Comparison between clinical results of two diffractive multifocal lenses with the same platform but different additions

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1 ARTICLE Comparison between clinical results of two diffractive multifocal lenses with the same platform but different additions Francisco Poyales, MD 1 ; Nuria Garzón, OD, MSc 1 ; Pedro Caro, MD 1 ; Oscar Jáñez, OD 1 ; Fernando Soler, MD 1 ; Valentín Díaz, OD 1 PURPOSE: To evaluate visual results with two multifocal diffractive lenses designed with the same platform but with different additions. SETTING: Grupo Innova Ocular clinics. METHODS: A total of 50 eyes from 50 patients were included. Group 1 (n = 25) was implanted with the TECNIS 1 ZLB and group 2 (n = 25) with the TECNIS 1 ZKB Patients were assessed at 24 hours, 1 week and 1 month postoperatively. At surgical discharge, corrected (CDVA) and uncorrected distance visual acuity (UCDVA), near visual acuity (VA) at 25, 40 and 80 cm, visual quality and the defocus curve were measured. RESULTS: Changes in sphere and spherical equivalent were statistically significant (p<0.01) in both groups at 1 week and 1 month compared to preoperative values. In group 1, UCDVA logmar at 1 month was 0.06 ± In group 2, UCDVA at 1 month was 0.03 ± In near vision, the TECNIS 1 ZLB group obtained a VA logmar of 0.35 ± 0.02 at 25 cm, 0.13 ± 0.02 at 40 cm and 0.27 ± 0.02 at 80 cm, while in the TECNIS 1 ZKB group, the values were 0.38 ± 0.03, 0.14 ± 0.03 and 0.23 ± 0.06, respectively. No statistically significant differences were found either when results for visual quality were compared. CONCLUSION: Both the TECNIS 1 ZLB and TECNIS 1 ZKB are excellent options for obtaining good distance and near vision, in addition to providing good intermediate vision, especially at distances such as those required for working with computers. J Emmetropia 2015; 6: Cataract surgery is increasingly becoming a refractive surgery that seeks to give patients the best possible vision at all distances. This has contributed to the continual evolution in the design of multifocal intraocular lenses aimed at Submitted 3/3/2015 Revised 6/2/2015 Accepted 6/9/ Innova Ocular, Madrid, Spain. Financial disclosure: The authors have no commercial or proprietary interest in the products mentioned herein. Corresponding Author: Francisco Poyales Innova Ocular C/ Galileo nº , Madrid, Spain ioamadrid@hotmail.es achieving the best vision, especially at intermediate and near distances 1. Commercially available lenses include diffractive, refractive, or even combined designs, with high, medium and low additions, bifocal and trifocal models, each providing different vision. However, it is not only the patient s visual acuity that is important, but also the visual quality obtained, which requires measuring parameters that determine the optical quality of the implanted lenses 2. The aim of this study was to objectively evaluate both the visual acuity obtained at different distances, and the visual quality provided by two diffractive bifocal lenses with the same platform, but with a different addition in each case: D and D in the intraocular lens (IOL) plane SECOIR Sociedad Española de Cirugía Ocular Implanto-Refractiva ISSN:

2 66 CLINICAL RESULTS OF TWO DIFFRACTIVE MULTIFOCAL LENSES MATERIALS AND METHODS Both models of implanted lenses have the same platform, TECNIS 1 (Abbott Medical Optics, Inc.), but differ in their near additions (Table 1). Both are biconvex lenses with an anterior aspheric surface and a posterior diffractive surface. They are composed of a hydrophobic acrylic material with a UV filter and a refractive index of The total length of the lens is mm, with an optical zone of 6.00 mm. The lens has an open loop C shaped design with the ProTEC 360 continuous square frosted edge to prevent opacification of the posterior side. These models also differ with respect