Acta Ophthalmologica 2015
Short-term outcomes of combined implantation of diffractive multifocal intraocular lenses with different addition power Ken Hayashi, Motoaki Yoshida, Akira Hirata and Koichi Yoshimura Hayashi Eye Hospital, Fukuoka, Japan
ABSTRACT. Purpose: To compare short-term binocular visual function between patients implanted with diffractive multifocal intraocular lenses (MIOLs) of different near addition powers in each eye or the same MIOLs bilaterally. Methods: Seventy patients scheduled for implantation of diffractive MIOLs were divided into two groups: (i) mix and match group, a MIOL with +3.0 dioptre (D) addition power implanted in the dominant eye (Alcon SN60D1) and a MIOL with +4.0D power implanted in the non-dominant eye (SN60D3) or (ii) same MIOL group, same MIOL (SN60D1) implanted bilaterally. At 3 months postoperatively, we examined binocular visual acuity (VA) at various distances, binocular contrast VA and that with a glare (glare VA), and near stereoacuity. Results: Mean binocular uncorrected (UNVA) or corrected near VA (CNVA) at 0.3 m was significantly better in the mix and match group than in the same MIOL group (p ≤ 0.0066). Binocular uncorrected and distance-corrected VA at other distances was similar. Binocular UNVA of 0.8 or better was achieved in 77.1% of patients in the mix and match group and 45.7% in the same MIOL group (p = 0.0144). Binocular contrast and glare VA, and stereoacuity did not significantly differ between groups. Spectacle independence and patient satisfaction with near vision were significantly better in the mix and match group (p ≤ 0.0195). Conclusion: Mix and match implantation of diffractive MIOLs with different addition power provides a better binocular VA curve and spectacle independence than bilateral implantation of the same MIOLs, without compromising contrast sensitivity and stereopsis. Key words: binocular visual function – cataract surgery – diffractive multifocal intraocular lens – mix and match implantation – near addition power
Acta Ophthalmol. 2015: 93: e287–e293 ª 2014 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd
doi: 10.1111/aos.12591
Introduction Several types of refractive and diffractive multifocal intraocular lenses (MIOLs) with different structural designs, near addition power, or presence of apodization have been
developed (Kohnen et al. 2006; Souza et al. 2006; Hayashi et al. 2009a,b; Alfonso et al. 2010; Packer et al. 2010; Alio et al. 2012; Sheppard et al. 2013; Van der Linden et al. 2014). Each MIOL has advantages and disadvantages; thus, meeting patient
requirements with bilateral implantation of the same MIOL is difficult. Implantation of different types of MIOLs in each eye, referred to here as the ‘mix and match’ method, provides excellent binocular visual function by utilizing binocular summation (Goes 2008; Lacmanovic-Loncar et al. 2008; Lubi nski et al. 2011). Previous studies revealed that patients who underwent combined implantation of refractive and diffractive types of MIOLs had better near or intermediate visual acuity (VA) than patients who underwent bilateral implantation of monofocal IOLs or unilateral MIOL implantation (Gunec & Celik 2008; Chen et al. 2011; Yoon et al. 2013). Recent studies using a stricter study design also showed that combined implantation of refractive and diffractive MIOLs provided better near vision than bilateral implantation of the same refractive IOL (Buckhurst et al. 2012; Lin et al. 2012). No studies to date, however, have compared binocular visual function between patients who received different types of diffractive or refractive MIOLs in each eye and those who received the same types of diffractive or refractive MIOL in both eyes. The purpose of this study was to compare short-term binocular visual function between patients who underwent mix and match implantation of diffractive MIOLs with different near addition power and patients who underwent bilateral implantation of the same type of diffractive MIOL. To adequately assess binocular vision, we examined binocular uncorrected or
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corrected VA at various distances, binocular contrast sensitivity, stereoacuity, spectacle independence and patient satisfaction.
