Journal of Refractive Surgery

Original Article Supplemental Data

Effect of Decentration on the Optical Quality of Monofocal, Extended Depth of Focus, and Bifocal Intraocular Lenses

Jie Xu, MD, PhD; Tianyu Zheng, MD, PhD; Yi Lu, MD, PhD

Abstract

PURPOSE:

To compare the effect of intraocular lens (IOL) decentration on the optical quality in patients with implantation of three IOLs: monofocal, extended depth of focus (EDOF), and bifocal.

METHODS:

Patients had cataract surgery with implantation of one of the three above-mentioned IOLs. Higher order aberrations (HOAs), modulation transfer function (MTF), point spread function (PSF), retinal straylight, and dysphotopsia phenomena were evaluated 3 months after surgery. IOL decentration was quantified as the distance between the visual axis center and the IOL center using the OPD-Scan III aberrometer (Nidek Co., Ltd., Gamagori, Japan). The patients who received each IOL type were then divided into two subgroups (decentration of ⩽ 0.25 or > 0.25 mm) to analyze the effect of IOL decentration on these optical qualities.

RESULTS:

The study included 54 eyes (54 patients), with 18 eyes in each IOL group. The distance of IOL decentration did not differ significantly among the three groups. With a decentration of more than 0.25 mm, MTF, PSF, and coma were only significantly deteriorated in the bifocal IOL (ZMB00; Abbott Medical Optics, Santa Ana, CA). HOAs, coma, PSF, and glare perception were better in the monofocal and EDOF IOLs than those in the ZMB00 IOL when decentration was more than 0.25 mm. Furthermore, IOL decentration was significantly correlated with HOAs, coma, MTF, and PSF in the ZMB00 IOL.

CONCLUSIONS:

The monofocal and EDOF IOLs are more immune to optical quality degradation caused by IOL decentration than the ZMB00 IOL.

[J Refract Surg. 2019;35(8):484–492.]

Abstract

PURPOSE:

To compare the effect of intraocular lens (IOL) decentration on the optical quality in patients with implantation of three IOLs: monofocal, extended depth of focus (EDOF), and bifocal.

METHODS:

Patients had cataract surgery with implantation of one of the three above-mentioned IOLs. Higher order aberrations (HOAs), modulation transfer function (MTF), point spread function (PSF), retinal straylight, and dysphotopsia phenomena were evaluated 3 months after surgery. IOL decentration was quantified as the distance between the visual axis center and the IOL center using the OPD-Scan III aberrometer (Nidek Co., Ltd., Gamagori, Japan). The patients who received each IOL type were then divided into two subgroups (decentration of ⩽ 0.25 or > 0.25 mm) to analyze the effect of IOL decentration on these optical qualities.

RESULTS:

The study included 54 eyes (54 patients), with 18 eyes in each IOL group. The distance of IOL decentration did not differ significantly among the three groups. With a decentration of more than 0.25 mm, MTF, PSF, and coma were only significantly deteriorated in the bifocal IOL (ZMB00; Abbott Medical Optics, Santa Ana, CA). HOAs, coma, PSF, and glare perception were better in the monofocal and EDOF IOLs than those in the ZMB00 IOL when decentration was more than 0.25 mm. Furthermore, IOL decentration was significantly correlated with HOAs, coma, MTF, and PSF in the ZMB00 IOL.

CONCLUSIONS:

The monofocal and EDOF IOLs are more immune to optical quality degradation caused by IOL decentration than the ZMB00 IOL.

[J Refract Surg. 2019;35(8):484–492.]

With the evolution of surgical techniques and increased patient awareness, cataract surgery has recently become a refractive procedure. The main goal has shifted from restoring eyesight to improving visual performance over the greatest variation of distances possible. To date, monofocal intraocular lenses (IOLs) are the most common type of lenses used after phacoemulsification surgery and can provide excellent uncorrected distance vision (UDVA). However, these patients often need spectacle correction for near vision, which is associated with a decline in quality of life.1 Previous studies have shown that both traditional multifocal IOLs and newly developed extended depth of focus (EDOF) IOLs can provide useful pseudoaccommodation for these patients.2–4 One of the most frequently used multifocal IOLs is the diffractive bifocal IOL. This pattern splits light into two focal planes, providing a focused image with zero-order diffraction for distance vision and first-order diffraction for near vision. The EDOF IOL combines an achromatic technology and a proprietary diffractive echelette. The correction of chromatic aberrations by achromatic technology has been shown to improve retinal image contrast.5 The diffractive echelette design works by focusing incoming waves in an extended longitudinal plane, which is meant to eliminate the overlapping of near and far images induced by traditional multifocal IOLs, thereby providing better optical quality in the elongated range than multifocal IOLs.2,6