to other platforms in the arrangement of the haptics, which is in a plane parallel to the optic, called Tri-Fix. The TECNIS 1 ZLB model has a D addition (+2.37 D in the spectacle plane) and the TECNIS 1 ZKB model has a D addition (+2.01 D in the spectacle plane) (Table 1). The study was conducted in accordance with the ethical principles of the Declaration of Helsinki and was approved by the Innova Ocular Group Ethics Committee. All patients were subjected to the same preoperative protocol that included optical biometry with the IOL Master (Carl Zeiss AG, Oberkochen, Germany), Pentacam topography (Oculus, Wetzlar, Germany), intraocular pressure (IOP) with the Goldmann tonometer, biomicroscopic examination, optical coherence tomography with Cirrus OCT (Carl Zeiss, Dublin, California, USA) and fundus examination. The presence of more than 1.25 D of corneal astigmatism, glaucoma and/or corneal or macular pathology, or any other disease that would contraindicate implantation of a multifocal intraocular lens was considered an exclusion criterion. All lenses were implanted through a 2.2 mm incision using the Unfolder Platinum 1 Series injector (Abbott Medical Optics, Inc.) to facilitate implantation. A total of 50 eyes from 50 patients were included, with a mean age of 61.9 ± 10.3 years (range years). Table 1. IOL models with their different additions and theoretical reading distances depending on near power Addition in IOL plane (D) Addition in spectacle plane (D) Theoretical reading distance (cm) ZLB ZKB None of the patients included in the study suffered any intraoperative or postoperative complications, and all were operated according to the established protocol. All patients had at least 3 postoperative visits: at 24 hours, 1 week and 1 month after surgery. Distance VA was measured with the ETDRS chart and near VA at 25 cm, 40 cm and 80 cm were obtained with the Radner-Vissum test at both 1 week and 1 month. IOP was measured, and a complete biomicroscopic evaluation was performed. At the 1 month visit, visual quality was assessed by the objective scatter index (OSI), modulation transfer function (MTF) and Strehl ratio. These three measurements were taken with the Optical Quality Analyzer System (OQAS, Visiometrics S.L). As a final test, the defocus curve was measured from 5.00 D to D in 0.50 D steps. Statistical analysis IBM SPSS for Windows, version 19 software (IBM, Armonk, NY, USA) was used for statistical analysis. Following a Kolmogorov-Smirnov test for normality, a paired Student s t test was used when parametric analysis was possible. For all tests, a p-value < 0.05 was considered statistically significant. Pearson or Spearman correlation coefficients were used to evaluate the correlation between the different variables. RESULTS Mean axial length (AXL) was ± 0.91 mm (range mm) and mean anterior chamber depth (ACD) was 2.99 ± 0.10 mm (range mm). Mean power of the implanted IOLs was ± 3.18 D (range D). Patients were divided in two groups: Group 1, called ZLB, included 25 eyes from 25 patients, and group 2, called ZKB, included 25 eyes from 25 patients. Data from the two lens groups showed statistically significant changes (p < 0.01) in sphere and spherical equivalent at 1 week and 1 month compared to preoperative values, although there were no statistically significant differences between these two visits. Similarly, there were statistically significant differences in non-compensated vision compared to preoperative values, but these disappeared between the two postoperative visits. For the TECNIS 1 ZLB with D addition, mean uncorrected distance visual acuity (UCDVA) logmar at 1 week was 0.07 ± 0.03 and 0.06 ± 0.02 at 1 month. Mean corrected distance visual acuity (CDVA) logmar at 1 week was 0.02 ± 0.02 and 0.01 ± 0.03 at 1 month. Mean spherical equivalent at 1 week was 0.10 ± 0.17 D, but had a value of 0.02 ± 0.05 D at 1 month.