Patients and Methods Patients
This study was a prospective nonrandomized comparative study. The patients could not be randomized because the Japanese National Health Insurance does not cover the cost of MIOLs, and patients must therefore pay the cost themselves. Accordingly, patients who want to receive a MIOL have a right to choose the type of MIOL. All patients who elected to undergo bilateral implantation of MIOLs between July 2011 and June 2013 were screened by two clinical research co-ordinators. Exclusion criteria were patients with pathology of the cornea, macular or optic nerve; severe opaque media other than cataract; history of ocular inflammation or surgery; corneal astigmatism of more than 1.5 D; night-time driving difficulty; and any difficulties with examinations, analyses, or follow-up. The physician (K.H.) informed all patients who met the inclusion criteria of the characteristics of all of the types of MIOLs that are available in Japan. When the patients opted for bilateral implantation of a diffractive MIOL, they were further informed of the possible advantages and disadvantages of combined implantation of diffractive MIOLs with different near addition power or bilateral implantation of the same diffractive MIOLs. After expressing an understanding of the explanation, the patient selected the type of diffractive MIOLs that were to be implanted. Patients were divided into two groups: mix and match group, in which a MIOL with +3.0 dioptre (D) addition power implanted in the dominant eye (ReSTOR +3D, SN6AD1; Alcon Laboratories, Fort Worth, TX, USA) and a MIOL with +4.0D power was implanted in the non-dominant eye (ReSTOR +4D, SN6AD3; Alcon), or same MIOL group, in which the same MIOL (SN60D1; Alcon) was implanted bilaterally. Patient screening was continued until 35 patients were enrolled in each group. The Institutional Review Board of the Hayashi Eye Hospital approved the study
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protocol, and written informed consent was obtained from each patient. Multifocal intraocular lenses
The Alcon aspheric diffractive MIOL with +3D addition power (SN6AD1) and the diffractive MIOL with +4 D addition power (SN6AD3) are singlepiece hydrophobic acrylic IOLs with an apodized diffractive multifocal structure on the anterior optic surface. The apodized multifocal structure, located within the central 3.6 mm optic zone, comprises 9 or 12 concentric steps of decreasing height, thereby creating multifocality from distance to near. The refractive portion of the optic, which is used for distance vision, surrounds the diffractive region. The anterior surface of the optic is aspheric, and the optic material is yellow-tinted. The dominant eye was determined using a hole-in-card test (sighting dominance) in which the patients were asked to look at a Landolt target at 5 m through a 1 cm hole in the centre of the cardboard (Hayashi et al. 2010). The SN6AD1 was implanted in the dominant eye, while the SN6AD3 was implanted in the non-dominant eye. Surgical technique
All surgeries were performed by single surgeon (K.H.) using the previously described surgical procedures (Hayashi et al. 2009a,b). Cataract surgery on the second eye was performed at approximately 2 days after surgery on the first eye. For phacoemulsification, the surgeon made a 2.4-mm clear corneal incision horizontally for eyes with against-the-rule or oblique corneal astigmatism, and superiorly for eyes having with-the-rule astigmatism. After incision, a continuous curvilinear capsulorhexis measuring approximately 5.5 mm in diameter was created using a 25-gauge bent needle. After hydrodissection, endocapsular phacoemulsification of the nucleus and aspiration of the residual cortex were conducted. The lens capsule was inflated with 1% sodium hyaluronate (Healon; AMO, Santa Ana, CA, USA), after which the IOL was placed into the capsular bag using an Alcon Monarch II injector. After IOL insertion, the viscoelastic material was thoroughly evacuated. In this series, all surgeries were uneventful, and all IOLs were implanted in the capsular bag.
Outcome measures
At 3 months after surgery, all patients underwent examinations of monocular and binocular uncorrected or corrected distance VA at far to near distances, binocular contrast sensitivity with and without glare, near stereoacuity, refractive status, keratometric cylinder and pupillary diameter. The primary endpoint was binocular uncorrected VA from far to near distances measured using the all-distance vision tester (AS-15; Kowa, Nagoya, Japan). For both monocular and binocular VA, uncorrected and corrected VA from far to near distances was measured using the AS-15. The methods used to measure VA at the various distances using the AS-15 were described previously (Hayashi et al. 2009a,b). This device measures equivalent VA at infinity (∞), and at 5.0, 3.0, 2.0, 1.0, 0.7, 0.5 and 0.3 m distances by placing a spherical lens and variously sized visual targets at appropriate distances along the visual axis. For example, the VA at ∞ m is measured by placing a spherical lens (focal distance = 250 mm) at 250 mm from the patient’s eye and a visual target at 500 mm. We define VA at 0.7 and 0.5 m to be intermediate VA, and VA at 0.3 m to be near VA. After distance correction, binocular VA at high to low contrast levels (contrast VA) and that in the presence of a glare source (glare VA) under photopic and mesopic conditions were examined using the Contrast Sensitivity Accurate Tester (CAT-2000; Menicon, Nagoya, Japan) (Hayashi et al. 2009a). This device measures the logarithm of the minimal angle of resolution (logMAR) VA using five contrasts of visual targets (100%, 25%, 10%, 5% and 2.5%) under photopic and mesopic lighting conditions. The detection limit of the CAT-2000 is logMAR VA 1.0. Measurement under the photopic lighting condition was made with chart luminance of 100 candelas (cd)/ m2, while chart luminance under the mesopic condition was 2 cd/m2. A glare source of 200 lux was located in the periphery at 20° around the visual axis. Near stereoacuity with correction at 0.4 m was measured using the Titmus stereo test under photopic conditions (80–100 cd/m2). Measurement was taken without correction for near
Acta Ophthalmologica 2015
vision. Stereoacuity was determined by the number of circles answered correctly by the patients, and this number was converted to seconds of arc (arc sec) for statistical analysis. A stereoacuity level of circle 5, which is equivalent to 100 arc sec, was considered to be the lowest limit of useful stereoacuity (Isomura & Awaya 1980). The objective refractive status (spherical and cylindrical powers) and keratometric cylinder were measured using an autorefractometer (KR-7100; Topcon, Tokyo, Japan). The subjective refractive status was also examined. The manifest spherical equivalent value was determined as the spherical power plus half the cylindrical power. The pupillary diameter was examined using a Colvard pupillometer (Oasis Medical, Glendora, CA, USA). All examinations were performed by five experienced ophthalmic technicians unaware of the objective of the study. Spectacle dependency for distance and near vision, patient satisfaction for distance and near vision, and glare and halo symptoms were examined by administering a patient questionnaire. The patients were asked if they wore spectacles either for distance or near vision in daily life. If the response was yes, the patients were then asked if the spectacles were worn always, occasionally, or only when necessary. Overall patient satisfaction was classified according to the patient’s response; very satisfied, satisfied, not applicable or unsatisfied. Glare and halo symptoms were also classified according to the patient’s response; severe, moderate, slight and none.
