Visual Results Following Implantation of a Refractive Multifocal Intraocular Lens in One Eye and a Diffractive in the Contralateral Eye

Revan Yıldırım Karabağ; Üzeyir Günenç; Rukiye Aydın; Gül Arıkan; Hüseyin Aslankara

doi:10.4274/tjo.56588

ABSTRACT

Objectives

To assess the visual outcomes in patients who underwent cataract surgery with multifocal intraocular lens (IOL) implantation using a “mix and match” approach.

Materials and Methods

Twenty patients (40 eyes) were involved in this prospective, nonrandomized study. Refractive multifocal IOLs (ReZoom NXG1) were implanted in patients’ dominant eyes and diffractive multifocal IOLs (Tecnis ZMA00) were implanted in their non-dominant eyes. Monocular and binocular uncorrected distance, intermediate and near visual acuity (logMAR), and contrast sensitivity levels were measured at 1, 3, and 6 months after cataract surgery. Defocus curves, reading speeds, patient satisfaction, spectacle dependence, and halo and glare symptoms were also evaluated at 6 months after the surgery. Postoperative quality of life was assessed with the Turkish version of National Eye Institute Visual Function Questionnaire-25.

Results

The study group comprised 8 females and 12 males with a mean age of 69.45±10.76 years (range, 31-86 years). The uncorrected distance and intermediate visual acuity levels were significantly better in the ReZoom-implanted eyes at postoperative 6 months (p=0.026 and p=0.037, respectively). There was no statistically significant difference in uncorrected near visual acuity (p>0.05). There was no statistically significant difference in contrast sensitivity, reading speed, halos, or glare between the groups (p<0.05). Mild glare/halo was reported by 40% of the subjects. The mean patient satisfaction was 95% and all patients were spectacle independent.

Conclusion

Mixing and matching multifocal IOLs in selected cataract patients provides excellent visual outcome, a high level of patient satisfaction, and spectacle independency.

Keywords:

Mix and match, multifocal intraocular lenses, cataract

Introduction

Presbyopia is still one of the most challenging optical problems in cataract and refractive surgery, and spectacle independence is one of the major demands of the patients. Various presbyopic intraocular lenses (IOL) have been implanted to treat presbyopia during cataract surgery.^1,2,3

Multifocal IOLs have good clinical results with careful patient selection.^4,5,6,7 Clinically, there are two types of multifocal optics in IOLs: diffractive and refractive. Refractive multifocal IOLs provide very good visual results for intermediate and distance vision, but offer limited near vision.^8,9,10,11,12 Diffractive multifocal IOLs provide very good results at near vision, but may not function effectively at intermediate distances.^{8,9,10,11,12,13,14}

The ReZoom NXG1 multifocal IOL (Abbott Medical Optics, Santa Ana, CA, USA) is a three-piece, refractive, hydrophobic acrylic, aspheric IOL with UV blocking and an OptiEdge design that is claimed to minimize edge glare and reduce posterior capsular opacification. The refractive surface has 5 optical zones (zones 1, 3, and 5 are distance-dominant, whereas zones 2 and 4 are near-dominant). An aspheric transition between the zones is designed to provide balanced intermediate vision. It is designed to allow 100% light transmission in order to provide the full range of vision.¹⁵

The Tecnis ZMA00 multifocal IOL (Abbott Medical Optics, Santa Ana, CA, US) is a three-piece foldable, diffractive, aspheric, UV-blocking, hydrophobic acrylic optic with OptiEdge design. The modified, prolate anterior surface is designed to reduce spherical aberrations. The diffractive zones are located on the posterior surface. The diffractive pattern is 32 concentric circles with a +4 diopters (D) near addition that evenly splits the light entering the eye into two focal planes regardless of pupil size: one for distance and one for near.¹⁶

As with all multifocal IOL technologies, each of these unique designs has its limitations. With the aim of increasing patient satisfaction and spectacle independence after cataract surgery, a “mix and match” method involving implantation of a refractive multifocal IOL in one eye and a diffractive multifocal IOL in the contralateral eye, was first described by Gunenc in 2000. Preliminary findings with this approach were published in 2004 and long-term results in 2008.^17,18 The aim of this method is to extend depth of focus and quality of vision as well as decrease photic symptoms, increase spectacle independence rates, and improve distance, intermediate, and near visual acuity.