3 CLINICAL RESULTS OF TWO DIFFRACTIVE MULTIFOCAL LENSES 67 Table 2. Values obtained at assessments of TECNIS 1 ZLB lens AXL (mm) Preoperative 1 week 1 month ± 0.24 (21.33 to 25.15) ACD (mm) 2.97 ± 0.12 (2.10 to 3.95) IOL (mm) ± 0.78 (17.0 to 29.5) Spherical equivalent (D) 0.94 ± 0.63 ( 8.00 to +5.15) 0.10 ± 0.17 ( 1.25 to +0.62) 0.02 ± 0.05 ( 0.75 to +0.50) LogMAR CDVA 0.12 ± 0.03 ( 0.1 to 0.5) 0.02 ± 0.02 ( 0.1 to 0.25) 0.01 ± 0.03 ( 0.05 to 0.15) LogMAR UCDVA 0.29 ± 0.09 (0.0 to 0.7) 0.07 ± 0.03 ( 0.1 to 0.4) 0.06 ± 0.02 ( 0.1 to 0.4) LogMAR DCNVA 25 cm 0.38 ± 0.03 (0.2 to 0.6) 0.35 ± 0.02 (0.0 to 0.5) LogMAR DCNVA 40 cm 0.14 ± 0.03 (0.0 to 0.5) 0.13 ± 0.02 (0.05 to 0.3) LogMAR DCNVA 80 cm 0.23 ± 0.06 (0.1 to 0.4) 0.27 ± 0.02 (0.1 to 0.4) AXL, axial length; ACD, anterior chamber depth; IOL, intraocular lens; CDVA, corrected distance visual acuity; UCDVA, uncorrected distance visual acuity; DCNVA, distance-corrected near visual acuity For near vision, VA logmar values obtained at 1 month after surgery were 0.35 ± 0.02 for 25 cm, 0.13 ± 0.02 for 40 cm and 0.27 ± 0.02 for 80 cm (Table 2). Results obtained for the TECNIS 1 ZKB IOL with a D addition were mean UCDVA at 1 week of 0.14 ± 0.13 and 0.03 ± 0.03 at 1 month. Mean CDVA logmar obtained at 1 week was 0.06 ± 0.09, while at 1 month after surgery, all patients obtained a VA logmar of Mean spherical equivalent at 1 week was 0.20 ± 0.02, but at 1 month fell to 0.08 ± For near vision, the mean VA logmar obtained at 1 month were 0.38 ± 0.03 for 25 cm, 0.14 ± 0.03 for 40 cm and 0.23 ± 0.06 for 80 cm (Table 3). Comparison of the results obtained with the two lenses found no statistically significant differences between the two models in any of the parameters evaluated (Table 4). The mean visual quality values obtained with the TECNIS 1 ZLB lens at 1 month were OSI 1.88 ± 0.41, MTF ± 0.63 and Strehl ratio ± The values obtained for the TECNIS 1 ZKB lens were OSI 2.03 ± 0.38, MTF ± 3.06 and Strehl ratio ± 0.03, with no statistically significant differences between the two lens models (Table 5). Defocus curves were measured in the range from 5.00 D to D in 0.50 steps using the ETDRS test. The curves showed similar values for distance vision, with logmar close to 0.0. The TECNIS 1 ZLB lens achieved better near vision at 40 cm ( 2.50 lens), while the TECNIS 1 ZKB lens achieved maximum VA at a distance of 50 cm ( 2.00 lens). Best near VA, regardless of distance, was obtained with the ZKB model. In terms of intermediate vision, both lenses had very similar behavior from infinity to 80 cm (1.25 D), but from this distance to 50 cm, the ZKB model obtained better vision.