male and female, and other categorical variables with two variables between two groups were compared using Fisher’s exact test or the chi-square test. Categorical variables with three or more variables were compared between groups using the goodness test of fit for chi-square. Any differences with a p-value 0.9999 >0.9999
the mix and match group than in patients in the same MIOL group, while that for distance vision was comparable. These results suggest that combined implantation of diffractive MIOLs with +3D and +4D addition power provided better near vision than did bilateral implantation of the same MIOLs with +3D power. Binocular contrast VA and glare VA under both photopic and mesopic conditions were almost the same between patients who underwent mix and match implantation of diffractive MIOLs and patients who underwent bilateral implantation of the same diffractive MIOL. In our previous studies, a decrease in contrast sensitivity was more prominent in patients with a diffractive MIOL with +4D addition power than a diffractive MIOL with +3D addition power (Hayashi et al. 2009a,b). These findings suggest that, when diffractive MIOLs with +3D and +4D addition power were implanted in each eye, respectively, the patients had binocular contrast sensitivity and glare disability comparable to those of patients who received the same MIOL with +3D addition power bilaterally. Mean near stereoacuity was virtually the same between the mix and match and same MIOL groups. In addition, the incidence of patients who achieved a disparity threshold of 100 arc sec or better and 40 arc sec or better was similar between the mix and match and same MIOL groups. Studies showed that near focal distance is approximately 40 cm in eyes with the diffractive MIOL with +3D addition power and 30 cm in eyes with the MIOL with +4D addition power (Maxwell et al. 2009; de Vries et al. 2010; Petermeier et al. 2011; Rabsilber et al. 2013). Thus, although the optimal distance for near vision was different between the left and right eyes, near stereoacuity was not compromised in patients who underwent mix and match implantation of the diffractive MIOLs. Previous studies showed that patients who underwent combined implantation of refractive and diffractive types of MIOL have better near or intermediate VA than patients who underwent bilateral implantation of monofocal IOLs or unilateral implantation of a MIOL (Gunec & Celik 2008; Chen et al. 2011; Yoon et al. 2013). More recent study described by Lin et al. (2012) revealed that
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Fig. 5. Comparison of spectacle dependency and patient satisfaction with distance and near vision between patients who underwent mix and match implantation of diffractive multifocal intraocular lenses (MIOLs) with +3D and +4D addition power (mix and match group) and patients who underwent bilateral implantation of the same diffractive MIOL with +3D addition power (same MIOL group). *Statistically significant difference between groups.
Table 3. Number (%) of patients who reported glare or halo symptoms.
Glare symptoms Severe Moderate Slight None Halo symptoms Severe Moderate Slight None
‘Mix and match’ group
Same MIOL group
p-Value
4 2 12 17
(11.4) (5.7) (34.3) (48.6)
3 3 6 23
(8.6) (8.6) (17.1) (65.7)
0.3557*
2 6 12 15
(5.7) (17.1) (34.3 (42.9)
2 6 10 17
(5.7) (17.1) (28.6) (48.6)
0.9587*
* The goodness test of fit for chi-square.
