- Email: [email protected]
Clinical and aberrometric evaluation of a new extended depth-of-focus intraocular lens based on spherical aberration
919
ARTICLE
Clinical and aberrometric evaluation of a new extended depth-of-focus intraocular lens based on spherical aberration Roberto Bellucci, MD, Miriam Cargnoni, OD, Carlo Bellucci, MD
Purpose: To compare the refractive, visual, and aberrometric results with a new extended depth-of-focus intraocular lens (EDOF IOL) based on alternating positive and negative spherical aberration in the central 3.0 mm optical zone and an aspheric monofocal IOL of the same platform. Setting: Ophthalmology, University Hospital of Verona, Italy. Design: Prospective case series. Methods: Cataract patients free from other ocular disease had bilateral implantation of the EDOF Mini Well IOL or the monofocal Mini IOL. Four to 6 weeks after second-eye surgery, the refraction, visual acuity, defocus curve, contrast sensitivity, and photic symptoms were assessed. Wavefront analysis was performed. The primary endpoint of was the amplitude of the dioptric interval for 0.1 logarithm of the minimum angle of
T
he quest for presbyopia correction with intraocular lenses (IOLs) has led to several solutions based on different optical approaches. Diffraction-based multifocal IOLs have been available in Europe since 1988, and there have been continuous improvements in several aspects of IOL optics and manufacturing.1–3 Refraction-based multifocal IOLs have also been studied extensively and used in clinical practice, with the zonal near addition as the most popular design at present.4–6 Pseudoaccommodating IOLs with some form of mobile or deformable optics have been used in a clinical setting; however, the clinical results have been inconsistent.7,8 More recently, IOLs based on extending the depth of focus have received attention, with the goal of obtaining seamless distance and near vision across a dioptric interval.9–11 A lower near addition, the correction of chromatic aberration, a selected change in spherical aberration, and a
resolution (logMAR) visual acuity. The secondary endpoint was an aberration comparison between the two IOLs.
Results: The study comprised two groups of 25 patients each. The corrected distance visual acuity was better with the monofocal IOL by 0.02 logMAR (P Z .03). The 0.1 logMAR dioptric interval was 2.0 diopters (D) for the EDOF IOL and 1.0 D for the monofocal IOL (P < .001). The mean CDVA at 2.0 defocus was 0.15 logMAR G 0.08 (SD) and 0.52 G 0.14 logMAR, respectively (P < .001). There was no difference in contrast sensitivity or photic symptoms. The optical aberrations at 4.0 mm and 6.0 mm aperture diameters were similar in the two groups.
Conclusion: The EDOF IOL based on spherical aberration provided greater depth of focus than the aspheric monofocal IOL without increasing optical aberrations and with few photic symptoms. J Cataract Refract Surg 2019; 45:919–926 Q 2019 ASCRS and ESCRS
combination have been adopted by IOL designers and manufacturers.9–11 The design of the new Mini Well IOL (SIFI) is based on changes in spherical aberration over the 3.0 mm central IOL surface.12 Optical bench studies indicate good depth of focus with a light-distribution profile different from that of other multifocal IOLs and extended depth-of-focus (EDOF) IOLs.13,14 Early clinical results confirmed that the new IOL provides greater depth of focus and good visual performance compared with a diffractive multifocal IOL.15 However, to our knowledge, a comprehensive study comparing the results of the Mini Well EDOF IOL and the aspheric monofocal Mini IOL (SIFI) in patients has not been published. The present study assessed the refractive, visual, and aberrometric results in two groups of patients who had bilateral implantation of the EDOF Mini Well IOL or the monofocal Mini IOL.
Submitted: September 4, 2018 | Final revision submitted: January 7, 2019 | Accepted: February 9, 2019 From the University Hospital of Verona (R. Bellucci, Cargnoni) and the University Hospital of Parma (C. Bellucci), Italy. Supported in part by SIFI, Catania, Italy. Corresponding author: Roberto Bellucci, MD, Via degli Abeti 17, Salo, Italy 25087. Email: [email protected]. Q 2019 ASCRS and ESCRS Published by Elsevier Inc.
0886-3350/$ - see frontmatter https://doi.org/10.1016/j.jcrs.2019.02.023
920
DEPTH OF FOCUS IN CATARACT PATIENTS WITH EDOF IOL
PATIENTS AND METHODS This prospective study comprised patients scheduled for bilateral cataract surgery who were free from ocular or general disease that could affect the anatomic and visual results of surgery and who had axial lengths between 22.0 mm and 26.5 mm. All patients gave informed consent to participate in the study, to receive the EDOF IOL or the monofocal IOL in both eyes according to a randomization process, and to have a postoperative examination. The study followed the tenets of the Declaration of Helsinki and was approved by the local regulative committee. Inclusion criteria were anterior corneal astigmatism on corneal topography (Sirius, Costruzione Strumenti Oftalmici) of less than 1.00 diopter (D) if with the rule (WTR) or 0.25 D if against the rule to limit the effect of posterior corneal astigmatism on postoperative refraction16 and a photopic pupil diameter on automated refraction (RK-F2, Canon, Inc.) larger than 2.0 mm. Exclusion criteria (enforced after patient enrollment) were second-eye surgery cancelled or deferred, surgical complications preventing secure in-the-bag IOL implantation in either eye, and inability to complete the follow-up program. Patients, with the exception of dropout replacements, were assigned on an alternative basis to the EDOF IOL or the monofocal IOL at the time of first-eye surgery. The axial length was measured with the Lenstar optical biometer (Haag-Streit AG). The Barrett Universal II formulaA was used to determine the IOL power, with the A constant set at 118.8 for both IOL types. Intraocular Lenses The Mini Well EDOF IOL and the Mini IOL share the same platform as follows: 25% hydrophilic acrylic, biconvex 6.0 mm optics, 4 fenestrated haptics with 5-degree angulation, posterior and anterior square-edged optics, and 10.75 mm overall length. They can be implanted through an incision smaller than 2.0 mm. The Mini IOL optic is monofocal and aspheric with 0.14 mm of negative spherical aberration at a 5.0 mm aperture diameter. The Mini Well IOL optic incorporates 2 spherical aberration profiles in the central 3.00 mm zone, a central 1.95 mm diameter zone with positive spherical aberration and a pericentral 1.05 mm wide annulus with a negative spherical aberration (Figure 1). The concept is that the combination of the 2 profiles will extend the depth of focus, providing a smooth transition between zones and a gradual power shift to support progressive vision.12 The optical design of the IOL is barely detectable on normal slitlamp observation, and the IOL looks like a monofocal IOL. Surgical Technique All surgeries were performed by the same surgeon (R.B.) using topical anesthesia. Phacoemulsification was performed with the Stellaris system (Bausch & Lomb, Inc.) through a 2.0 mm incision. The 2.0 mm incision was located on the vertical meridian when the posterior corneal with-the-rule astigmatism was 0.5 D to 1.0 D and
Figure 1. Surgical image of the new extended depth-of-focus intraocular lens.