In this study, we evaluated visual results and patient satisfaction after using a “mix and match” approach of implanting new-generation refractive multifocal

Materials and Methods

Forty eyes of 20 patients (8 females and 12 males) who were examined at our clinic and had bilateral cataract were prospectively enrolled in this study. Using the “mix and match” approach, all patients received the ReZoom NXG1 refractive multifocal IOL in their dominant eye, followed by implantation of the Tecnis ZMA00 diffractive multifocal IOL in their nondominant eye two weeks later. The dominant eye was determined via a pinhole test. All patients were adequately informed and signed an informed consent form. The study was performed in accordance with the Declaration of Helsinki and was approved by the Dokuz Eylül University local ethics committee.

Bilateral cataract patients who did not want to wear glasses or contact lenses after surgery and had realistic expectations were included the study. The exclusion criteria were previous ocular surgery, ocular disease other than cataract, corneal astigmatism greater than 1.00 D, axial length (AL) less than 21.0 mm or more than 26.0 mm, myopia and hypermetropia greater than 5.00 D, pupil width less than 3 mm under dim light, and intraoperative complications.

Intraocular lens power calculation was made by using each patient’s keratometry, AL, and the A-constant of the IOL using both A-scan ultrasound (A-scan Nidek 3000, NIDEK Co., Japan) and laser interference biometry (the IOLMaster Version V2.02, Carl Zeiss Meditec AG, Germany). Biometry was done by the same doctor (R.Y.K.). Targeted refraction was emmetropia in all eyes. After considering both measurements and each patient’s AL, keratometric values, and anterior chamber depth, the SRK-T formula was used to determine the power of multifocal IOL to be implanted.

Results

The study group consisted of 40 eyes of 20 patients, including 8 females (40%) and 12 males (60%). The mean age of the patients was 69.45±10.76 years (range, 31-86 years). The mean preoperative corrected distance visual acuity (CDVA) was 0.33±0.22 logMAR.

Discussion

Several surgical techniques have been developed for the correction of pseudophakic presbyopia, including monovision,^21,22 multifocal IOLs,⁶ accomodative IOLs,²³ toric multifocal IOLs,²⁴ and trifocal IOLs.²⁵ The concept of mixing and matching refractive and diffractive multifocal IOLs was first described by Gunenc and Celik.^17,18 It is known that refractive multifocal IOLs provide good UDVA and UIVA,^26,27 while diffractive multifocal IOLs provide good UDVA and UNVA.^27,28,29,30 Mixing and matching different IOLs could allow the surgeon to combine the advantages of both refractive and diffractive lens designs.

In Gunenc’s initial study,¹⁸ 10 patients received the diffractive multifocal IOL (811E CeeOn-diffractive group) in 1 eye, another 10 patients received the refractive multifocal IOL (Array SA40N-refractive group) in 1 eye, and the other 10 patients underwent bilateral implantation with the refractive multifocal IOL in one eye and diffractive multifocal IOL in the other eye (“mix and match” group). The results demonstrated that 100% of the patients in the “mix and match” group, 90% of the patients in the refractive group, and 80% of the patients in the diffractive group had UDVA of 20/25 or better. In addition, 90% of the patients from the “mix and match” group were able to live without spectacles, compared to 60% in the other groups. All patients were satisfied with their visual functions over long-term follow-up.

Currently available second-generation multifocal IOLs have overcome some of the drawbacks of the first-generation models. The results of the “mix and match” approach have been reported in a number of studies. Goes,³¹ Hütz et al.,³² and Lubiński et al.³³ reported the results of 20 patients who received ReZoom in their dominant eye and Tecnis ZM900 in their nondominant eye. Similarly, in the current study 20 patients received ReZoom in their dominant eye, but hydrophobic acrylic Tecnis ZMA00 in their nondominant eye (Table 5). In all four of these studies, patients’ binocular UDVA, UIVA, and UNVA were within satisfactory levels and levels of spectacle independence were quite high.