4 68 CLINICAL RESULTS OF TWO DIFFRACTIVE MULTIFOCAL LENSES Table 3. Values obtained at assessments of TECNIS 1 ZKB lens Mean (SD) Range Preoperative 1 week 1 month AXL (mm) ± 0.64 (21.31 to 24.73) ACD (mm) 3.11 ± 0.20 (2.63 to 3.70) IOL (mm) ± 2.37 (16.50 to 30.0) Spherical equivalent (D) 2.69 ± 1.44 ( 2.25 to +5.50) 0.20 ± 0.02 ( 1.5 to 0.00) 0.08 ± 0.14 ( 1.0 to +0.50) LogMAR CDVA 0.13 ± 0.17 (0.0 to 0.8) 0.06 ± 0.09 (0.1 to 0.25) 0.00 LogMAR UCDVA 0.32 ± 0.19 (0.0 to 0.7) 0.14 ± 0.13 (0.0 to 0.7) 0.03 ± 0.03 (0.0 to 0.2) LogMAR DCNVA 25 cm 0.40 ± 0.04 (0.3 to 0.5) 0.38 ± 0.03 (0.3 to 0.6) LogMAR DCNVA 40 cm 0.11 ± 0.04 (0.0 to 0.2) 0.14 ± 0.03 (0.1 to 0.3) LogMAR DCNVA 80 cm 0.22 ± 0.03 (0.15 to 0.3) 0.23 ± 0.06 (0.1 to 0.4) AXL, axial length; ACD, anterior chamber depth; IOL, intraocular lens; CDVA, corrected distance visual acuity; UCDVA, uncorrected distance visual acuity; DCNVA, distance-corrected near visual acuity DISCUSSION It is increasingly more common for cataract surgery to become refractive surgery, due to the growing number of patients requesting presbyopia surgery to correct their deficient near vision, thus increasing the number of surgeries performed in both low opacified and clear crystalline lenses. For many years now, multifocal lenses 1,3,4 have provided good distance and near vision in operated patients, and various studies have shown that different near additions play a key role in terms of the ideal reading distance with each lens One of the major differences between the TECNIS 1 Multifocal IOL and other multifocal lenses is the design of its diffractive rings. The rings of TECNIS 1 Multifocal IOLs have a sinusoidal cross-section rather than the triangular crosssection of other lenses. This smoother cross-section makes the rings less visible when observed with the biomicroscope, so that retroillumination is often required to see them. Several studies have also shown that lenses with higher additions obtain poorer intermediate-range vision than those with lower additions 5, 12. As a result, the new models launched on the market by the different commercial companies tend to incorporate similar designs to those that have been implemented for years, but with less add power to improve visual results globally. The relatively recent introduction into our daily lives of devices like smartphones or tablets leads us to constantly perform actions at distances of 30 to 40 cm on average, making lower additions more functional. As has already been demonstrated by many studies, current multifocal lens models obtain good distance vision, so the values found in our study are close to those published by other authors At 1 month postsurgery, 80% of patients with the TECNIS 1 ZLB

5 CLINICAL RESULTS OF TWO DIFFRACTIVE MULTIFOCAL LENSES 69 Table 4. Statistical differences between TECNIS 1 ZLB and TECNIS 1 ZKB lenses 1 week 1 month Sphericalequivalent (D) p = p = LogMAR CDVA p = p = LogMAR UCDVA p = p = LogMAR DCNVA 25 cm p = p = LogMAR DCNVA 40 cm p = p = LogMAR DCNVA 80 cm p = p = CDVA, corrected distance visual acuity; UCDVA, uncorrected distance visual acuity; DCNVA, distancecorrected near visual acuity Table 5. Comparison of visual quality between TECNIS 1 ZLB and TECNIS+ 1 ZKB lenses ZLB ZKB p-value OSI 1.88 ± 0.41 (0.6 to 3.5) 2.03 ± 0.38 (1.0 to 3.4) p = MTF ± 0.63 (16.72 to 52.66) ± 3.06 (14.34 to 53.18) p = Strehl ratio ± 0.03 (0.08 to 0.242) ± 0.03 (0.086 to 0.277) p = OSI, objective scatter index; MTF, modulation transfer function implant had an UCDVA of 0.10 or better, and 100% had a CDVA of 0.10 or better. Likewise, at 1 month post-surgery, 89% of patients with the TECNIS 1 ZLB implant had an UCDVA of 0.10 or better, and 100% had a CDVA of 0.00 logmar (Figures 1 and 2). In terms of intermediate vision, the behavior of both lenses was excellent when compared to other studies where TECNIS 1 lenses, with the same platform but with a addition in the IOL plane, had more defects at this distance 20. Over 90% of patients in both groups achieved values of 0.30 logmar or better for vision at 80 cm, and approximately 60% had values of 0.2 logmar or better. Vision at 80 cm can be regarded, for example, as the distance that a patient might need to perform tasks on a computer. Mean vision values with the ZKB model were slightly better at this distance (0.20 ± 0.06). At a distance of 40 cm, which can be considered as within the usual reading distance range, at 1 month