Nonetheless, despite the aforementioned advantages of the multifocal and EDOF IOLs over the monofocal IOL, one major concern is the impact of IOL decentration on postoperative optical performance. Previous studies have demonstrated that the more optically sophisticated the IOL design, the greater the sensitivity to IOL displacement.7,8 These studies have shown the performance of aberration-correcting IOL is most affected by decentration, followed by the aberration-free IOL, whereas the spherical IOL is entirely unaffected by decentration.7,8 The multifocal IOL has a far more complex optical design than the aberration-correcting IOL, which is also sensitive to decentration.9–11 To the best of our knowledge, there has been no comparative study that simultaneously analyzes the impact of decentration on optical quality among the monofocal, bifocal, and EDOF IOLs.

The main purpose of this prospective study was to compare the optical quality of the monofocal, EDOF, and bifocal IOLs and the effects of IOL decentration on the optical quality among the three IOLs.

Patients and Methods

This study was approved by the ethics committee of the Eye and Ear, Nose, and Throat Hospital of Fudan University and was conducted according to the principles of the Declaration of Helsinki. This prospective, nonrandomized, comparative clinical study enrolled patients who had cataract surgery with implantation of a Tecnis monofocal IOL (ZCB00; Abbott Medical Optics, Santa Ana, CA), Tecnis EDOF IOL (ZXR00; Abbott Medical Optics), or Tecnis +4.00 diopters (D) bifocal IOL (ZMB00; Abbott Medical Optics). All three IOL models have an anterior aspheric surface (−0.27 µm of spherical aberration). The specific details concerning the theoretical advantages, limitations, and price of these three IOLs were provided and the final choice was left to the patient.

All patients provided informed consent. The inclusion criteria were a diagnosis of age-related cataract, axial length of 20 to 26 mm, and corneal astigmatism of less than 1.50 D. The exclusion criteria included the presence of any other eye pathology or neuropathy, including trauma, corneal disease, glaucoma, chronic or recurrent uveitis, fundus pathology, and previous ocular surgery.

Preoperative Examinations

All patients underwent routine preoperative examinations for cataract surgery including the measurement of uncorrected distance visual acuity (UDVA) (logMAR), slit-lamp microscopy, fundus examination, corneal endothelium count, corneal topography, assessment with IOLMaster 500 (Carl Zeiss AG, Oberkochen, Germany), and B-mode ultrasound scan. The OPD-Scan III aberrometer (Nidek Co., Ltd., Gamagori, Japan) provided information on pupil size and angle kappa under photopic and mesopic lighting conditions.

Surgical Technique

All surgeries were performed by one experienced surgeon (YL) using a standard phacoemulsification technique. A 2.6-mm clear cornea incision was made, followed by the continuous curvilinear capsulorhexis and implantation of the IOL in the capsular bag. In the IOL power calculations, the SRK-T formula was used for eyes with an axial length of 22 to 26 mm and the Hoffer Q formula was used for eyes with an axial length of 20 to 22 mm. The postoperative medications given were levofloxacin four times a day for 1 week, prednisolone acetate four times a day for 2 weeks, and pranoprofen four times a day for 4 weeks.

3-Month Postoperative Examinations

Postoperative follow-up examinations were performed 3 months after surgery. The following tests were performed: UDVA, corrected distance visual acuity (CDVA), uncorrected intermediate visual acuity (UIVA) at 80 cm, and uncorrected near visual acuity (UNVA) at 33 cm.

The following variables regarding the optical quality were evaluated with the OPD-Scan III aberrometer: the root mean square (RMS) of the total (ocular) and intraocular wave aberrations for higher order aberrations (HOAs), modulation transfer function (MTF), and point spread function (PSF). A metric for the MTF was provided as the area ratio value (the ratio of the area under the MTF curve of the actual eye and the area under the curve of a perfect optical system). The PSF was analyzed using the Strehl ratio value, which is defined as the ratio of the peak of the ocular optical system's image intensity from a light-point source compared to the maximum attainable intensity for an ideal optical system. All of the above-mentioned measurements were reported at both 3-mm and 5-mm pupil diameters. Retinal stray-light measurement was performed with the C-Quant straylight meter (Oculus Optikgeräte GmbH, Wetzlar, Germany). Finally, the subjective perception of halos and glare were evaluated using two direct 4-point scale Likert-type questions (1 = severe; 2 = moderate; 3 = slight; 4 = none). A higher score indicated better reported optical quality.