In the current study, UDVA in the ReZoom-implanted eyes was significantly better than in the Tecnis-implanted eyes. At 6 months after implantation, UDVA was 0.1 logMAR or better in the 95% of the ReZoom-implanted eyes versus 70% of the Tecnis ZMA00-implanted eyes. Binocular UDVA was 0.1 logMAR or better in all of the patients (20/20). Hütz et al.³² reported UDVA of 0.1 logMAR or better in the 80% of the ReZoom-implanted eyes but only 20% of the Tecnis ZM900-implanted eyes at postoperative 3 months. Binocular UDVA was 0.1 logMAR or better in 85% of the patients. In both studies, monocular UDVA results in the ReZoom-implanted eyes were significantly better than in the Tecnis-implanted eyes. In this study, 65% of the ReZoom-implanted eyes achieved an UIVA of 0.1 logMAR or better, compared with 30% of the Tecnis ZMA00-implanted eyes at postoperative 6 months. Monoocular UIVA results in the ReZoom-implanted eyes were significantly better than the Tecnis-implanted eyes. Ninety percent of the patients (18/20) achieved a binocular UIVA of 0.1 logMAR or better. Lubiński et al.³³ reported that 90% of their patients achieved a binocular UIVA of 0.0 logMAR at 6 months postoperatively. However, they evaluated UIVA at 60 cm in their study, whereas it was evaluated at 100 cm in our study.

In Hütz et al.³² study, none of the ReZoom-implanted eyes achieved a UNVA of 0.1 logMAR or better, compared with 60% of the Tecnis ZM900-implanted eyes at postoperative 3 months. Sixty percent of the patients achieved a binocular UNVA of 0.1 logMAR or better. In our study, 25% of the ReZoom-implanted eyes achieved an UNVA of 0.1 logMAR or better, compared with 45% of the Tecnis ZMA00-implanted eyes at 6 months postoperatively. Seventy-five percent of the patients achieved a binocular UNVA of 0.1 logMAR or better. In both studies, UNVA results in the Tecnis eyes were better than in the ReZoom-implanted eyes; however, the difference was statistically significant only in Hütz et al.³² study.

When the “mix and match” approach is used, it is usually recommended to implant the refractive multifocal IOL in the dominant eye.³⁴ However, Yoon et al.³⁵ suggest implanting the diffractive multifocal IOL in the dominant eye if the patient frequently performs near-distance work, and recommend implanting the refractive ReZoom in the dominant eye if the patient frequently performs intermediate-distance work. Implantation of the diffractive multifocal IOL to the dominant eye may be an option in special conditions.

In the present study, best patient-preferred reading distance was significantly closer in the Tecnis eyes. Reading speed can provide useful information regarding a patient’s functional visual performance. In the current study, no statistically significant difference was found between the ReZoom- and Tecnis-implanted eyes in terms of reading speed. As expected, mean binocular reading speed was higher than monocular reading speed due to binocular summation. Chen et al.³⁶ and Hütz et al.³² also reported that “mix and match” eyes achieved satisfactory reading speed and reading acuity under both low and high illumination levels.

Buckhurst et al.³⁷ compared the defocus curves of 4 groups of 15 patients implanted with bilateral Softec monofocal IOL, bilateral ReZoom multifocal IOL, bilateral Tecnis ZM900 multifocal IOL, or “mix and match” with ReZoom implanted in the right eye and Tecnis ZM900 in the left eye. Best distance corrected intermediate visual acuity was significantly better in the ReZoom group when compared with the monofocal and Tecnis ZM900 groups, while there was no significant difference between the ReZoom group and the “mix and match” group. Best distance corrected near visual acuity was significantly better in the Tecnis group compared to the monofocal and ReZoom groups, whereas no significant difference was observed between the Tecnis group and the “mix and match” group. The “mix and match” group showed similar results to both the ReZoom and Tecnis groups. In the present study, we found a statistically significant superiority of the ReZoom eyes at -0.5 D (distance vision) whereas the Tecnis ZMA00 eyes were statistically better between -3.0 and -5.0 D (near vision). No statistically significant difference in intermediate vision was observed between the ReZoom- and Tecnis-implanted eyes. Binocular vision significantly outperformed the ReZoom-implanted eyes for near vision (-2.5 to -5.0 D) and the Tecnis-implanted eyes for distance and intermediate vision (+1.5 to -2.0 D). These results suggest that the “mix and match” approach provides the advantages of the both designs and enhances visual performance.