combined implantation of refractive and diffractive MIOLs provides better binocular near VA than bilateral implantation of the same refractive IOL. Buckhurst et al. (2012) reported that patients who underwent combined implantation of refractive and diffractive MIOLs have binocular near and intermediate vision comparable to that of patients who underwent bilateral implantation of the same refractive or diffractive MIOL. No studies to date, however, have examined binocular visual function with mix and match implantation of diffractive MIOLs. The present study demonstrated that patients who received the different diffractive MIOLs in each eye had a better vision curve than patients who received the same diffractive MIOLs in both eyes, without compromising
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intermediate and distance vision, contrast sensitivity and stereopsis. In addition, trifocal IOLs that have three focal points at far, near and intermediate distances were recently developed. However, although several studies showed that trifocal IOLs provide useful intermediate VA without compromising near and distance VA (Lesieur 2012; Mojzis et al. 2013; Sheppard et al. 2013), there is no study to date to compare binocular vision at far, near and intermediate distances between mix and match implantation of bifocal IOL with different near addition and bilateral implantation of a trifocal IOL. Alcon ReSTOR diffractive MIOLs have a distance-dominant multifocal structure, compared to the other diffractive MIOLs, including an apodized
diffractive structure or surrounding distance refractive zone. Specifically, because the ReSTOR +3D has a near addition power of +3D, which is equivalent to +2.25D at the spectacle plane, the near focal distance is approximately 40–45 cm with this MIOL. Previous studies did not find a significant difference in near VA between eyes with the ReSTOR +3D and those with the +4D, although intermediate VA is significantly better with the ReSTOR+3D than with the +4D (Maxwell et al. 2009; de Vries et al. 2010; Petermeier et al. 2011; Rabsilber et al. 2013). In our prior studies, however, we found that near VA at 0.3 m is significantly better in eyes with the ReSTOR +4D than in eyes with the +3D (Hayashi et al. 2009a,b). Based on these findings, we consider that binocular near vision may be insufficient for some patients when the ReSTOR +3D is implanted in both eyes. For better binocular near vision, combined implantation of ReSTOR +3D and +4D is a valuable option without compromising intermediate vision. The fact that the patients were not randomized to the two groups is a limitation of the present study. The reason for this is that Japanese National Health Insurance does not cover the costs of multifocal IOL and its surgery, and thus patients must choose which multifocal IOL is to be implanted in their eye. The patient characteristics did not differ significantly between the two groups, and thus we believe that patient enrolment did not bias the results of the present study. In conclusion, mix and match implantation of diffractive MIOL with +3D and +4D near addition power provides better near VA than bilateral implantation of the same MIOLs with +3D addition power, without compromising intermediate and distance VA. Additionally, spectacle dependency and patient satisfaction with near vision were also better in patients who underwent mix and match implantation. Furthermore, contrast sensitivity and stereoacuity in patients who underwent combined implantation of different MIOLs were comparable to those in patients who underwent bilateral implantation of the same MIOL. In the present study, however, although the effect of binocular summation with mix and match implantation was
Acta Ophthalmologica 2015
verified, only near addition power was different in the multifocal structure. Further studies are necessary to accurately assess binocular visual function when MIOLs with greater differences between them are implanted in each eye.
References Alfonso JF, Puchades C, Fernandez-Vega L, Merayo C & Montes-Mic o R (2010): Contrast sensitivity comparison between AcrySof ReSTOR and Acri.LISA aspheric intraocular lenses. J Cataract Refract Surg 26: 471–477. Alio JL, Plaza-Puche AB, Javaloy J, Ayala MJ, Moreno LJ & Pi~ nero DP (2012): Comparison of a new refractive multifocal intraocular lens with an inferior segmental near add and a diffractive multifocal intraocular lens. Ophthalmology 119: 555–563. Buckhurst P, Wolffsohn JS, Naroo SA, Davies LN, Bhogal GK, Kipioti A & Shah S (2012): Multifocal intraocular lens differentiation using defocus curves. Invest Ophthalmol Vis Sci 53: 3920–3926. Chen W, Meng Q, Ye H & Liu Y (2011): Reading ability and stereoacuity with combined implantation of refractive and diffractive intraocular lenses. Acta Ophthalmol 89: 376–381. Goes FJ (2008): Visual results following implantation of a refractive multifocal IOL in one eye and a diffractive multifocal IOL in the contralateral eye. J Refract Surg 24: 300–305. Gunec U & Celik L (2008): Long-term experience with mixing and matching refractive Array and diffractive CeeOn multifocal intraocular lenses. J Refract Surg 24: 233–242. Hayashi K, Manabe S & Hayashi H (2009a): Visual acuity from far to near and contrast sensitivity in eyes with a diffractive multifocal intraocular lens with a low addition power. J Cataract Refract Surg 35: 2070–2076. Hayashi K, Masumoto M & Hayashi H (2009b): All-distance visual acuity in eyes with a nontinted or a yellow-tinted diffractive multifocal intraocular lens. Jpn J Ophthalmol 53: 100–106. Hayashi K, Yoshida M, Manabe S & Hayashi H (2010): Optimal target anisometropia for