IOL decentrations were evaluated using the OPD-Scan III aberrometer.11,12 In the retrobulbar illumination analysis mode, the instrument identifies the center of the visual axis and the diffraction ring in the ZMB00 and EDOF IOLs (Figure 1). For the monofocal IOL, the center of the IOL was identified based on the edge of the IOL; therefore, the pupil must be dilated sufficiently. Overall decentration, defined as the distance between the visual axis center and the IOL center, was then measured. Vertical and horizontal IOL decentration values were also determined. To evaluate the effect of IOL decentration on the optical quality for the three IOL groups, we further divided the patients of each IOL group into two subgroups (with overall decentration of ≤ 0.25 mm or > 0.25 mm).

The measurement of the intraocular lens (IOL) decentration by OPD-Scan III (Nidek Co., Ltd., Gamagori, Japan). The IOL decentration value in this study was defined as the distance between the center of the visual axis and the center of the IOL. The OPD-Scan III aberrometer could automatically identify the center of the visual axis (big blue plus sign) and the center of the IOL (black dot) was the circle center of the IOL diffraction ring or the edge of the IOL. The distance from the big blue plus sign to the black dot was then measured as the IOL decentration value, which was represented as the orange line.

Figure 1.

The measurement of the intraocular lens (IOL) decentration by OPD-Scan III (Nidek Co., Ltd., Gamagori, Japan). The IOL decentration value in this study was defined as the distance between the center of the visual axis and the center of the IOL. The OPD-Scan III aberrometer could automatically identify the center of the visual axis (big blue plus sign) and the center of the IOL (black dot) was the circle center of the IOL diffraction ring or the edge of the IOL. The distance from the big blue plus sign to the black dot was then measured as the IOL decentration value, which was represented as the orange line.

Statistical Analysis

All measurement data are presented as means ± standard deviations (SD). The normality of data distribution was evaluated using the Kolmogorov–Smirnov test. When parametric analysis was possible, one-way analysis of variance with Bonferroni adjustment was applied to compare the analyzed parameters among the IOLs, whereas the Kruskal–Wallis test was used when parametric analysis was not possible. A chi-square test was used to examine differences in sex distribution. The Mann–Whitney test was used to compare the two decentration subgroups of each IOL model. The relationships between the optical quality parameters and overall decentration were assessed using Spearman's correlation coefficients. A P value less than .05 was considered statistically significant. All statistical analyses were performed using SPSS software (version 22.0; IBM Corporation, Armonk, NY).

Results

Overall, 54 eyes (54 participants) were enrolled in this study; there were 18 eyes (18 participants) in each of the monofocal, ZMB00, and EDOF groups. All patients completed a follow-up visit 3 months after the procedure. Table 1 shows the patients' demographic data. No significant intergroup differences were identified for preoperative baseline information, including the UDVA, corneal astigmatism, pupil size, and angle kappa. Postoperative UDVA and CDVA also did not differ significantly among the three groups (P = .487 for UDVA and P = .775 for CDVA). The UIVA was better in the EDOF IOL group than that in the monofocal IOL group (P = .001) and the ZMB00 IOL group (P < .001). The EDOF IOL and ZMB00 IOL groups presented significantly better UNVA than the monofocal IOL group (P < .01), and the ZMB00 IOL group had significantly better UNVA than the EDOF IOL group (P = .045). The distribution of postoperative visual acuity and refractive outcomes of the three groups is presented in Figure 2.

Demographic Data (Mean ± SD) of All Patients in the Three IOL Groups

Table 1:

Demographic Data (Mean ± SD) of All Patients in the Three IOL Groups

Standard graphs for refractive outcomes for intraocular lens (IOL)–based refractive surgery. (A) Visual acuity in monofocal IOL; (B) visual acuity in extended depth of focus (EDOF) IOL; (C) visual acuity in ZMB00 IOL (Abbott Medical Optics, Santa Ana, CA); (D) uncorrected distance visual acuity (UDVA) vs corrected distance visual acuity (CDVA); (E) spherical equivalent refraction accuracy; (F) postoperative refractive cylinder. UIVA = uncorrected intermediate visual acuity; UNVA = uncorrected near visual acuity; D = diopters

Figure 2.