Volume 45 Issue 7 July 2019
on the horizontal meridian in the other cases. The IOL was implanted with a 1.8 mm injector (Medicel AG). For 15 days after surgery, patients received bromfenac 0.09% eyedrops 2 times a day and a combination of tobramycin 0.3% and dexamethasone 1.0% eyedrops 4 times a day. Second-eye surgery was performed 21 to 28 days after first-eye surgery. Postoperative Evaluation Measurements were taken 4 to 6 weeks after second-eye surgery by personnel unaware which IOL was implanted. After slitlamp observation, automated refraction at a 2.2 mm aperture diameter and the photopic pupil diameter were measured using the same automated refractor as preoperatively. Monocular and binocular uncorrected (UDVA) and corrected (CDVA) distance visual acuities were measured at 4 m using the Early Treatment Diabetic Retinopathy Study chart. To achieve pseudoaccommodation, the optical correction for distance was optimized with the red–green test. Uncorrected (UIVA) and distance-corrected (DCIVA) intermediate visual acuities were measured at 60 cm and uncorrected (UNVA) and distance-corrected (DCNVA) near visual acuities at 40 cm using optotypes (Precision Vision). Defocus curves were obtained with binocular vision by randomly adding plus lenses (up to C2.0 D) and minus lenses (up to 4.0 D) in 0.5 D steps17 to the distance optical correction and then recording the visual acuity with each lens power. Contrast sensitivity was measured for distance with binocular vision and with the full optical correction in place. The computer-displayed vision chart (Costruzione Strumenti Oftalmici) presents sine-wave gratings at 1.5, 3.0, 6.0, 12.0, and 18.0 cycles per degree (cpd) with a background luminance of 85 candelas/m2.18 The mean of the log10 values for each spatial frequency was used for comparison. Optical aberrations were assessed with the KR-1D device (Topcon Corp.). This device combines Placido-disk corneal topography with Hartmann-Shack ocular aberrometry and provides the internal aberration as the difference between the 2 measurements. Because of the low influence of the posterior corneal surface on higher-order aberrations (HOAs), internal HOAs are considered to be mainly caused by the IOL.19 Evaluated were total HOAs and the following Zernike (Z) coefficients: Z3( 3,C3), which represents coma-like aberration; Z3( 1,C1), which represents coma aberration; Z4( 4,C4), which represents sphericallike aberration; and Z4(0), which represents spherical aberration. Measurements were taken in mydriasis for 4.0 mm and 6.0 mm aperture diameters. In addition, the wavefront spherical equivalent refractions at 4.0 mm and at 6.0 mm were compared. The point-spread function derived from the optical HOAs and expressed as the Strehl ratio was taken as an objective indicator of the postoperative optical quality of the eyes. The device used in the study provides point-spread function data at a 4.0 mm aperture diameter only. The subjective optical quality was assessed using a questionnaire that asked patients whether they had any of the following visual disturbances at night: glare, halos, starbursts, hazy vision, monocular polyopia, simultaneous vision, and defocus. An online test described by Kramer et al.B was adopted to evaluate the results. In this test, 3 types of halo are shown and evaluated for size and intensity as follows: type 1, disk shaped; type 2, disk shaped with starburst; type 3, ring shaped. Statistical Analysis The primary endpoint of this study was the assessment of the dioptric intervals through which the visual acuities of 0.1 logarithm of the minimum angle of resolution (logMAR) and 0.2 logMAR were maintained in binocular vision. The visual acuity at 2.0 D minus defocus (50 cm distance) was used when calculating the minimum significant sample size, with a 0.2 logMAR difference between the monofocal group and EDOF group arbitrarily selected as clinically significant. An a error of 1.0% and a b error
921
DEPTH OF FOCUS IN CATARACT PATIENTS WITH EDOF IOL
of 95.0% were adopted. Considering 0.4 logMAR G 0.1 (SD) as the mean visual acuity at 2.0 D defocus with monofocal IOLs and 0.1 logMAR as the standard error of defocus curves,17,20 a minimum of 9 patients per group was required. The secondary endpoint was the difference in optical aberrations between the two IOL groups. Of the two aperture diameters available on the aberrometer (4.0 mm and 6.0 mm), the 4.0 mm diameter was selected for sample-size calculation because it is closest to the aberration change zone of the EDOF IOL. Aberration data for monofocal IOLs and clinically significant differences were taken from the literature.19,21,22 Table 1 shows the samplesize calculation. Based on this calculation, patients were recruited until 25 patients per group were available for analysis. The 1sample Kolmogorov-Smirnov test was used to determine whether the data were normally distributed. If the data followed a normal distribution, parametric analysis was performed and if not, nonparametric statistical analysis was used.
RESULTS This study recruited 57 patients, 28 in the EDOF group and 29 in the monofocal group. Two patients in the EDOF group and 3 in the monofocal group were excluded after first-eye surgery because of health problems that required deferment of second-eye surgery. An additional 2 patients (1 per group) were unable to complete the follow-up examination and were also excluded. Thus, the analysis included 25 patients in each group (P Z 1.000), with 6 women and 19 men in the EDOF group and 9 women and 16 men in the monofocal group (P Z .538). Table 2 shows the patients’ characteristics. Surgery was uneventful in all eyes. The mean IOL power was 22.30 G 2.40 D in the EDOF group and 22.16 G 2.27 D in the monofocal group (P O .1). Refraction and Visual Acuity
Table 3 shows the postoperative automated refraction and clinical refraction assessed with the duochrome test. In the EDOF group the automated refraction (2.2 mm aperture diameter) was more myopic than the clinical refraction by 0.33 D. The postoperative photopic pupil diameter was slightly narrower than preoperatively in both IOL groups (P ! .05). Table 4 shows the visual acuity results. The binocular UDVA and monocular CDVA were slightly better in the monofocal group; the difference of 0.02 to 0.03 logMAR was statistically significant (P ! .05). The intermediate and the near visual acuities were statistically significantly
Table 1. Sample-size calculation for the aberration study at 4.0 mm aperture diameter assuming an a error of 0.01 and a b error of 0.05. Parameter HOA Sphere Z4( 4,C4) Coma Z3( 3,C3) SA Z4(0)
Mean (mm) ± SEM*
P Value
Eyes (n)
0.15 G 0.06 0.05 G 0.03 0.13 G 0.07 0.03 G 0.02
.05 .05 .07 .07
50 26 36 9
HOA Z higher-order aberrations; SA Z spherical aberration; Z Z Zernike *Monofocal
better in the EDOF group, with large between-group differences in the logMAR values. Figure 2 shows the defocus curves obtained with binocular vision. All between-group differences from 1.00 D defocus to 2.50 D defocus were statistically significant. A binocular CDVA of 0.10 logMAR or better was maintained between C0.50 D and 1.50 D of defocus in the EDOF group and between C0.50 D and 0.50 D in the monofocal group. A binocular CDVA of 0.2 logMAR or better was maintained between C1.00 D and 2.00 D of defocus and between C1.00 D and 1.00 D of defocus, respectively. For 2.00 D defocus, visual acuity was 0.15 G 0.08 logMAR in the EDOF group and was 0.52 G 0.14 logMAR in the monofocal group; the difference of 0.37 logMAR exceeded the 0.20 logMAR level considered as clinically significant. The difference in visual acuity between the EDOF group and the monofocal group was statistically significant from 0.50 D to 4.00 D of defocus. Figure 3 shows the binocular contrast sensitivity data. The overall level of the measured contrast sensitivity was as expected in patients of this age. It was slightly lower in the EDOF IOL group. The only statistically significant between-group difference was at 18 cpd (P Z .01). Aberration Data