pseudophakic monovision. J Refract Surg 27: 332–338. Isomura Y & Awaya S (1980): Studies on aniseikonia and binocular fusion with special reference to stereoacuity. J Jpn Ophthalmol Soc 84: 1619–1628. Kohnen T, Allen D, Boureau C, Dublineau P, Hartmann C, Mehdorn E, Rozot P & Tassinari G (2006): European multicenter study of the AcrySof ReSTOR apodized diffractive intraocular lens. Ophthalmology 113: 578–584. Lacmanovic-Loncar V, Pavicic-Astalos J, Petric-Vikovic I & Mandic Z (2008): Multifocal intraocular “mix and match” lenses. Acta Clin Croat 47: 217–220. Lesieur G (2012): Outcomes after implantation of a trifocal diffractive IOL. J Fr Ophtalmol 35: 338–342. Lin HT, Chen WR, Ding ZF, Chen W & Wu CR (2012): Clinical evaluation of two multifocal intraocular lens implantation patterns. Int J Ophthalmol 5: 76–83. Lubi nski W, Podboraz czy nska-Jodko K, Gronkowska-Serafin J & Karczewicz D (2011): Visual outcomes three and six months after implantation of diffractive and refractive multifocal IOL combinations. Klin Oczna 113: 209–215. Maxwell WA, Cionni RJ, Lehmann RP & Modi SS (2009): Functional outcomes after bilateral implantation of apodized diffractive aspheric acrylic intraocular lenses with a +3.0 or +4.0 diopter addition power: randomized multicenter clinical study. J Cataract Refract Surg 35: 2054–2061. Mojzis P, Pe~ na-Garcıa P, Liehneova I, Ziak P & Ali o JL (2013): Outcomes of a new diffractive trifocal intraocular lens. J Cataract Refract Surg 40: 60–69. Packer M, Chu YR, Waltz KL et al. (2010): Evaluation of the aspheric tecnis multifocal intraocular lens: one-year results from the first cohort of the food and drug administration clinical trial. Am J Ophthalmol 149: 577–584. Petermeier K, Messias A, Gekeler F & Szurman P (2011): Effect of +3.00 diopter and 4.00 diopter additions in multifocal intraocular lenses on defocus profiles, patient satisfaction, and contrast sensitivity. J Cataract Refract Surg 37: 720–726. Rabsilber TM, Rudalevicius P, Jasinskas V, Holzer MP & Auffarth GU (2013): Influence of +3.00 D and +4.00 D near addition on
functional outcomes of a refractive multifocal intraocular lens model. J Cataract Refract Surg 39: 350–357. Sheppard AL, Shah S, Bhatt U, Bhogal G & Wolffsohn JS (2013): Visual outcomes and subjective experience after bilateral implantation of a new diffractive trifocal intraocular lens. J Cataract Refract Surg 39: 343–349. Souza CE, Muccioli C, Soriano ES et al. (2006): Visual performance of AcrySof ReSTOR apodized diffractive IOL: a prospective comparative trial. Am J Ophthalmol 141: 827–832. Van der Linden JW, Vrijman V, El-Saady R, van der Meulen IJ, Mourits MP & LapidGortzak R (2014): Autorefraction versus subjective refraction in a radially asymmetric multifocal intraocular lens. Acta Ophthalmol. [Epub ahead of print]. de Vries NE, Webers CAB, Mones-Mic o R, Ferrer-Blasco T & Nuijts RM (2010): Visual outcomes after cataract surgery with implantation of a +3.00 D or +4.00 D aspheric diffractive multifocal intraocular lens: comparative study. J Cataract Refract Surg 36: 1316–1322. Yoon SY, Song IS, Kim JY, Kim MJ & Tchah H (2013): Bilateral mix-and-match versus unilateral multifocal intraocular lens implantation: long-term comparison. J Cataract Refract Surg 39: 1682–1690.
Received on July 3rd, 2014. Accepted on October 6th, 2014. Correspondence: Ken Hayashi, MD Hayashi Eye Hospital 4-23-35, Hakataekimae Hakata-Ku Fukuoka 812-0011 Japan Tel: 81 92 431 1680 Fax: 81 92 441 5303 Email: [email protected] KH is responsible for the study conception and design; MY, AH, KY are responsible for data acquisition, KH is responsible for statistical analysis and interpretation of the data; KH is responsible for drafting and reviewing the article; MY, AH, KY did the final approval for the manuscript.
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Short-term outcomes of combined implantation of diffractive multifocal intraocular lenses with different addition power Ken Hayashi, Motoaki Yoshida, Akira Hirata and Koichi Yoshimura Hayashi Eye Hospital, Fukuoka, Japan
ABSTRACT. Purpose: To compare short-term binocular visual function between patients implanted with diffractive multifocal intraocular lenses (MIOLs) of different near addition powers in each eye or the same MIOLs bilaterally. Methods: Seventy patients scheduled for implantation of diffractive MIOLs were divided into two groups: (i) mix and match group, a MIOL with +3.0 dioptre (D) addition power implanted in the dominant eye (Alcon SN60D1) and a MIOL with +4.0D power implanted in the non-dominant eye (SN60D3) or (ii) same MIOL group, same MIOL (SN60D1) implanted bilaterally. At 3 months postoperatively, we examined binocular visual acuity (VA) at various distances, binocular contrast VA and that with a glare (glare VA), and near stereoacuity. Results: Mean binocular uncorrected (UNVA) or corrected near VA (CNVA) at 0.3 m was significantly better in the mix and match group than in the same MIOL group (p ≤ 0.0066). Binocular uncorrected and distance-corrected VA at other distances was similar. Binocular UNVA of 0.8 or better was achieved in 77.1% of patients in the mix and match group and 45.7% in the same MIOL group (p = 0.0144). Binocular contrast and glare VA, and stereoacuity did not significantly differ between groups. Spectacle independence and patient satisfaction with near vision were significantly better in the mix and match group (p ≤ 0.0195). Conclusion: Mix and match implantation of diffractive MIOLs with different addition power provides a better binocular VA curve and spectacle independence than bilateral implantation of the same MIOLs, without compromising contrast sensitivity and stereopsis. Key words: binocular visual function – cataract surgery – diffractive multifocal intraocular lens – mix and match implantation – near addition power
Acta Ophthalmol. 2015: 93: e287–e293 ª 2014 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd
doi: 10.1111/aos.12591
Introduction Several types of refractive and diffractive multifocal intraocular lenses (MIOLs) with different structural designs, near addition power, or presence of apodization have been