Standard graphs for refractive outcomes for intraocular lens (IOL)–based refractive surgery. (A) Visual acuity in monofocal IOL; (B) visual acuity in extended depth of focus (EDOF) IOL; (C) visual acuity in ZMB00 IOL (Abbott Medical Optics, Santa Ana, CA); (D) uncorrected distance visual acuity (UDVA) vs corrected distance visual acuity (CDVA); (E) spherical equivalent refraction accuracy; (F) postoperative refractive cylinder. UIVA = uncorrected intermediate visual acuity; UNVA = uncorrected near visual acuity; D = diopters

Optical Quality Outcomes

Figure 3 shows the optical quality data regarding aberrations in the three IOL groups. Ocular and internal aberrations showed no significant intergroup differences. An intergroup comparison of the MTF at different spatial frequencies at 3- and 5-mm pupil diameters is provided in Figure 4. No significant differences among the three groups were found for any spatial frequency evaluated. However, the monofocal IOL and EDOF IOL groups had slightly higher area ratio values of the MTF than the ZMB00 IOL group, albeit without statistical significance (all P > .05) (Table 2). The Strehl ratio values and retinal straylight were similar in the three IOL groups, whereas the monofocal IOL and EDOF IOL groups showed in-significantly better scores for subjective perception of glare and halos than the ZMB00 IOL group (all P > .05) (Table 2).

Intergroup comparison of ocular (left) and intraocular (right) aberrations among three intraocular lens (IOL) groups at different pupil diameters (PDs). Error bars represent standard errors of the mean. No significant differences were observed among the three IOL groups for any aberration data. The ZMB00 IOL is manufactured by Abbott Medical Optics, Santa Ana, CA. HOAs = higher order aberrations; RMS = root mean square; EDOF = extended depth of focus

Figure 3.

Intergroup comparison of ocular (left) and intraocular (right) aberrations among three intraocular lens (IOL) groups at different pupil diameters (PDs). Error bars represent standard errors of the mean. No significant differences were observed among the three IOL groups for any aberration data. The ZMB00 IOL is manufactured by Abbott Medical Optics, Santa Ana, CA. HOAs = higher order aberrations; RMS = root mean square; EDOF = extended depth of focus

Comparison of the mean modulation transfer function values among the three intraocular lens (IOL) groups at different spatial frequencies under different pupil diameters (PDs). Error bars represent standard errors of the mean. No significant differences were observed among the three IOL groups for any of the spatial frequencies. The ZMB00 IOL is manufactured by Abbott Medical Optics, Santa Ana, CA. EDOF = extended depth of focus; cpd = cycles per degree

Figure 4.

Comparison of the mean modulation transfer function values among the three intraocular lens (IOL) groups at different spatial frequencies under different pupil diameters (PDs). Error bars represent standard errors of the mean. No significant differences were observed among the three IOL groups for any of the spatial frequencies. The ZMB00 IOL is manufactured by Abbott Medical Optics, Santa Ana, CA. EDOF = extended depth of focus; cpd = cycles per degree

Intergroup Comparison of Optical Quality Outcomes (Mean ± SD)

Table 2:

Intergroup Comparison of Optical Quality Outcomes (Mean ± SD)

IOL Decentration

Figure 5 shows the distribution of IOL decentrations in the eyes with the three IOL models. The IOL decentration distance was 0.26 ± 0.13, 0.25 ± 0.11, and 0.25 ± 0.15 mm in the monofocal, EDOF, and ZMB00 group, respectively, with no significant intergroup difference (P = .748). Additionally, no significant intergroup differences were found for the horizontal decentration values (0.20 ± 0.12 mm with the monofocal IOL, 0.19 ± 0.13 mm with the EDOF IOL, and 0.17 ± 0.14 mm with the ZMB00 IOL; P = .581) or the vertical decentration values (0.13 ± 0.10 mm with the monofocal IOL, 0.13 ± 0.09 mm with the EDOF IOL, and 0.14 ± 0.12 mm with the ZMB00 IOL; P = .942).

Decentration of each intraocular lens (IOL) type relative to the visual axis center. The ZMB00 IOL is manufactured by Abbott Medical Optics, Santa Ana, CA. EDOF = extended depth of focus

Figure 5.

Decentration of each intraocular lens (IOL) type relative to the visual axis center. The ZMB00 IOL is manufactured by Abbott Medical Optics, Santa Ana, CA. EDOF = extended depth of focus

Decentration Tolerance

We divided the patients of each IOL group into a low decentration subgroup (≤ 0.25 mm; 9 eyes in the monofocal IOL group, 9 eyes in the EDOF IOL group, and 12 eyes in the ZMB00 IOL group) and a high decentration subgroup (> 0.25 mm; 9 eyes in the monofocal IOL group, 9 eyes in the EDOF IOL group, and 6 eyes in the ZMB00 IOL group).