Figure 4 shows the total ocular, corneal, and internal aberrations measured at 4.0 mm and at 6.0 mm aperture diameters. At a 4.0 mm aperture diameter, the values of total HOAs, total coma, and total sphere were in the normal range for pseudophakic eyes. The spherical aberration Z4(0) was slightly negative in both groups; the monofocal IOL induced less negative spherical aberration than the 0.14 mm (at 5.0 mm aperture diameter) reported by the manufacturer. The only the statistically significant difference was in the total HOAs and total coma, with the values being better in the EDOF group. The aberrations at a 6.0 mm aperture diameter were approximately 4-fold the aberrations at a 4.0 mm aperture diameter. There were no statistically significant differences between the IOL groups. The EDOF group had lower ocular and internal aberrations than the monofocal IOL at 4.0 mm. However, the ocular and internal aberrations at 6.0 mm were lower in the monofocal group. Both IOLs induced some positive spherical aberration at 6.0 mm. Thus, the 6.0 mm wavefront refraction was more myopic than the 4.0 mm wavefront refraction by a mean of 0.61 G 0.32 D in the EDOF group and 0.66 G 0.67 D in the monofocal group (P O .1). Objective and Subjective Optical Quality
The mean optical quality at a 4.0 mm aperture diameter, assessed using the Strehl ratio, was 0.205 G 0.112 in the EDOF group and 0.167 G 0.138 in the monofocal group (P O .1). The difference between the two groups was not statistically significant and reflects the difference in the HOAs shown in Figure 4. The aberrometer software did not provide Strehl ratio values for the 6.0 mm aperture diameter. Volume 45 Issue 7 July 2019
922
DEPTH OF FOCUS IN CATARACT PATIENTS WITH EDOF IOL
Table 2. Patient characteristics. Mean ± SD Parameter Age (y) Axial length (mm) Flat K (D) Steep K (D) Pupil diameter (mm) ACD (mm) CDVA (LogMAR) SE (D) Astigmatism (D)
EDOF IOL
Monofocal IOL
P Value
76 G 7 23.27 G 0.92 44.05 G 1.18 44.68 G 1.16 3.02 G 0.44 3.08 G 0.39 0.52 G 0.27 0.81 G 2.34 0.53 G 0.29
78 G 9 23.41 G 1.01 44.12 G 1.15 44.59 G 1.16 3.10 G 0.49 3.11 G 0.40 0.46 G 0.22 0.72 G 1.89 0.59 G 0.31
.877 .470 .764 .699 .392 .705 .226 .833 .320
ACD Z anterior chamber depth; CDVA Z corrected distance visual acuity; EDOF Z extended depth of focus; IOL Z intraocular lens; K Z keratometry; logMAR Z logarithm of the minimum angle of resolution; SE Z spherical equivalent
On the questionnaire, 7 patients (28%) in the EDOF group and 3 patients (12%) in the monofocal group reported a low degree of photic symptoms at night that did not affect driving. Regarding the images in the online test, all patients reported type 1 halo (disk shaped with no starburst), the size of which was 20% of the test scale. In the EDOF group, 4 patients (16%) reported 20% intensity and 3 patients (12%) reported 40% intensity. In the monofocal group, 2 patients (8%) reported 20% intensity and 1 patient (4%) reported 40% intensity. The difference between the two groups was not statistically significant according to the Fisher exact test. DISCUSSION The new EDOF Mini Well IOL design incorporates a modification of spherical aberration in the central optical zone, the purpose of which is to increase the depth of focus.12 In the present study, the new IOL was compared with the aspheric monofocal Mini IOL, which has the same platform. We assessed whether the new EDOF IOL design provides better optical and visual outcomes. We did not consider the corneal aberration profile during recruitment
so we could assess the ability of this IOL to provide an EDOF in unselected patients. The aberration change of the Mini Well IOL takes place in the central 3.0 mm zone and the positive spherical aberration in the central 1.95 mm zone; therefore, we were not surprised to find that the automated refraction at a 2.2 mm aperture diameter was more myopic than the clinical refraction, for which the aperture diameter is larger and the same as the pupil diameter. However, the eye is not a centered optical system; thus, evaluation of the mathematic calculation of this difference (0.33 D; P Z .071) should be done with caution. In our study, the postoperative binocular UDVA and monocular CDVA were worse in the EDOF group than in the monofocal group. However, the between-group difference in binocular CDVA was not statistically significant. The intermediate and near acuities were better in the EDOF IOL group, with DCIVA and DCNVA slightly worse than the UIVA and UNVA because of the small myopic refractive outcome. Binocularly, the DCIVA and DCNVA were statistically significantly better in the EDOF group, with a difference between the two groups of 0.32 logMAR and
Table 3. Postoperative refraction. Parameter Automated SE (D) Mean G SD Range Refractive SE (D) Mean G SD Range Automated cylinder (D) Mean G SD Range Refractive cylinder (D) Mean G SD Range Photopic pupil diameter (mm) Mean G SD
EDOF IOL
Monofocal IOL
P Value
0.59 G 0.58 0.50, 2.25
0.18 G 0.64 0.75, 1.50
.001
0.26 G 0.62 0.50, 1.50
0.20 G 0.61 0.75, 1.50
.627
0.69 G 0.37 0.00, 1.50
0.76 G 0.44 0.00, 1.75
.391
0.74 G 0.41 0.00, 1.00
0.68 G 0.47 0.00, 1.25
.498
2.83 G 0.44
2.90 G 0.46
.439
EDOF Z extended depth of focus; IOL Z intraocular lens; SE Z spherical equivalent
Volume 45 Issue 7 July 2019
923
DEPTH OF FOCUS IN CATARACT PATIENTS WITH EDOF IOL
Table 4. Postoperative visual acuity (logMAR) by group. Parameter Monocular UDVA Mean G SD Range Binocular UDVA Mean G SD Range Monocular CDVA Mean G SD Range Binocular CDVA Mean G SD Range Monocular UIVA 60 cm Mean G SD Range Monocular DCIVA 60 cm Mean G SD Range Binocular DCIVA 60 cm Mean G SD Range Monocular UNVA 40 cm Mean G SD Range Monocular DCNVA 40 cm Mean G SD Range Binocular DCNVA 40 cm Mean G SD Range
Monofocal IOL
P Value
0.16 G 0.14 0.58, 0.00
0.12 G 0.10 0.52, 0.02
.103
0.07 G 0.06 0.14, 0.00
0.04 G 0.04 0.12, 0.02
.043
0.04 G 0.05 0.14, 0.04
0.02 G 0.04 0.12, 0.06
.030
0.02 G 0.04 0.04, 0.06
0.06 G 0.04 0.04, 0.08
.084
0.16 G 0.14 0.32, 0.08
0.46 G 0.12 0.70, 0.28
!.001
0.18 G 0.08 0.28, 0.06
0.52 G 0.18 0.76, 0.30
!.001
0.16 G 0.06 0.24, 0.04
0.48 G 0.13 0.68, 0.28
!.001
0.22 G 0.12 0.34, 0.08
0.64 G 0.20 0.62, 0.24
!.01
0.24 G 0.06 0.24, 0.08
0.68 G 0.11 0.84, 0.36
!.01
0.22 G 0.08 0.16, 0.06
0.64 G 0.12 0.78, 0.32
!.01
EDOF IOL
CDVA Z corrected distance visual acuity; DCIVA Z distance-corrected intermediate visual acuity; DCNVA Z distance-corrected near visual acuity; EDOF Z extended depth of focus; IOL Z intraocular lens; K Z keratometry; logMAR Z logarithm of the minimum angle of resolution; UDVA Z uncorrected distance visual acuity; UIVA Z uncorrected intermediate visual acuity; UNVA Z uncorrected near visual acuity
0.44 logMAR, respectively; these values exceed the 0.2 logMAR level we set for clinical significance. The binocular defocus curve showed similar results, with the curve of the EDOF IOL higher than that of the monofocal IOL by 0.086 logMAR ( 1.0 D defocus), 0.37 logMAR ( 2.0 D
Figure 2. Defocus curve obtained binocularly with the distance correction in place (EDOF Z extended depth of focus; logMAR Z logarithm of the minimum angle of resolution; visual acuity Z corrected distance visual acuity).
defocus), and 0.45 logMAR ( 3.0 D defocus). The focal interval in which selected logMAR visual acuities were maintained was different between the two IOL groups; the interval for 0.1 logMAR and for 0.2 logMAR in the EDOF group was 1.0 D larger than in the monofocal IOL group. Savini et al.15 found the same intervals monocularly in
Figure 3. Binocular contrast sensitivity (*P Z .01; EDOF Z extended depth of focus; logCS Z log contrast sensitivity).
Volume 45 Issue 7 July 2019
924
DEPTH OF FOCUS IN CATARACT PATIENTS WITH EDOF IOL
Figure 4. Higher-order aberrations at 4.0 mm and 6.0 mm aperture diameter (EDOF Z extended depth of focus; HOAs Z total higher-order aberrations; RMS Z root mean square; SPH Z sphere).