developed (Kohnen et al. 2006; Souza et al. 2006; Hayashi et al. 2009a,b; Alfonso et al. 2010; Packer et al. 2010; Alio et al. 2012; Sheppard et al. 2013; Van der Linden et al. 2014). Each MIOL has advantages and disadvantages; thus, meeting patient
requirements with bilateral implantation of the same MIOL is difficult. Implantation of different types of MIOLs in each eye, referred to here as the ‘mix and match’ method, provides excellent binocular visual function by utilizing binocular summation (Goes 2008; Lacmanovic-Loncar et al. 2008; Lubi nski et al. 2011). Previous studies revealed that patients who underwent combined implantation of refractive and diffractive types of MIOLs had better near or intermediate visual acuity (VA) than patients who underwent bilateral implantation of monofocal IOLs or unilateral MIOL implantation (Gunec & Celik 2008; Chen et al. 2011; Yoon et al. 2013). Recent studies using a stricter study design also showed that combined implantation of refractive and diffractive MIOLs provided better near vision than bilateral implantation of the same refractive IOL (Buckhurst et al. 2012; Lin et al. 2012). No studies to date, however, have compared binocular visual function between patients who received different types of diffractive or refractive MIOLs in each eye and those who received the same types of diffractive or refractive MIOL in both eyes. The purpose of this study was to compare short-term binocular visual function between patients who underwent mix and match implantation of diffractive MIOLs with different near addition power and patients who underwent bilateral implantation of the same type of diffractive MIOL. To adequately assess binocular vision, we examined binocular uncorrected or
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corrected VA at various distances, binocular contrast sensitivity, stereoacuity, spectacle independence and patient satisfaction.
Patients and Methods Patients
This study was a prospective nonrandomized comparative study. The patients could not be randomized because the Japanese National Health Insurance does not cover the cost of MIOLs, and patients must therefore pay the cost themselves. Accordingly, patients who want to receive a MIOL have a right to choose the type of MIOL. All patients who elected to undergo bilateral implantation of MIOLs between July 2011 and June 2013 were screened by two clinical research co-ordinators. Exclusion criteria were patients with pathology of the cornea, macular or optic nerve; severe opaque media other than cataract; history of ocular inflammation or surgery; corneal astigmatism of more than 1.5 D; night-time driving difficulty; and any difficulties with examinations, analyses, or follow-up. The physician (K.H.) informed all patients who met the inclusion criteria of the characteristics of all of the types of MIOLs that are available in Japan. When the patients opted for bilateral implantation of a diffractive MIOL, they were further informed of the possible advantages and disadvantages of combined implantation of diffractive MIOLs with different near addition power or bilateral implantation of the same diffractive MIOLs. After expressing an understanding of the explanation, the patient selected the type of diffractive MIOLs that were to be implanted. Patients were divided into two groups: mix and match group, in which a MIOL with +3.0 dioptre (D) addition power implanted in the dominant eye (ReSTOR +3D, SN6AD1; Alcon Laboratories, Fort Worth, TX, USA) and a MIOL with +4.0D power was implanted in the non-dominant eye (ReSTOR +4D, SN6AD3; Alcon), or same MIOL group, in which the same MIOL (SN60D1; Alcon) was implanted bilaterally. Patient screening was continued until 35 patients were enrolled in each group. The Institutional Review Board of the Hayashi Eye Hospital approved the study
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protocol, and written informed consent was obtained from each patient. Multifocal intraocular lenses
The Alcon aspheric diffractive MIOL with +3D addition power (SN6AD1) and the diffractive MIOL with +4 D addition power (SN6AD3) are singlepiece hydrophobic acrylic IOLs with an apodized diffractive multifocal structure on the anterior optic surface. The apodized multifocal structure, located within the central 3.6 mm optic zone, comprises 9 or 12 concentric steps of decreasing height, thereby creating multifocality from distance to near. The refractive portion of the optic, which is used for distance vision, surrounds the diffractive region. The anterior surface of the optic is aspheric, and the optic material is yellow-tinted. The dominant eye was determined using a hole-in-card test (sighting dominance) in which the patients were asked to look at a Landolt target at 5 m through a 1 cm hole in the centre of the cardboard (Hayashi et al. 2010). The SN6AD1 was implanted in the dominant eye, while the SN6AD3 was implanted in the non-dominant eye. Surgical technique
All surgeries were performed by single surgeon (K.H.) using the previously described surgical procedures (Hayashi et al. 2009a,b). Cataract surgery on the second eye was performed at approximately 2 days after surgery on the first eye. For phacoemulsification, the surgeon made a 2.4-mm clear corneal incision horizontally for eyes with against-the-rule or oblique corneal astigmatism, and superiorly for eyes having with-the-rule astigmatism. After incision, a continuous curvilinear capsulorhexis measuring approximately 5.5 mm in diameter was created using a 25-gauge bent needle. After hydrodissection, endocapsular phacoemulsification of the nucleus and aspiration of the residual cortex were conducted. The lens capsule was inflated with 1% sodium hyaluronate (Healon; AMO, Santa Ana, CA, USA), after which the IOL was placed into the capsular bag using an Alcon Monarch II injector. After IOL insertion, the viscoelastic material was thoroughly evacuated. In this series, all surgeries were uneventful, and all IOLs were implanted in the capsular bag.