Comparison of the Optical Quality Between the Two Decentration Subgroups Within Each IOL Group

The ZMB00 IOL group presented a significant deterioration of ocular coma at a 3-mm pupil diameter and internal coma at a 5-mm pupil diameter in the high decentration subgroup when compared to the low decentration subgroup (P = .018 and .005, respectively) (Figure 6). The MTF and PSF values at a 5-mm pupil diameter were also significantly degraded in the high decentration subgroup of the ZMB00 IOL group (P = .041 and .018, respectively) (Table 3). No significant differences in the optical quality parameters were observed between the two subgroups within the monofocal group and the EDOF IOL group.

Comparison of the aberrations between the two decentration subgroups within each intraocular lens (IOL) group. Error bars represent standard errors of the mean. *Statistically significant difference between the two decentration subgroups (P < .05). The ZMB00 IOL is manufactured by Abbott Medical Optics, Santa Ana, CA. ⩽ 0.25 mm = overall IOL decentration ⩽ 0.25 mm; > 0.25 mm = overall IOL decentration > 0.25 mm; HOAs = higher order aberrations; RMS = root mean square; EDOF = extended depth of focus; pupil diameter = PD

Figure 6.

Comparison of the aberrations between the two decentration subgroups within each intraocular lens (IOL) group. Error bars represent standard errors of the mean. *Statistically significant difference between the two decentration subgroups (P < .05). The ZMB00 IOL is manufactured by Abbott Medical Optics, Santa Ana, CA. ⩽ 0.25 mm = overall IOL decentration ⩽ 0.25 mm; > 0.25 mm = overall IOL decentration > 0.25 mm; HOAs = higher order aberrations; RMS = root mean square; EDOF = extended depth of focus; pupil diameter = PD

Comparison of Optical Quality Between the Two Decentration Subgroups Within the Three IOL Groups (Mean ± SD)

Table 3:

Comparison of Optical Quality Between the Two Decentration Subgroups Within the Three IOL Groups (Mean ± SD)

Comparison of the Optical Quality Among the High Decentration Subgroups of the Three IOL Types

The optical quality parameters did not differ significantly among the low decentration subgroups that received the three IOL types (data not shown). However, significant differences were found among the high decentration subgroups of the three IOL types. The mean overall IOL decentration of the high decentration subgroup did not differ significantly among the three IOL types (Table 4). The ocular HOAs and ocular coma aberrations at a 5-mm pupil diameter, the ocular HOAs at a 3-mm pupil diameter, and the intraocular HOAs at a 5-mm pupil diameter were all higher in the ZMB00 IOL group than those in the monofocal group and the EDOF IOL group, although statistical significance was only obtained when compared with the monofocal group (Figure 7). The PSF values at a 5-mm pupil diameter were significantly better in the monofocal and EDOF IOL groups than those in the ZMB00 IOL group (P = .048 for the monofocal IOL group and P = .025 for the EDOF IOL group) (Table 4). The monofocal IOL and EDOF IOL groups consistently obtained significantly better scores for glare perception than the ZMB00 IOL group (both P = .009) (Table 4). No significant differences were observed for the other optical quality parameters (Figure 7, Table 4).

Intergroup Comparison of Optical Quality Outcomes Among the High Decentration Subgroups of the Three IOL Types (Mean ± SD)

Table 4:

Intergroup Comparison of Optical Quality Outcomes Among the High Decentration Subgroups of the Three IOL Types (Mean ± SD)

Comparison of the aberrations among the high decentration subgroups (overall IOL decentration > 0.25 mm) of the three intraocular lens (IOL) types. Error bars represent standard errors of the mean. *Statistically significant difference between the values provided by the monofocal group and the bifocal group (P < .05). The ZMB00 IOL is manufactured by Abbott Medical Optics, Santa Ana, CA. HOAs = higher order aberrations; RMS = root mean square; EDOF = extended depth of focus; pupil diameter = PD

Figure 7.