20 patients who had implantation of the Mini Well IOL. The intervals compared favorably with those of a diffractive multifocal IOL. Savini et al. also studied the reading speed and concluded that the EDOF Mini Well IOL provided equal visual efficiency for distance and for near but performed better at intermediate distance.15 The contrast sensitivity data in our study are consistent with the age of our patients. Although contrast sensitivity was slightly better with the monofocal IOL, the only statistically significant between-group difference was at 18 cpd. The contrast sensitivity levels were low in our study and lower than those measured by Savini et al.15 This might be because our patients were older and the examination conditions in our study were different than those of Savini et al. We studied optical aberrations to determine the effect of the EDOF Mini Well IOL on the postoperative aberration profile in patients’ eyes. At a 4.0 mm aperture diameter, the values of total HOAs, total coma, and total sphere were in the normal range for pseudophakic eyes.19,22 However, the EDOF group had lower ocular and internal aberrations than the monofocal group at 4.0 mm. At 6.0 mm, the ocular and internal aberrations were lower in the monofocal group, although the differences were not statistically significant. Therefore, we did not find an increase in optical aberrations with the EDOF IOL compared with the aspheric monofocal IOL and the EDOF IOL did not
Volume 45 Issue 7 July 2019
increase the optical aberrations of the whole eye at 4.0 mm or 6.0 mm. The compensation for the positive central spherical aberration by the negative pericentral spherical aberration is the probable reason for this finding. To study the central differences, an aberrometer providing 2.0 mm, 2.5 mm, and 3.0 mm data should be used; such a device was not available for this study. To our knowledge, no other in vivo study has assessed optical aberrations in eyes with the EDOF Mini Well IOL. Camps et al.23 studied aberrations in vitro using an optical bench. They compared the EDOF Mini Well IOL with another EDOF IOL and a refractive multifocal IOL. Eyes with the Mini Well IOL had no 3rd-order aberration, 0.13 mm negative 4th-order aberration, or C0.12 mm positive 6th-order spherical aberration at a 3.0 mm aperture diameter. Both types of spherical aberration decreased as the aperture diameter increased.23 Camps et al. confirmed that the EDOF Mini Well IOL is based on a variation in spherical aberration, and our study shows the clinical impact of this variation. The low amount of negative spherical aberration required to extend the depth of focus was confirmed by Villegas et al.24 They induced negative spherical aberration in the nondominant eye of 17 patients who had bilateral implantation of a light-adjustable IOL and found 0.083 G 0.020 mm at a 4.0 mm aperture diameter was sufficient for reading.24 Their study also showed that both positive aberration and negative spherical aberration
DEPTH OF FOCUS IN CATARACT PATIENTS WITH EDOF IOL
can be used to extend the depth of focus. In a recent paper, Aguila-Carrasco et al.25 highlighted the importance of coma in achieving pseudoaccommodation in phakic eyes and pseudophakic eyes. However, in our study there was not an increase in coma in eyes with the EDOF IOL compared with eyes with the aspheric monofocal IOL. The spherical aberration modification induced by the Mini Well IOL in the central 3.0 mm zone is much higher than that of normal cornea in the same area; therefore, the IOL is expected to provide good vision regardless the corneal spherical aberrations. A recent study of optical bench results after simulated corneal refractive surgery26 also indicated that the refractive and aberrometric results with EDOF IOLs, and with the Mini Well IOL in particular, would be good after laser in situ keratomileusis for myopia or hyperopia. The Strehl ratio showed that the optical quality at the 4.0 mm aperture diameter was higher than that of spherical IOLs but lower than that of a hyperaspheric IOL as reported in the literature.22 At the time of our study, no other data on objective in vivo optical quality were available for the Mini Well IOL. Using an optical bench, DomínguezVicent et al.13 compared the optical quality of 2 trifocal IOLs. They found that the Mini Well IOL showed a smoother transition of the modulation transfer function (MTF) curve at a 3.0 mm aperture diameter, a better MTF at 2.5 D of defocus, and a lower MTF at 3.5 D defocus.13 At 3.5 D of defocus, the difference between the trifocal IOLs and the EDOF IOL increased as the aperture diameter increased. In another in vitro study,14 the same group compared the Mini Well IOL with the Tecnis Symfony IOL (Johnson & Johnson) and Mplus IOL (Oculentis GmbH). The optical quality of the IOLs was described by the MTF at the best focus and from 1.5 D to 3.0 D of defocus with different pupil diameters. With a 3.0 mm pupil diameter, the 3 IOLs had similar MTF curves for distance; however, the Mini Well IOL had a wider MTF curve (and thus lower MTF levels) for near vision.14 As the pupil diameter increased, the Mini Well IOL provided better distance vision than the Tecnis Symfony and Mplus IOLs, while the difference in near vision was maintained. We conclude that on an optical bench, the EDOF Mini Well IOL behaves like a refractive apodized IOL. Optical apodization also accounts for the low photic disturbances reported by the patients. The lack of diffractive rings explains the lack of reported starburst, and the greater depth of focus is probably the reason there were few reports of little halo. No patient in our study reported problems driving at night. In conclusion, the new EDOF Mini Well IOL increased the depth of focus over that provided by the aspheric monofocal Mini IOL. A CDVA of 0.1 logMAR was maintained across 2.0 D dioptric intervals with no increase in the overall ocular aberration and with minimal photic phenomena. Further comparisons of the new IOL with other EDOF IOLs and multifocal IOLs in clinical practice and a more detailed study of the aberrations from the pericentral zone are needed.
925
WHAT WAS KNOWN The new extended depth-of-focus intraocular lens (EDOF IOL) is based on alternating positive and negative spherical aberration in the central 3.0 mm optic. Greater depth of focus has been shown in experimental and clinical studies compared with other EDOF IOLs and multifocal IOLs.
WHAT THIS PAPER ADDS The new EDOF IOL provided 2.0 diopters (D) of pseudoaccommodation versus the 1.0 D provided by the monofocal aspheric IOL with the same platform. Central positive and negative spherical aberration compensated for each other, providing the same aberration profile as that provided by the monofocal IOL. The subjective and objective optical qualities were the same with the 2 IOL types, with minimal halo and no starburst.
REFERENCES 1. Bellucci R. Multifocal intraocular lenses. Curr Opin Ophthalmol 2005; 16:33–37 2. Gatinel D, Pagnoulle C, Houbrechts Y, Gobin L. Design and qualification of a diffractive trifocal optical profile for intraocular lenses. J Cataract Refract Surg 2011; 37:2060–2067 rnandez-Buenaga R, Pikkel J, Maldonado M. 3. Alio JL, Plaza-Puche AB, Fe Multifocal intraocular lenses: an overview. Surv Ophthalmol 2017; 62:611–634 ~oz G, Albarra n-Diego C, Cervin ~o A, Ferrer-Blasco T, García-Lazaro S. 4. Mun Visual and optical performance with the ReZoom multifocal intraocular lens. Eur J Ophthalmol 2012; 22:356–362 ~oz G, Albarran-Diego C, Ferrer-Blasco T, Sakla HF, García5. Mun zaro S. Visual function after bilateral implantation of a new zonal La refractive aspheric multifocal intraocular lens. J Cataract Refract Surg 2011; 37:2043–2052 6. Venter JA, Pelouskova M, Collins BM, Schallhorn SC, Hannan SJ. Visual outcomes and patient satisfaction in 9366 eyes using a refractive segmented multifocal intraocular lens. J Cataract Refract Surg 2013; 39:1477–1484 7. Cumming JS, Colvard DM, Dell SJ, Doane J, Fine IH, Hoffman RS, Packer M, Slade SG. Clinical evaluation of the Crystalens AT-45 accommodating intraocular lens; results of the U.S. Food and Drug Administration clinical trial. J Cataract Refract Surg 2006; 32:812–825 8. Zamora-Alejo KV, Moore SP, Parker DGA, Ullrich K, Esterman A, Goggin M. Objective accommodation measurement of the Crystalens HD compared to monofocal intraocular lenses. J Refract Surg 2013; 29:133–139 S, Jaroszewicz Z, Kolodziejczyk A. Visual Strehl perfor9. Gallego AA, Bara mance of IOL designs with extended depth of focus. Optom Vis Sci 2012; 89:1702–1707 10. Rocha KM. Extended depth of focus IOLs: the next chapter in refractive technology?. [guest editorial]. J Refract Surg 2017; 33:146–149 11. Breyer DRH, Kaymak H, Ax T, Kretz FTA, Auffarth GU, Hagen PR. Multifocal intraocular lenses and extended depth of focus intraocular lenses. Asia Pac J Ophthalmol 2017; 6:339–349 12. Bellucci R, Curatolo MC. A new extended depth of focus intraocular lens nased on spherical aberration. J Refract Surg 2017; 33:389–394 13. Domínguez-Vicent A, Esteve-Taboada JJ, Del Aguila-Carrasco AJ, Monlvez-Romin D, Monte s-Mico R. In vitro optical quality comparison of 2 sa trifocal intraocular lenses and 1 progressive multifocal intraocular lens. J Cataract Refract Surg 2016; 42:138–147 AJ, Ferrer14. Domínguez-Vicent A, Esteve-Taboada JJ, Del Aguila-Carrasco R. In vitro optical quality comparison between the Blasco T, Montes-Mico Mini WELL Ready progressive multifocal and the TECNIS Symfony. Graefes Arch Clin Exp Ophthalmol 2016; 254:1387–1397 15. Savini G, Schiano-Lomoriello D, Balducci N, Barboni P. Visual performance of a new extended depth-of-focus intraocular lens compared to a distancedominant diffractive multifocal intraocular lens. J Refract Surg 2018; 34:228–235 16. Bregnhøj JF, Mataji P, Næser K. Refractive, anterior corneal and internal astigmatism in the pseudophakic eye. Acta Ophthalmol 2015; 93:33–40