Outcome measures
At 3 months after surgery, all patients underwent examinations of monocular and binocular uncorrected or corrected distance VA at far to near distances, binocular contrast sensitivity with and without glare, near stereoacuity, refractive status, keratometric cylinder and pupillary diameter. The primary endpoint was binocular uncorrected VA from far to near distances measured using the all-distance vision tester (AS-15; Kowa, Nagoya, Japan). For both monocular and binocular VA, uncorrected and corrected VA from far to near distances was measured using the AS-15. The methods used to measure VA at the various distances using the AS-15 were described previously (Hayashi et al. 2009a,b). This device measures equivalent VA at infinity (∞), and at 5.0, 3.0, 2.0, 1.0, 0.7, 0.5 and 0.3 m distances by placing a spherical lens and variously sized visual targets at appropriate distances along the visual axis. For example, the VA at ∞ m is measured by placing a spherical lens (focal distance = 250 mm) at 250 mm from the patient’s eye and a visual target at 500 mm. We define VA at 0.7 and 0.5 m to be intermediate VA, and VA at 0.3 m to be near VA. After distance correction, binocular VA at high to low contrast levels (contrast VA) and that in the presence of a glare source (glare VA) under photopic and mesopic conditions were examined using the Contrast Sensitivity Accurate Tester (CAT-2000; Menicon, Nagoya, Japan) (Hayashi et al. 2009a). This device measures the logarithm of the minimal angle of resolution (logMAR) VA using five contrasts of visual targets (100%, 25%, 10%, 5% and 2.5%) under photopic and mesopic lighting conditions. The detection limit of the CAT-2000 is logMAR VA 1.0. Measurement under the photopic lighting condition was made with chart luminance of 100 candelas (cd)/ m2, while chart luminance under the mesopic condition was 2 cd/m2. A glare source of 200 lux was located in the periphery at 20° around the visual axis. Near stereoacuity with correction at 0.4 m was measured using the Titmus stereo test under photopic conditions (80–100 cd/m2). Measurement was taken without correction for near
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vision. Stereoacuity was determined by the number of circles answered correctly by the patients, and this number was converted to seconds of arc (arc sec) for statistical analysis. A stereoacuity level of circle 5, which is equivalent to 100 arc sec, was considered to be the lowest limit of useful stereoacuity (Isomura & Awaya 1980). The objective refractive status (spherical and cylindrical powers) and keratometric cylinder were measured using an autorefractometer (KR-7100; Topcon, Tokyo, Japan). The subjective refractive status was also examined. The manifest spherical equivalent value was determined as the spherical power plus half the cylindrical power. The pupillary diameter was examined using a Colvard pupillometer (Oasis Medical, Glendora, CA, USA). All examinations were performed by five experienced ophthalmic technicians unaware of the objective of the study. Spectacle dependency for distance and near vision, patient satisfaction for distance and near vision, and glare and halo symptoms were examined by administering a patient questionnaire. The patients were asked if they wore spectacles either for distance or near vision in daily life. If the response was yes, the patients were then asked if the spectacles were worn always, occasionally, or only when necessary. Overall patient satisfaction was classified according to the patient’s response; very satisfied, satisfied, not applicable or unsatisfied. Glare and halo symptoms were also classified according to the patient’s response; severe, moderate, slight and none.
male and female, and other categorical variables with two variables between two groups were compared using Fisher’s exact test or the chi-square test. Categorical variables with three or more variables were compared between groups using the goodness test of fit for chi-square. Any differences with a p-value 0.9999 >0.9999
the mix and match group than in patients in the same MIOL group, while that for distance vision was comparable. These results suggest that combined implantation of diffractive MIOLs with +3D and +4D addition power provided better near vision than did bilateral implantation of the same MIOLs with +3D power. Binocular contrast VA and glare VA under both photopic and mesopic conditions were almost the same between patients who underwent mix and match implantation of diffractive MIOLs and patients who underwent bilateral implantation of the same diffractive MIOL. In our previous studies, a decrease in contrast sensitivity was more prominent in patients with a diffractive MIOL with +4D addition power than a diffractive MIOL with +3D addition power (Hayashi et al. 2009a,b). These findings suggest that, when diffractive MIOLs with +3D and +4D addition power were implanted in each eye, respectively, the patients had binocular contrast sensitivity and glare disability comparable to those of patients who received the same MIOL with +3D addition power bilaterally. Mean near stereoacuity was virtually the same between the mix and match and same MIOL groups. In addition, the incidence of patients who achieved a disparity threshold of 100 arc sec or better and 40 arc sec or better was similar between the mix and match and same MIOL groups. Studies showed that near focal distance is approximately 40 cm in eyes with the diffractive MIOL with +3D addition power and 30 cm in eyes with the MIOL with +4D addition power (Maxwell et al. 2009; de Vries et al. 2010; Petermeier et al. 2011; Rabsilber et al. 2013). Thus, although the optimal distance for near vision was different between the left and right eyes, near stereoacuity was not compromised in patients who underwent mix and match implantation of the diffractive MIOLs. Previous studies showed that patients who underwent combined implantation of refractive and diffractive types of MIOL have better near or intermediate VA than patients who underwent bilateral implantation of monofocal IOLs or unilateral implantation of a MIOL (Gunec & Celik 2008; Chen et al. 2011; Yoon et al. 2013). More recent study described by Lin et al. (2012) revealed that
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Fig. 5. Comparison of spectacle dependency and patient satisfaction with distance and near vision between patients who underwent mix and match implantation of diffractive multifocal intraocular lenses (MIOLs) with +3D and +4D addition power (mix and match group) and patients who underwent bilateral implantation of the same diffractive MIOL with +3D addition power (same MIOL group). *Statistically significant difference between groups.