post-surgery, 97% of patients with the ZLB lens achieved a distance corrected near visual acuity (DCNVA) of 0.20 or better, and 100% obtained at least 0.30 logmar at this distance. With the ZKB lens, 92% of patients achieved a vision of 0.20 or better and 100%, as in the previous group, achieved values of at least 0.3. Focusing on the mean values obtained by both groups at this distance, the values obtained with the ZLB were slightly better (0.13 ± 0.02), although there were no statistically significant differences. It was at a closer distance of 25 cm where the VA values obtained were worse when compared to the model previously marketed by Abbott, the ZMB At this distance, 26% of patients from the ZLB group achieved a VA of 0.30 or better, while this was achieved by 32% of patients in the ZKB group. The data presented here are consistent with the addition of each lens, remembering that the ZLB model is designed to obtain its peak near vision at 42 cm and the ZKB at 50 cm. This

6 70 CLINICAL RESULTS OF TWO DIFFRACTIVE MULTIFOCAL LENSES Figure 1. Distribution of postoperative visual acuity with TECNIS 1 ZLB. CDVA, corrected distance visual acuity; UCDVA, uncorrected distance visual acuity; DCNVA, distance-corrected near visual acuity. Figure 2. Distribution of postoperative visual acuity with TECNIS 1 ZKB. CDVA, corrected distance visual acuity; UCDVA, uncorrected distance visual acuity; DCNVA, distance-corrected near visual acuity. Figure 3. Defocus curves for TECNIS 1 ZLB and TECNIS 1 ZKB models. is why the ZKB delivers poorer vision at 25 cm than in the ZLB, because it is farther from its ideal point, while at 80 cm the opposite occurs. Defocus curves were measured in the range from 5.00 D to D in 0.50 steps using the ETDRS test, according to the study by Wolffsohn et al. 23 From a far distance to approximately 80 cm, the behavior of the two lenses was very similar, which is consistent with the lack of statistically significant differences between the two models for distance vision. The most significant differences were found in near vision, and the most marked factor, corroborated with the data obtained in the previously mentioned tests, was the distance at which maximum vision was achieved by each lens. Intermediate vision with the lower addition lens was slightly better than with the other model by the same manufacturer with addition, as mentioned by other authors in their studies 20, 21. It is noteworthy that in the defocus curve, in the range from far distance to 32 cm for the ZLB and to 36 cm for the ZKB, VA was at least 0.2 logmar. From those distances, both lenses reduce their VA, although the ZKB model does so more abruptly (Figure 3). It should be borne in mind, however, that these working distances are normally used less often. In terms of visual quality, the values obtained for the ZLB and ZKB models in this study were better than those presented by Alió et al. 24, where a diffractive bifocal lens (Acri.Lisa 366D, Zeiss) was compared with a multifocal lens with a sector-shaped refractive design (Oculentis GmbH, LentisMplus LS-312). However, our results were very similar to those obtained by Castillo et al. 25, where visual quality obtained with two diffractive lenses, the Acri.Lisa 366D and TECNIS 1 ZM900, was compared in terms of MTF and OSI values. In conclusion, both the TECNIS 1 ZLB and TECNIS 1 ZKB are excellent options for obtaining good distance and near vision after surgery of the crystalline lens, either opacified or not, in addition to delivering good intermediate vision, especially at distances such as that required for working with computers. The most marked difference found between the two lenses was the distance at which best near vision was obtained. Based on the above, we consider that the ZLB lens could be the ideal option for patients with a reading distance within what we could call standard ranges, from 30 to 40 cm. The ZKB lens in turn may be a good option for patients accustomed to reading at a farther distance, such as farsighted patients who were overcorrected prior to surgery, or patients who need to read at a farther distance than usual, such as musicians using a music stand. Future studies are needed to determine whether asymmetric implantation of the ZLB model in one eye and the ZKB model in the other can expand the range of near vision while maintaining optimal visual acuities.

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