Volume 45 Issue 7 July 2019
926
DEPTH OF FOCUS IN CATARACT PATIENTS WITH EDOF IOL
17. Wolffsohn JS, Jinabhai AN, Kingsnorth A, Sheppard AL, Naroo SA, Shah S, Buckhurst P, Hall LA, Young G. Exploring the optimum step size for defocus curves. J Cataract Refract Surg 2013; 39:873–880 18. Malandrini A, Martone G, Menabuoni L, Catanese AM, Tosi GM, Balestrazzi A, Corsani C, Fantozzi M. Bifocal refractive corneal inlay implantation to improve near vision in emmetropic presbyopic patients. J Cataract Refract Surg 2015; 41:1962–1972 19. Chang DH, Rocha KM. Intraocular lens optics and aberrations. Curr Opin Ophthalmol 2016; 27:298–303 20. Peng C, Zhao J, Ma L, Qu B, Sun Q, Zhang J. Optical performance after bilateral implantation of apodized aspheric diffractive multifocal intraocular lenses with C3.00-D addition power. Acta Ophthalmol 2012; 90:e586– e593 21. Salmon TO, van de Pol C. Normal-eye Zernike coefficients and root-meansquare wavefront errors. J Cataract Refract Surg 2006; 32:2064–2074 22. Bellucci R, Morselli S, Pucci V. Spherical aberration and coma with an aspherical and a spherical intraocular lens in normal age-matched eyes. J Cataract Refract Surg 2007; 33:203–209 ~ero DP, de Fez D, Caballero MT, Miret JJ. In vitro 23. Camps VJ, Tolosa A, Pin aberrometric assessment of a multifocal intraocular lens and two extended depth of focus IOLs. J Ophthalmol 2017 article ID7095734 n E, Mirabet S, Yago I, Marín JM, Artal P. Extended depth of 24. Villegas EA, Alco focus with induced spherical aberration in light-adjustable intraocular lenses. Am J Ophthalmol 2014; 157:142–149 s-Mico R, Iskander DR. The effect 25. del Aguila-Carrasco AJ, Read SA, Monte of aberrations on objectively assessed image quality and depth of focus. J Vis 2017; 17 (2)
Volume 45 Issue 7 July 2019
~ero DP. Simulation of the effect 26. Camps VJ, Miret JJ, García C, Tolosa A, Pin of different presbyopia-correcting intraocular lenses with eyes with previous laser refractive surgery. J Refract Surg 2018; 34:222–227 OTHER CITED MATERIAL A. Barrett GD. Barrett Universal II Formula. Singapore, Asia-Pacific Association of Cataract and Refractive Surgeons. Available at: http://www.apacrs.org /barrett_universal2/. Accessed April 1, 2019 B. Kramer R, Wessels HA, Schyns MWRJ. Halo and glare simulation test. Available at: http://www.mediawebtool.com/practicetools/drkramer_roosen daal/halo--glare-simulatie/index.html. Accessed April 1, 2019
Disclosures: Dr. R. Bellucci was a consultant to Sifitech. None of the other authors has a financial or proprietary interest in any material or methods mentioned.
First author: Roberto Bellucci, MD University Hospital of Verona, Italy
ARTICLE
Clinical and aberrometric evaluation of a new extended depth-of-focus intraocular lens based on spherical aberration Roberto Bellucci, MD, Miriam Cargnoni, OD, Carlo Bellucci, MD
Purpose: To compare the refractive, visual, and aberrometric results with a new extended depth-of-focus intraocular lens (EDOF IOL) based on alternating positive and negative spherical aberration in the central 3.0 mm optical zone and an aspheric monofocal IOL of the same platform. Setting: Ophthalmology, University Hospital of Verona, Italy. Design: Prospective case series. Methods: Cataract patients free from other ocular disease had bilateral implantation of the EDOF Mini Well IOL or the monofocal Mini IOL. Four to 6 weeks after second-eye surgery, the refraction, visual acuity, defocus curve, contrast sensitivity, and photic symptoms were assessed. Wavefront analysis was performed. The primary endpoint of was the amplitude of the dioptric interval for 0.1 logarithm of the minimum angle of
T
he quest for presbyopia correction with intraocular lenses (IOLs) has led to several solutions based on different optical approaches. Diffraction-based multifocal IOLs have been available in Europe since 1988, and there have been continuous improvements in several aspects of IOL optics and manufacturing.1–3 Refraction-based multifocal IOLs have also been studied extensively and used in clinical practice, with the zonal near addition as the most popular design at present.4–6 Pseudoaccommodating IOLs with some form of mobile or deformable optics have been used in a clinical setting; however, the clinical results have been inconsistent.7,8 More recently, IOLs based on extending the depth of focus have received attention, with the goal of obtaining seamless distance and near vision across a dioptric interval.9–11 A lower near addition, the correction of chromatic aberration, a selected change in spherical aberration, and a
resolution (logMAR) visual acuity. The secondary endpoint was an aberration comparison between the two IOLs.
Results: The study comprised two groups of 25 patients each. The corrected distance visual acuity was better with the monofocal IOL by 0.02 logMAR (P Z .03). The 0.1 logMAR dioptric interval was 2.0 diopters (D) for the EDOF IOL and 1.0 D for the monofocal IOL (P < .001). The mean CDVA at 2.0 defocus was 0.15 logMAR G 0.08 (SD) and 0.52 G 0.14 logMAR, respectively (P < .001). There was no difference in contrast sensitivity or photic symptoms. The optical aberrations at 4.0 mm and 6.0 mm aperture diameters were similar in the two groups.
Conclusion: The EDOF IOL based on spherical aberration provided greater depth of focus than the aspheric monofocal IOL without increasing optical aberrations and with few photic symptoms. J Cataract Refract Surg 2019; 45:919–926 Q 2019 ASCRS and ESCRS
combination have been adopted by IOL designers and manufacturers.9–11 The design of the new Mini Well IOL (SIFI) is based on changes in spherical aberration over the 3.0 mm central IOL surface.12 Optical bench studies indicate good depth of focus with a light-distribution profile different from that of other multifocal IOLs and extended depth-of-focus (EDOF) IOLs.13,14 Early clinical results confirmed that the new IOL provides greater depth of focus and good visual performance compared with a diffractive multifocal IOL.15 However, to our knowledge, a comprehensive study comparing the results of the Mini Well EDOF IOL and the aspheric monofocal Mini IOL (SIFI) in patients has not been published. The present study assessed the refractive, visual, and aberrometric results in two groups of patients who had bilateral implantation of the EDOF Mini Well IOL or the monofocal Mini IOL.
Submitted: September 4, 2018 | Final revision submitted: January 7, 2019 | Accepted: February 9, 2019 From the University Hospital of Verona (R. Bellucci, Cargnoni) and the University Hospital of Parma (C. Bellucci), Italy. Supported in part by SIFI, Catania, Italy. Corresponding author: Roberto Bellucci, MD, Via degli Abeti 17, Salo, Italy 25087. Email: [email protected]. Q 2019 ASCRS and ESCRS Published by Elsevier Inc.
0886-3350/$ - see frontmatter https://doi.org/10.1016/j.jcrs.2019.02.023
920
DEPTH OF FOCUS IN CATARACT PATIENTS WITH EDOF IOL
PATIENTS AND METHODS This prospective study comprised patients scheduled for bilateral cataract surgery who were free from ocular or general disease that could affect the anatomic and visual results of surgery and who had axial lengths between 22.0 mm and 26.5 mm. All patients gave informed consent to participate in the study, to receive the EDOF IOL or the monofocal IOL in both eyes according to a randomization process, and to have a postoperative examination. The study followed the tenets of the Declaration of Helsinki and was approved by the local regulative committee. Inclusion criteria were anterior corneal astigmatism on corneal topography (Sirius, Costruzione Strumenti Oftalmici) of less than 1.00 diopter (D) if with the rule (WTR) or 0.25 D if against the rule to limit the effect of posterior corneal astigmatism on postoperative refraction16 and a photopic pupil diameter on automated refraction (RK-F2, Canon, Inc.) larger than 2.0 mm. Exclusion criteria (enforced after patient enrollment) were second-eye surgery cancelled or deferred, surgical complications preventing secure in-the-bag IOL implantation in either eye, and inability to complete the follow-up program. Patients, with the exception of dropout replacements, were assigned on an alternative basis to the EDOF IOL or the monofocal IOL at the time of first-eye surgery. The axial length was measured with the Lenstar optical biometer (Haag-Streit AG). The Barrett Universal II formulaA was used to determine the IOL power, with the A constant set at 118.8 for both IOL types. Intraocular Lenses The Mini Well EDOF IOL and the Mini IOL share the same platform as follows: 25% hydrophilic acrylic, biconvex 6.0 mm optics, 4 fenestrated haptics with 5-degree angulation, posterior and anterior square-edged optics, and 10.75 mm overall length. They can be implanted through an incision smaller than 2.0 mm. The Mini IOL optic is monofocal and aspheric with 0.14 mm of negative spherical aberration at a 5.0 mm aperture diameter. The Mini Well IOL optic incorporates 2 spherical aberration profiles in the central 3.00 mm zone, a central 1.95 mm diameter zone with positive spherical aberration and a pericentral 1.05 mm wide annulus with a negative spherical aberration (Figure 1). The concept is that the combination of the 2 profiles will extend the depth of focus, providing a smooth transition between zones and a gradual power shift to support progressive vision.12 The optical design of the IOL is barely detectable on normal slitlamp observation, and the IOL looks like a monofocal IOL. Surgical Technique All surgeries were performed by the same surgeon (R.B.) using topical anesthesia. Phacoemulsification was performed with the Stellaris system (Bausch & Lomb, Inc.) through a 2.0 mm incision. The 2.0 mm incision was located on the vertical meridian when the posterior corneal with-the-rule astigmatism was 0.5 D to 1.0 D and
Figure 1. Surgical image of the new extended depth-of-focus intraocular lens.