Comparison of the aberrations among the high decentration subgroups (overall IOL decentration > 0.25 mm) of the three intraocular lens (IOL) types. Error bars represent standard errors of the mean. *Statistically significant difference between the values provided by the monofocal group and the bifocal group (P < .05). The ZMB00 IOL is manufactured by Abbott Medical Optics, Santa Ana, CA. HOAs = higher order aberrations; RMS = root mean square; EDOF = extended depth of focus; pupil diameter = PD

Correlation Between Decentration and Optical Quality

We further analyzed the relationships between these above-mentioned optical quality parameters with significant intergroup differences and the overall IOL decentration using Spearman's correlation coefficient (Table A, available in the online version of this article). In the ZMB00 IOL group, we found that the overall decentration had a certain correlation with the ocular HOA at a 3-mm pupil diameter (r = 0.544, P = .019), the ocular HOA at a 5-mm pupil diameter (r = 0.486, P = .041), the intraocular coma at a 5-mm pupil diameter (r = 0.638, P = .004), the MTF values at a 5-mm pupil diameter (r = −0.515, P = .029), and the PSF values at a 5-mm pupil diameter (r = −0.535, P = .022), whereas no significant correlation between the IOL decentration and any type of optical quality parameters was found in the monofocal IOL or EDOF IOL groups.

Correlation Between the Overall IOL Decentration and the Optical Quality Data

Table A:

Correlation Between the Overall IOL Decentration and the Optical Quality Data

Discussion

There have been several studies comparing the visual performance of the monofocal, EDOF, and multifocal IOLs. However, to the best of our knowledge, no clinical reports compared the impact of IOL decentration on the optical performance of the three IOL groups. This study assessed the influence of decentration on the optical quality of the monofocal, EDOF, and bifocal (ZMB00) IOL of an identical IOL platform, and found a better tolerance to potential degradation of optical quality caused by IOL decentration in the monofocal and EDOF IOLs than in the ZMB00 IOL.

We used an OPD-Scan III aberrometer to assess the IOL decentration, which is a convenient and reliable method.11,12 It has been reported that with continuous curvilinear capsulorhexis and in-the-bag IOL placement, the mean IOL decentration was approximately 0.2 to 0.4 mm.11,13–15 The average IOL decentration values (0.26 mm in the monofocal IOL group and 0.25 mm in the EDOF and ZMB00 IOL groups) in this study were within the normal range. No significant differences in the IOL decentration were obtained among the three IOLs, which may be related to the identical IOL platform.

When the overall IOL decentration was more than 0.25 mm, the coma aberrations, MTF, and PSF values were significantly deteriorated compared with the low decentration subgroup in the ZMB00 group. Our findings concur with the study by Zhu et al.,11 which demonstrated that inferior decentrations (0.21 ± 0.29 mm) of the multifocal IOLs may relate to higher HOAs and coma aberrations. Montés-Micó et al.10 also reported that when the multifocal IOL was decentered in the direction of the add sector (0.2 to 0.4 mm), the cut-off frequency of MTF was reduced to approximately 40 cycles per degree. The PSF was slightly deteriorated when the multifocal IOL was decentered by 0.2 and 0.4 mm.

On the other hand, we did not observe any significant deterioration of optical quality data in the other two IOL groups when decentration was more than 0.25 mm, which is in agreement with previous studies that have concluded that aspheric monocular IOL and EDOF IOL are not influenced by decentration up to 0.5 mm.16,17

Therefore, although the optical quality parameters did not differ significantly among the three IOL groups within the total study group, when an analysis of the optical quality data among the high decentration subgroups of the three IOL types was performed, the monofocal and EDOF IOL groups presented significantly lower HOAs and coma aberrations, together with significantly higher PSF values and glare perception scores, than the ZMB00 IOL group. Previous studies have also reported that the optical quality degradation was higher in the postoperative multifocal IOLs than in the monofocal IOLs.8,17 In addition, an in vitro study using standardized optical bench testing by Tandogan et al.17 showed that the MTF values of the monofocal IOL were significantly better than those of the diffractive bifocal and trifocal lenses with IOL decentration exceeding 0.25 mm. In a study comparing the retinal image quality values of the EDOF contact lens with two commercial multifocals lenses, the EDOF lenses performed best with high decentration.18

Our correlation analysis further confirmed that the overall IOL decentration was negatively correlated with the MTF and PSF values, and was positively correlated with HOAs and coma aberrations only in the ZMB00 IOL group. Consistent with our findings, He et al.12 found positive correlations between the IOL decentration and the aberration data in the bifocal IOL. Although all of the three IOL types investigated in our study were aberration-correcting IOLs, no significant correlation between the IOL decentration and the optical quality was observed in the monofocal or EDOF IOL groups. This finding could be due to the small sample size and the normal IOL decentration range in our study. Baumeister et al.19 also did not find a significant correlation with Tecnis monofocal IOLs when the mean decentration value was 0.27 ± 0.16 mm.

Our results suggest that the bifocal ZMB00 IOL is the most sensitive to IOL decentration among the three IOL types. The ZMB00 is a diffractive bifocal IOL that has 32 concentric rings with a central ring of 1 mm, whereas the ZXR00 has nine concentric rings with a central ring of 1.6 mm. Consequently, the decentration of ZMB00 IOL with the smaller central ring might exert greater influence on the decrease of optical quality.