Multifocal IOL implantation can cause reduced contrast sensitivity, but this reduction does not appear to differ between diffractive and refractive multifocal IOLs.³⁸ However, Terwee et al.³⁹ showed that although the Tecnis ZM900 and ZMA00 models were not affected by pupil diameter, ReZoom NXG1 was affected by pupil diameter, and pupil dilation in low light resulted in decreased contrast sensitivity in ReZoom MIOL-implanted eyes. On the other hand, Yoon et al.³⁵ reported that there was no statistically significant difference between ReZoom NXG1 and Tecnis ZM900 multifocal IOLs under both photopic and mesopic conditions, and the contrast sensitivity levels were good both in low and high frequencies. In the present study, photopic and mesopic contrast sensitivity levels at all spatial frequencies were within normal limits in the ReZoom NXG1 and Tecnis ZMA00 eyes throughout follow-up. We observed that binocular contrast sensitivity levels were higher than those in ReZoom and Tecnis eyes, but the difference was not statistically significant. In Lubiński et al.’s study,³³ binocular distance photopic and mesopic and binocular near photopic contrast sensitivity levels were in normal limits even at high frequency. In addition, they stated that the binocular contrast sensitivity results were better at postoperative 6 months compared to results at 3 months.

Photic phenomena such as glare and halo occur as a result of multiple unfocused images.⁴⁰ In Goes’s³¹ series, 12 of 20 patients reported photic symptoms and only one patient reported severe photic phenomena. Lubiński et al.³³ reported that none of the patients had severe halo or glare symptoms; however, 75% of the patients had some glare and halo phenomena, especially in low-light conditions. Hütz et al.³² also indicated that mild halos and severe glare were observed in 47% and 40% of their patients, respectively. Yoon et al.³⁵ reported that photic phenomena persisted in the unilateral groups, while the symptoms decreased over time in the bilateral “mix and match” group. They suggested that the lack of these photic phenomena in the phakic eyes of the unilateral group may have prevented their neuroadaptation to the new visual disturbances. In present study, 2 patients (10%) reported moderate, and 8 patients (40%) reported mild halo and glare symptoms at 6 months postoperatively. The patients expressed that the photic symptoms did not disturb them in their daily lives. The success of the multifocal IOL depends on the brain’s neuroadaptation time.⁴¹ The long phase of neuroadaptation takes 3-12 months. Before final assessment of visual performance and patient satisfaction, it is important to allow sufficient time for neuroadaptation. None of our patients required explantation of multifocal IOL during follow-up.

In the current study, patient satisfaction was over 90% in terms of distance and near vision and social functions according to NEI VFQ-25 survey results. Satisfaction during driving was 97% among the patients who drove daily (n=10). Yamauchi et al.⁴² presented a visual performance comparison between bilateral implantation of the Tecnis monofocal IOL and Tecnis multifocal IOL (ZMA00/ZMB00). When the NEI VFQ-25 scores were evaluated, only nighttime driving score was significantly worse in the multifocal group than the monofocal group. In our study, 95% of the patients reported that their satisfaction from visual performances was “perfect or very good” and 95% stated that they would recommend this method to other patients. All of the studies using the “mix and match” approach have yielded high levels of patient satisfaction and spectacle independency.^18,31,32,33 The “mix and match” approach can provide satisfactory results in selected patients who have realistic expectations and high motivation for a wide range of spectacle-free visual functions.

Conclusion

In conclusion, the “mix and match” implantation of multifocal IOLs in conjunction with proper patient selection can be considered a good option for the correction of pseudophakic presbyopia. This approach can provide satisfactory visual acuity levels at all distances, high patient satisfaction, and spectacle independence. The most important factors for high patient satisfaction are appropriate patient selection, correct IOL power calculation, and uneventful surgery.

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