Volume 45 Issue 7 July 2019
on the horizontal meridian in the other cases. The IOL was implanted with a 1.8 mm injector (Medicel AG). For 15 days after surgery, patients received bromfenac 0.09% eyedrops 2 times a day and a combination of tobramycin 0.3% and dexamethasone 1.0% eyedrops 4 times a day. Second-eye surgery was performed 21 to 28 days after first-eye surgery. Postoperative Evaluation Measurements were taken 4 to 6 weeks after second-eye surgery by personnel unaware which IOL was implanted. After slitlamp observation, automated refraction at a 2.2 mm aperture diameter and the photopic pupil diameter were measured using the same automated refractor as preoperatively. Monocular and binocular uncorrected (UDVA) and corrected (CDVA) distance visual acuities were measured at 4 m using the Early Treatment Diabetic Retinopathy Study chart. To achieve pseudoaccommodation, the optical correction for distance was optimized with the red–green test. Uncorrected (UIVA) and distance-corrected (DCIVA) intermediate visual acuities were measured at 60 cm and uncorrected (UNVA) and distance-corrected (DCNVA) near visual acuities at 40 cm using optotypes (Precision Vision). Defocus curves were obtained with binocular vision by randomly adding plus lenses (up to C2.0 D) and minus lenses (up to 4.0 D) in 0.5 D steps17 to the distance optical correction and then recording the visual acuity with each lens power. Contrast sensitivity was measured for distance with binocular vision and with the full optical correction in place. The computer-displayed vision chart (Costruzione Strumenti Oftalmici) presents sine-wave gratings at 1.5, 3.0, 6.0, 12.0, and 18.0 cycles per degree (cpd) with a background luminance of 85 candelas/m2.18 The mean of the log10 values for each spatial frequency was used for comparison. Optical aberrations were assessed with the KR-1D device (Topcon Corp.). This device combines Placido-disk corneal topography with Hartmann-Shack ocular aberrometry and provides the internal aberration as the difference between the 2 measurements. Because of the low influence of the posterior corneal surface on higher-order aberrations (HOAs), internal HOAs are considered to be mainly caused by the IOL.19 Evaluated were total HOAs and the following Zernike (Z) coefficients: Z3( 3,C3), which represents coma-like aberration; Z3( 1,C1), which represents coma aberration; Z4( 4,C4), which represents sphericallike aberration; and Z4(0), which represents spherical aberration. Measurements were taken in mydriasis for 4.0 mm and 6.0 mm aperture diameters. In addition, the wavefront spherical equivalent refractions at 4.0 mm and at 6.0 mm were compared. The point-spread function derived from the optical HOAs and expressed as the Strehl ratio was taken as an objective indicator of the postoperative optical quality of the eyes. The device used in the study provides point-spread function data at a 4.0 mm aperture diameter only. The subjective optical quality was assessed using a questionnaire that asked patients whether they had any of the following visual disturbances at night: glare, halos, starbursts, hazy vision, monocular polyopia, simultaneous vision, and defocus. An online test described by Kramer et al.B was adopted to evaluate the results. In this test, 3 types of halo are shown and evaluated for size and intensity as follows: type 1, disk shaped; type 2, disk shaped with starburst; type 3, ring shaped. Statistical Analysis The primary endpoint of this study was the assessment of the dioptric intervals through which the visual acuities of 0.1 logarithm of the minimum angle of resolution (logMAR) and 0.2 logMAR were maintained in binocular vision. The visual acuity at 2.0 D minus defocus (50 cm distance) was used when calculating the minimum significant sample size, with a 0.2 logMAR difference between the monofocal group and EDOF group arbitrarily selected as clinically significant. An a error of 1.0% and a b error
921
DEPTH OF FOCUS IN CATARACT PATIENTS WITH EDOF IOL
of 95.0% were adopted. Considering 0.4 logMAR G 0.1 (SD) as the mean visual acuity at 2.0 D defocus with monofocal IOLs and 0.1 logMAR as the standard error of defocus curves,17,20 a minimum of 9 patients per group was required. The secondary endpoint was the difference in optical aberrations between the two IOL groups. Of the two aperture diameters available on the aberrometer (4.0 mm and 6.0 mm), the 4.0 mm diameter was selected for sample-size calculation because it is closest to the aberration change zone of the EDOF IOL. Aberration data for monofocal IOLs and clinically significant differences were taken from the literature.19,21,22 Table 1 shows the samplesize calculation. Based on this calculation, patients were recruited until 25 patients per group were available for analysis. The 1sample Kolmogorov-Smirnov test was used to determine whether the data were normally distributed. If the data followed a normal distribution, parametric analysis was performed and if not, nonparametric statistical analysis was used.
RESULTS This study recruited 57 patients, 28 in the EDOF group and 29 in the monofocal group. Two patients in the EDOF group and 3 in the monofocal group were excluded after first-eye surgery because of health problems that required deferment of second-eye surgery. An additional 2 patients (1 per group) were unable to complete the follow-up examination and were also excluded. Thus, the analysis included 25 patients in each group (P Z 1.000), with 6 women and 19 men in the EDOF group and 9 women and 16 men in the monofocal group (P Z .538). Table 2 shows the patients’ characteristics. Surgery was uneventful in all eyes. The mean IOL power was 22.30 G 2.40 D in the EDOF group and 22.16 G 2.27 D in the monofocal group (P O .1). Refraction and Visual Acuity
Table 3 shows the postoperative automated refraction and clinical refraction assessed with the duochrome test. In the EDOF group the automated refraction (2.2 mm aperture diameter) was more myopic than the clinical refraction by 0.33 D. The postoperative photopic pupil diameter was slightly narrower than preoperatively in both IOL groups (P ! .05). Table 4 shows the visual acuity results. The binocular UDVA and monocular CDVA were slightly better in the monofocal group; the difference of 0.02 to 0.03 logMAR was statistically significant (P ! .05). The intermediate and the near visual acuities were statistically significantly
Table 1. Sample-size calculation for the aberration study at 4.0 mm aperture diameter assuming an a error of 0.01 and a b error of 0.05. Parameter HOA Sphere Z4( 4,C4) Coma Z3( 3,C3) SA Z4(0)
Mean (mm) ± SEM*
P Value
Eyes (n)
0.15 G 0.06 0.05 G 0.03 0.13 G 0.07 0.03 G 0.02
.05 .05 .07 .07
50 26 36 9
HOA Z higher-order aberrations; SA Z spherical aberration; Z Z Zernike *Monofocal
better in the EDOF group, with large between-group differences in the logMAR values. Figure 2 shows the defocus curves obtained with binocular vision. All between-group differences from 1.00 D defocus to 2.50 D defocus were statistically significant. A binocular CDVA of 0.10 logMAR or better was maintained between C0.50 D and 1.50 D of defocus in the EDOF group and between C0.50 D and 0.50 D in the monofocal group. A binocular CDVA of 0.2 logMAR or better was maintained between C1.00 D and 2.00 D of defocus and between C1.00 D and 1.00 D of defocus, respectively. For 2.00 D defocus, visual acuity was 0.15 G 0.08 logMAR in the EDOF group and was 0.52 G 0.14 logMAR in the monofocal group; the difference of 0.37 logMAR exceeded the 0.20 logMAR level considered as clinically significant. The difference in visual acuity between the EDOF group and the monofocal group was statistically significant from 0.50 D to 4.00 D of defocus. Figure 3 shows the binocular contrast sensitivity data. The overall level of the measured contrast sensitivity was as expected in patients of this age. It was slightly lower in the EDOF IOL group. The only statistically significant between-group difference was at 18 cpd (P Z .01). Aberration Data