This study has some limitations to be mentioned. First, patients were not randomized into the three IOL groups. The EDOF IOL or the ZMB00 IOL was only implanted in the eyes of patients who requested spectacle independence. Moreover, we did not investigate the influence of axial decentration on optical performance because of the small sample size. Future studies with a larger sample size are necessary to validate the findings of this study.

This study reveals that the monofocal and EDOF IOLs were less susceptible to potential degradation of optical quality caused by IOL decentration than the ZMB00 IOL, thus being more appropriate for patients with potential risk of IOL decentration, such as those with posterior capsule rupture, zonular dialysis, or high myopia.11,20

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Demographic Data (Mean ± SD) of All Patients in the Three IOL Groups

ParameterMonofocal IOLEDOF IOLZMB00 IOLP
Age (y)65.06 ± 8.0862.94 ± 14.7357.94 ± 10.56.089
Sex (no. female/no. male)11/78/1012/6.374
Corneal astigmatism (D)0.68 ± 0.380.70 ± 0.360.74 ± 0.41.907
ACD (mm)3.14 ± 0.313.37 ± 0.353.24 ± 0.26.100
AL (mm)23.94 ± 0.8924.13 ± 1.0423.33 ± 0.82.055
Photopic pupil size (mm)3.11 ± 0.442.93 ± 0.623.04 ± 0.34.536
Mesopic pupil size (mm)5.13 ± 1.124.87 ± 1.115.08 ± 0.93.737
Photopic angle kappa (mm)0.28 ± 0.140.26 ± 0.100.29 ± 0.12.714
Mesopic angle kappa (mm)0.34 ± 0.190.28 ± 0.110.32 ± 0.16.461
Preoperative UDVA (logMAR)0.73 ± 0.390.63 ± 0.310.65 ± 0.31.787
Postoperative UDVA (logMAR)0.06 ± 0.100.03 ± 0.100.03 ± 0.09.487
Postoperative CDVA (logMAR)−0.03 ± 0.07−0.04 ± 0.06−0.02 ± 0.09.775
Postoperative UIVA (logMAR)0.25 ± 0.170.06 ± 0.080.28 ± 0.13< .001a; A–B = .001a; A–C 1.00; B–C < .001a
Postoperative UNVA (logMAR)0.44 ± 0.160.21 ± 0.120.08 ± 0.09< .001a; A–B = .006a; A–C < .001a; B–C .045a

Intergroup Comparison of Optical Quality Outcomes (Mean ± SD)

ParameterMonofocal IOLEDOF IOLZMB00 IOLPa
AR of MTF (3-mm PD) (%)39.61 ± 13.8239.80 ± 11.2837.87 ± 9.64.862
AR of MTF (5-mm PD) (%)40.15 ± 8.1741.95 ± 12.6638.57 ± 8.87.607
SR of PSF (3-mm PD)0.11 ± 0.080.11 ± 0.070.10 ± 0.05.776
SR of PSF (5-mm PD)0.03 ± 0.010.04 ± 0.020.03 ± 0.01.445
Retinal straylight (log units)1.36 ± 0.201.32 ± 0.241.38 ± 0.17.622
Retinal straylight (Esd)0.06 ± 0.010.06 ± 0.010.06 ± 0.01.708
Glare3.33 ± 0.843.39 ± 0.852.72 ± 1.18.139
Halos3.61 ± 0.703.67 ± 0.593.17 ± 1.10.304

Comparison of Optical Quality Between the Two Decentration Subgroups Within the Three IOL Groups (Mean ± SD)

