generation of straylight by the refractive and diffractive ring structures leads to increased glare and halo perception.16 Moreover, the light distribution on 2 or even 3 distances could cause a decrease in contrast sensitivity or difficulty in vision, above all under dim light conditions.16 Therefore, the development of
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new IOL designs aims to ensure spectacle independence at all distances and also to reduce the associated photic phenomena and to keep the decrease in contrast sensitivity to a minimum. Several studies of the Acrysof IQ Restor multifocal C3.0 D SN6AD1 IOL reported photic phenomena and patient satisfaction outcomes similar to ours. Glare and halos were classified as mild16,18 to moderate15 in various studies. Nevertheless, the patients were satisfied and reported high spectacle independence.18,23 The high spectacle independence at far, computer, and near distances were reported in studies,16,24 similar to the results in our study. Furthermore, high satisfaction concerning the performance of daily activities at various distances has been reported.15,16 In conclusion, the Acrysof IQ Restor multifocal C3.0 D SN6AD1 IOL provided good functional results at far and near distances and improved visual and reading performance at the intermediate distance by the near add of C3.0 D. The evaluation of patient satisfaction reflected a high rate of spectacle independence, even at the intermediate distance, and a high rate of satisfaction while performing daily activities at various distances. Despite reported halos and glare, there was no limitation of daily activities, no IOL exchange was required, and 90% of the patients said they would have the surgery with the same IOL model again.
WHAT WAS KNOWN The multifocal C3.0 D add IOL improves near vision and supports intermediate vision by its moderate near add of 3.0 D. WHAT THIS PAPER ADDS The reading acuity measurement reflected the patient’s daily performance on reading texts instead of measuring the visual acuity using single optotypes. The determination of reading acuity up to a minimum reading speed of 80 wpm reflected patient satisfaction in everyday life as it is the lower threshold for recreational reading. The preferred near distance after bilateral implantation of the C3.0 D add IOL almost matched the fixed near distance of 40 cm. However, the preferred intermediate distance differed from the fixed intermediate distance of 80 cm. Reading was more convenient at distances between 60 cm and 70 cm. Patients reported a high rate of spectacle independence, even at intermediate distances.
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First author: Mary S.A. Attia, MD International Vision Correction Research Centre and David J. Apple Laboratory, University Eye Clinic, Heidelberg, Germany