Figure 4 shows the total ocular, corneal, and internal aberrations measured at 4.0 mm and at 6.0 mm aperture diameters. At a 4.0 mm aperture diameter, the values of total HOAs, total coma, and total sphere were in the normal range for pseudophakic eyes. The spherical aberration Z4(0) was slightly negative in both groups; the monofocal IOL induced less negative spherical aberration than the 0.14 mm (at 5.0 mm aperture diameter) reported by the manufacturer. The only the statistically significant difference was in the total HOAs and total coma, with the values being better in the EDOF group. The aberrations at a 6.0 mm aperture diameter were approximately 4-fold the aberrations at a 4.0 mm aperture diameter. There were no statistically significant differences between the IOL groups. The EDOF group had lower ocular and internal aberrations than the monofocal IOL at 4.0 mm. However, the ocular and internal aberrations at 6.0 mm were lower in the monofocal group. Both IOLs induced some positive spherical aberration at 6.0 mm. Thus, the 6.0 mm wavefront refraction was more myopic than the 4.0 mm wavefront refraction by a mean of 0.61 G 0.32 D in the EDOF group and 0.66 G 0.67 D in the monofocal group (P O .1). Objective and Subjective Optical Quality
The mean optical quality at a 4.0 mm aperture diameter, assessed using the Strehl ratio, was 0.205 G 0.112 in the EDOF group and 0.167 G 0.138 in the monofocal group (P O .1). The difference between the two groups was not statistically significant and reflects the difference in the HOAs shown in Figure 4. The aberrometer software did not provide Strehl ratio values for the 6.0 mm aperture diameter. Volume 45 Issue 7 July 2019
922
DEPTH OF FOCUS IN CATARACT PATIENTS WITH EDOF IOL
Table 2. Patient characteristics. Mean ± SD Parameter Age (y) Axial length (mm) Flat K (D) Steep K (D) Pupil diameter (mm) ACD (mm) CDVA (LogMAR) SE (D) Astigmatism (D)
EDOF IOL
Monofocal IOL
P Value
76 G 7 23.27 G 0.92 44.05 G 1.18 44.68 G 1.16 3.02 G 0.44 3.08 G 0.39 0.52 G 0.27 0.81 G 2.34 0.53 G 0.29
78 G 9 23.41 G 1.01 44.12 G 1.15 44.59 G 1.16 3.10 G 0.49 3.11 G 0.40 0.46 G 0.22 0.72 G 1.89 0.59 G 0.31
.877 .470 .764 .699 .392 .705 .226 .833 .320
ACD Z anterior chamber depth; CDVA Z corrected distance visual acuity; EDOF Z extended depth of focus; IOL Z intraocular lens; K Z keratometry; logMAR Z logarithm of the minimum angle of resolution; SE Z spherical equivalent
On the questionnaire, 7 patients (28%) in the EDOF group and 3 patients (12%) in the monofocal group reported a low degree of photic symptoms at night that did not affect driving. Regarding the images in the online test, all patients reported type 1 halo (disk shaped with no starburst), the size of which was 20% of the test scale. In the EDOF group, 4 patients (16%) reported 20% intensity and 3 patients (12%) reported 40% intensity. In the monofocal group, 2 patients (8%) reported 20% intensity and 1 patient (4%) reported 40% intensity. The difference between the two groups was not statistically significant according to the Fisher exact test. DISCUSSION The new EDOF Mini Well IOL design incorporates a modification of spherical aberration in the central optical zone, the purpose of which is to increase the depth of focus.12 In the present study, the new IOL was compared with the aspheric monofocal Mini IOL, which has the same platform. We assessed whether the new EDOF IOL design provides better optical and visual outcomes. We did not consider the corneal aberration profile during recruitment
so we could assess the ability of this IOL to provide an EDOF in unselected patients. The aberration change of the Mini Well IOL takes place in the central 3.0 mm zone and the positive spherical aberration in the central 1.95 mm zone; therefore, we were not surprised to find that the automated refraction at a 2.2 mm aperture diameter was more myopic than the clinical refraction, for which the aperture diameter is larger and the same as the pupil diameter. However, the eye is not a centered optical system; thus, evaluation of the mathematic calculation of this difference (0.33 D; P Z .071) should be done with caution. In our study, the postoperative binocular UDVA and monocular CDVA were worse in the EDOF group than in the monofocal group. However, the between-group difference in binocular CDVA was not statistically significant. The intermediate and near acuities were better in the EDOF IOL group, with DCIVA and DCNVA slightly worse than the UIVA and UNVA because of the small myopic refractive outcome. Binocularly, the DCIVA and DCNVA were statistically significantly better in the EDOF group, with a difference between the two groups of 0.32 logMAR and
Table 3. Postoperative refraction. Parameter Automated SE (D) Mean G SD Range Refractive SE (D) Mean G SD Range Automated cylinder (D) Mean G SD Range Refractive cylinder (D) Mean G SD Range Photopic pupil diameter (mm) Mean G SD
EDOF IOL
Monofocal IOL
P Value
0.59 G 0.58 0.50, 2.25
0.18 G 0.64 0.75, 1.50
.001
0.26 G 0.62 0.50, 1.50
0.20 G 0.61 0.75, 1.50
.627
0.69 G 0.37 0.00, 1.50
0.76 G 0.44 0.00, 1.75
.391
0.74 G 0.41 0.00, 1.00
0.68 G 0.47 0.00, 1.25
.498
2.83 G 0.44
2.90 G 0.46
.439
EDOF Z extended depth of focus; IOL Z intraocular lens; SE Z spherical equivalent
Volume 45 Issue 7 July 2019
923
DEPTH OF FOCUS IN CATARACT PATIENTS WITH EDOF IOL
Table 4. Postoperative visual acuity (logMAR) by group. Parameter Monocular UDVA Mean G SD Range Binocular UDVA Mean G SD Range Monocular CDVA Mean G SD Range Binocular CDVA Mean G SD Range Monocular UIVA 60 cm Mean G SD Range Monocular DCIVA 60 cm Mean G SD Range Binocular DCIVA 60 cm Mean G SD Range Monocular UNVA 40 cm Mean G SD Range Monocular DCNVA 40 cm Mean G SD Range Binocular DCNVA 40 cm Mean G SD Range
Monofocal IOL
P Value
0.16 G 0.14 0.58, 0.00
0.12 G 0.10 0.52, 0.02
.103
0.07 G 0.06 0.14, 0.00
0.04 G 0.04 0.12, 0.02
.043
0.04 G 0.05 0.14, 0.04
0.02 G 0.04 0.12, 0.06
.030
0.02 G 0.04 0.04, 0.06
0.06 G 0.04 0.04, 0.08
.084
0.16 G 0.14 0.32, 0.08
0.46 G 0.12 0.70, 0.28
!.001
0.18 G 0.08 0.28, 0.06
0.52 G 0.18 0.76, 0.30
!.001
0.16 G 0.06 0.24, 0.04
0.48 G 0.13 0.68, 0.28
!.001
0.22 G 0.12 0.34, 0.08
0.64 G 0.20 0.62, 0.24
!.01
0.24 G 0.06 0.24, 0.08
0.68 G 0.11 0.84, 0.36
!.01
0.22 G 0.08 0.16, 0.06
0.64 G 0.12 0.78, 0.32
!.01
EDOF IOL
CDVA Z corrected distance visual acuity; DCIVA Z distance-corrected intermediate visual acuity; DCNVA Z distance-corrected near visual acuity; EDOF Z extended depth of focus; IOL Z intraocular lens; K Z keratometry; logMAR Z logarithm of the minimum angle of resolution; UDVA Z uncorrected distance visual acuity; UIVA Z uncorrected intermediate visual acuity; UNVA Z uncorrected near visual acuity
0.44 logMAR, respectively; these values exceed the 0.2 logMAR level we set for clinical significance. The binocular defocus curve showed similar results, with the curve of the EDOF IOL higher than that of the monofocal IOL by 0.086 logMAR ( 1.0 D defocus), 0.37 logMAR ( 2.0 D
Figure 2. Defocus curve obtained binocularly with the distance correction in place (EDOF Z extended depth of focus; logMAR Z logarithm of the minimum angle of resolution; visual acuity Z corrected distance visual acuity).
defocus), and 0.45 logMAR ( 3.0 D defocus). The focal interval in which selected logMAR visual acuities were maintained was different between the two IOL groups; the interval for 0.1 logMAR and for 0.2 logMAR in the EDOF group was 1.0 D larger than in the monofocal IOL group. Savini et al.15 found the same intervals monocularly in
Figure 3. Binocular contrast sensitivity (*P Z .01; EDOF Z extended depth of focus; logCS Z log contrast sensitivity).