ParameterMonofocal IOLEDOF IOLZMB00 IOL



⩽ 0.25 mm (9 Eyes)> 0.25 mm (9 Eyes)P⩽ 0.25 mm (9 Eyes)> 0.25 mm (9 Eyes)P⩽ 0.25 mm (12 Eyes)> 0.25 mm (6 Eyes)P
AR of MTF (3-mm PD) (%)39.62 ± 12.3039.59 ± 15.95.73041.81 ± 10.5337.79 ± 12.26.43640.38 ± 8.9832.83 ± 9.65.083
AR of MTF (5-mm PD) (%)39.00 ± 8.8241.30 ± 7.80.43640.33 ± 13.9843.57 ± 11.81.00041.26 ± 8.9533.20 ± 6.29.041a
SR of PSF (3-mm PD)0.10 ± 0.060.12 ± 0.09.7960.11 ± 0.070.11 ± 0.071.0000.11 ± 0.050.07 ± 0.05.213
SR of PSF (5-mm PD)0.03 ± 0.020.03 ± 0.01.3400.03 ± 0.020.04 ± 0.03.5460.03 ± 0.010.02 ± 0.01.018a
Retinal straylight (log units)1.41 ± 0.201.31 ± 0.20.5461.32 ± 0.311.31 ± 0.171.0001.33 ± 0.161.48 ± 0.17.180
Retinal straylight (Esd)0.06 ± 0.010.06 ± 0.011.000.06 ± 0.000.06 ± 0.01.6660.06 ± 0.010.06 ± 0.01.892
Glare3.11 ± 0.933.56 ± 0.73.3403.22 ± 0.973.56 ± 0.73.5463.08 ± 1.242.00 ± 0.63.083
Halos3.56 ± 0.733.67 ± 0.71.7303.56 ± 0.733.78 ± 0.44.6663.50 ± 0.802.50 ± 1.38.151

Intergroup Comparison of Optical Quality Outcomes Among the High Decentration Subgroups of the Three IOL Types (Mean ± SD)

ParameterMonofocal IOL (A) (9 Eyes)EDOF IOL (B) (9 Eyes)ZMB00 IOL (C) (6 Eyes)P
Overall decentration (mm)0.37 ± 0.070.33 ± 0.080.41 ± 0.14.315
AR of MTF (3-mm PD) (%)39.59 ± 15.9537.79 ± 12.2632.83 ± 9.65.626
AR of MTF (5-mm PD) (%)41.30 ± 7.8043.57 ± 11.8033.20 ± 6.29.118
SR of PSF (3-mm PD)0.12 ± 0.090.11 ± 0.070.07 ± 0.05.469
SR of PSF (5-mm PD)0.03 ± 0.010.04 ± 0.030.02 ± 0.01.018a; A–B = 1.00; A–C = .048a; B–C = .025a
Retinal straylight (log units)1.31 ± 0.201.31 ± 0.171.48 ± 0.17.170
Retinal straylight (Esd)0.06 ± 0.010.06 ± 0.010.06 ± 0.01.821
Glare3.56 ± 0.733.56 ± 0.732.00 ± 0.63.004a; A–B = 1.00; A–C = .009a; B–C = .009a
Halos3.67 ± 0.713.78 ± 0.442.50 ± 1.38.069

Correlation Between the Overall IOL Decentration and the Optical Quality Data

ParameterMonofocal IOLEDOF IOLZMB00 IOL



rPrPrP
Ocular RMS HOA (3-mm PD)0.001.9970.002.9930.544.019a
Ocular RMS coma (3-mm PD)−0.062.806−0.137.5880.398.102
Ocular RMS HOA (5-mm PD)0.013.9580.279.2630.486.041a
Ocular RMS coma (5-mm PD)−0.208.408−0.302.2230.351.153
Intraocular RMS HOA (5-mm PD)−0.088.729−0.155.5400.321.193
Intraocular RMS coma (5-mm PD)0.029.909−0.00.9800.638.004a
AR of MTF (5-mm PD) (%)0.239.3410.011.964−0.515.029a
SR of PSF (5-mm PD)0.314.2040.130.606−0.535.022a
Glare0.229.3600.149.554−0.294.237
Authors

From the Department of Ophthalmology (JX, TZ, YL) and Eye Institute (JX, TZ, YL), Eye and Ear, Nose, and Throat Hospital, Fudan University, Shanghai, China; Key Laboratory of Myopia, Ministry of Health, Shanghai, China (JX, TZ, YL); and Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China (JX, TZ, YL).

Supported by research grants from the National Natural Science Foundation of China (Grant No. 81670835), the Excellent Young Doctor Training Program of Shanghai (2015), and the Program for Outstanding Medical Academic Leader of Shanghai.

The authors have no financial or proprietary interest in the materials presented herein.

Drs. Xu and Zheng contributed equally to this work and should be considered as equal first authors.

AUTHOR CONTRIBUTIONS

Study concept and design (JX, TZ, YL); data collection (JX); analysis and interpretation of data (JX); writing the manuscript (JX); critical revision of the manuscript (TZ, YL); administrative, technical, or material support (YL); supervision (TZ,YL)

Correspondence: Yi Lu, MD, PhD, 83 Fenyang Road, Shanghai 200031, China. E-mail: luyieent@126.com

Received: February 26, 2019
Accepted: July 08, 2019

10.3928/1081597X-20190708-02

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