Table 3. Number (%) of patients who reported glare or halo symptoms.
Glare symptoms Severe Moderate Slight None Halo symptoms Severe Moderate Slight None
‘Mix and match’ group
Same MIOL group
p-Value
4 2 12 17
(11.4) (5.7) (34.3) (48.6)
3 3 6 23
(8.6) (8.6) (17.1) (65.7)
0.3557*
2 6 12 15
(5.7) (17.1) (34.3 (42.9)
2 6 10 17
(5.7) (17.1) (28.6) (48.6)
0.9587*
* The goodness test of fit for chi-square.
combined implantation of refractive and diffractive MIOLs provides better binocular near VA than bilateral implantation of the same refractive IOL. Buckhurst et al. (2012) reported that patients who underwent combined implantation of refractive and diffractive MIOLs have binocular near and intermediate vision comparable to that of patients who underwent bilateral implantation of the same refractive or diffractive MIOL. No studies to date, however, have examined binocular visual function with mix and match implantation of diffractive MIOLs. The present study demonstrated that patients who received the different diffractive MIOLs in each eye had a better vision curve than patients who received the same diffractive MIOLs in both eyes, without compromising
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intermediate and distance vision, contrast sensitivity and stereopsis. In addition, trifocal IOLs that have three focal points at far, near and intermediate distances were recently developed. However, although several studies showed that trifocal IOLs provide useful intermediate VA without compromising near and distance VA (Lesieur 2012; Mojzis et al. 2013; Sheppard et al. 2013), there is no study to date to compare binocular vision at far, near and intermediate distances between mix and match implantation of bifocal IOL with different near addition and bilateral implantation of a trifocal IOL. Alcon ReSTOR diffractive MIOLs have a distance-dominant multifocal structure, compared to the other diffractive MIOLs, including an apodized
diffractive structure or surrounding distance refractive zone. Specifically, because the ReSTOR +3D has a near addition power of +3D, which is equivalent to +2.25D at the spectacle plane, the near focal distance is approximately 40–45 cm with this MIOL. Previous studies did not find a significant difference in near VA between eyes with the ReSTOR +3D and those with the +4D, although intermediate VA is significantly better with the ReSTOR+3D than with the +4D (Maxwell et al. 2009; de Vries et al. 2010; Petermeier et al. 2011; Rabsilber et al. 2013). In our prior studies, however, we found that near VA at 0.3 m is significantly better in eyes with the ReSTOR +4D than in eyes with the +3D (Hayashi et al. 2009a,b). Based on these findings, we consider that binocular near vision may be insufficient for some patients when the ReSTOR +3D is implanted in both eyes. For better binocular near vision, combined implantation of ReSTOR +3D and +4D is a valuable option without compromising intermediate vision. The fact that the patients were not randomized to the two groups is a limitation of the present study. The reason for this is that Japanese National Health Insurance does not cover the costs of multifocal IOL and its surgery, and thus patients must choose which multifocal IOL is to be implanted in their eye. The patient characteristics did not differ significantly between the two groups, and thus we believe that patient enrolment did not bias the results of the present study. In conclusion, mix and match implantation of diffractive MIOL with +3D and +4D near addition power provides better near VA than bilateral implantation of the same MIOLs with +3D addition power, without compromising intermediate and distance VA. Additionally, spectacle dependency and patient satisfaction with near vision were also better in patients who underwent mix and match implantation. Furthermore, contrast sensitivity and stereoacuity in patients who underwent combined implantation of different MIOLs were comparable to those in patients who underwent bilateral implantation of the same MIOL. In the present study, however, although the effect of binocular summation with mix and match implantation was
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verified, only near addition power was different in the multifocal structure. Further studies are necessary to accurately assess binocular visual function when MIOLs with greater differences between them are implanted in each eye.
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Received on July 3rd, 2014. Accepted on October 6th, 2014. Correspondence: Ken Hayashi, MD Hayashi Eye Hospital 4-23-35, Hakataekimae Hakata-Ku Fukuoka 812-0011 Japan Tel: 81 92 431 1680 Fax: 81 92 441 5303 Email: [email protected] KH is responsible for the study conception and design; MY, AH, KY are responsible for data acquisition, KH is responsible for statistical analysis and interpretation of the data; KH is responsible for drafting and reviewing the article; MY, AH, KY did the final approval for the manuscript.
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