Volume 45 Issue 7 July 2019
924
DEPTH OF FOCUS IN CATARACT PATIENTS WITH EDOF IOL
Figure 4. Higher-order aberrations at 4.0 mm and 6.0 mm aperture diameter (EDOF Z extended depth of focus; HOAs Z total higher-order aberrations; RMS Z root mean square; SPH Z sphere).
20 patients who had implantation of the Mini Well IOL. The intervals compared favorably with those of a diffractive multifocal IOL. Savini et al. also studied the reading speed and concluded that the EDOF Mini Well IOL provided equal visual efficiency for distance and for near but performed better at intermediate distance.15 The contrast sensitivity data in our study are consistent with the age of our patients. Although contrast sensitivity was slightly better with the monofocal IOL, the only statistically significant between-group difference was at 18 cpd. The contrast sensitivity levels were low in our study and lower than those measured by Savini et al.15 This might be because our patients were older and the examination conditions in our study were different than those of Savini et al. We studied optical aberrations to determine the effect of the EDOF Mini Well IOL on the postoperative aberration profile in patients’ eyes. At a 4.0 mm aperture diameter, the values of total HOAs, total coma, and total sphere were in the normal range for pseudophakic eyes.19,22 However, the EDOF group had lower ocular and internal aberrations than the monofocal group at 4.0 mm. At 6.0 mm, the ocular and internal aberrations were lower in the monofocal group, although the differences were not statistically significant. Therefore, we did not find an increase in optical aberrations with the EDOF IOL compared with the aspheric monofocal IOL and the EDOF IOL did not
Volume 45 Issue 7 July 2019
increase the optical aberrations of the whole eye at 4.0 mm or 6.0 mm. The compensation for the positive central spherical aberration by the negative pericentral spherical aberration is the probable reason for this finding. To study the central differences, an aberrometer providing 2.0 mm, 2.5 mm, and 3.0 mm data should be used; such a device was not available for this study. To our knowledge, no other in vivo study has assessed optical aberrations in eyes with the EDOF Mini Well IOL. Camps et al.23 studied aberrations in vitro using an optical bench. They compared the EDOF Mini Well IOL with another EDOF IOL and a refractive multifocal IOL. Eyes with the Mini Well IOL had no 3rd-order aberration, 0.13 mm negative 4th-order aberration, or C0.12 mm positive 6th-order spherical aberration at a 3.0 mm aperture diameter. Both types of spherical aberration decreased as the aperture diameter increased.23 Camps et al. confirmed that the EDOF Mini Well IOL is based on a variation in spherical aberration, and our study shows the clinical impact of this variation. The low amount of negative spherical aberration required to extend the depth of focus was confirmed by Villegas et al.24 They induced negative spherical aberration in the nondominant eye of 17 patients who had bilateral implantation of a light-adjustable IOL and found 0.083 G 0.020 mm at a 4.0 mm aperture diameter was sufficient for reading.24 Their study also showed that both positive aberration and negative spherical aberration
DEPTH OF FOCUS IN CATARACT PATIENTS WITH EDOF IOL
can be used to extend the depth of focus. In a recent paper, Aguila-Carrasco et al.25 highlighted the importance of coma in achieving pseudoaccommodation in phakic eyes and pseudophakic eyes. However, in our study there was not an increase in coma in eyes with the EDOF IOL compared with eyes with the aspheric monofocal IOL. The spherical aberration modification induced by the Mini Well IOL in the central 3.0 mm zone is much higher than that of normal cornea in the same area; therefore, the IOL is expected to provide good vision regardless the corneal spherical aberrations. A recent study of optical bench results after simulated corneal refractive surgery26 also indicated that the refractive and aberrometric results with EDOF IOLs, and with the Mini Well IOL in particular, would be good after laser in situ keratomileusis for myopia or hyperopia. The Strehl ratio showed that the optical quality at the 4.0 mm aperture diameter was higher than that of spherical IOLs but lower than that of a hyperaspheric IOL as reported in the literature.22 At the time of our study, no other data on objective in vivo optical quality were available for the Mini Well IOL. Using an optical bench, DomínguezVicent et al.13 compared the optical quality of 2 trifocal IOLs. They found that the Mini Well IOL showed a smoother transition of the modulation transfer function (MTF) curve at a 3.0 mm aperture diameter, a better MTF at 2.5 D of defocus, and a lower MTF at 3.5 D defocus.13 At 3.5 D of defocus, the difference between the trifocal IOLs and the EDOF IOL increased as the aperture diameter increased. In another in vitro study,14 the same group compared the Mini Well IOL with the Tecnis Symfony IOL (Johnson & Johnson) and Mplus IOL (Oculentis GmbH). The optical quality of the IOLs was described by the MTF at the best focus and from 1.5 D to 3.0 D of defocus with different pupil diameters. With a 3.0 mm pupil diameter, the 3 IOLs had similar MTF curves for distance; however, the Mini Well IOL had a wider MTF curve (and thus lower MTF levels) for near vision.14 As the pupil diameter increased, the Mini Well IOL provided better distance vision than the Tecnis Symfony and Mplus IOLs, while the difference in near vision was maintained. We conclude that on an optical bench, the EDOF Mini Well IOL behaves like a refractive apodized IOL. Optical apodization also accounts for the low photic disturbances reported by the patients. The lack of diffractive rings explains the lack of reported starburst, and the greater depth of focus is probably the reason there were few reports of little halo. No patient in our study reported problems driving at night. In conclusion, the new EDOF Mini Well IOL increased the depth of focus over that provided by the aspheric monofocal Mini IOL. A CDVA of 0.1 logMAR was maintained across 2.0 D dioptric intervals with no increase in the overall ocular aberration and with minimal photic phenomena. Further comparisons of the new IOL with other EDOF IOLs and multifocal IOLs in clinical practice and a more detailed study of the aberrations from the pericentral zone are needed.
925
WHAT WAS KNOWN The new extended depth-of-focus intraocular lens (EDOF IOL) is based on alternating positive and negative spherical aberration in the central 3.0 mm optic. Greater depth of focus has been shown in experimental and clinical studies compared with other EDOF IOLs and multifocal IOLs.
WHAT THIS PAPER ADDS The new EDOF IOL provided 2.0 diopters (D) of pseudoaccommodation versus the 1.0 D provided by the monofocal aspheric IOL with the same platform. Central positive and negative spherical aberration compensated for each other, providing the same aberration profile as that provided by the monofocal IOL. The subjective and objective optical qualities were the same with the 2 IOL types, with minimal halo and no starburst.
REFERENCES 1. Bellucci R. Multifocal intraocular lenses. Curr Opin Ophthalmol 2005; 16:33–37 2. Gatinel D, Pagnoulle C, Houbrechts Y, Gobin L. Design and qualification of a diffractive trifocal optical profile for intraocular lenses. J Cataract Refract Surg 2011; 37:2060–2067 rnandez-Buenaga R, Pikkel J, Maldonado M. 3. Alio JL, Plaza-Puche AB, Fe Multifocal intraocular lenses: an overview. Surv Ophthalmol 2017; 62:611–634 ~oz G, Albarra n-Diego C, Cervin ~o A, Ferrer-Blasco T, García-Lazaro S. 4. Mun Visual and optical performance with the ReZoom multifocal intraocular lens. Eur J Ophthalmol 2012; 22:356–362 ~oz G, Albarran-Diego C, Ferrer-Blasco T, Sakla HF, García5. Mun zaro S. Visual function after bilateral implantation of a new zonal La refractive aspheric multifocal intraocular lens. J Cataract Refract Surg 2011; 37:2043–2052 6. Venter JA, Pelouskova M, Collins BM, Schallhorn SC, Hannan SJ. Visual outcomes and patient satisfaction in 9366 eyes using a refractive segmented multifocal intraocular lens. J Cataract Refract Surg 2013; 39:1477–1484 7. Cumming JS, Colvard DM, Dell SJ, Doane J, Fine IH, Hoffman RS, Packer M, Slade SG. Clinical evaluation of the Crystalens AT-45 accommodating intraocular lens; results of the U.S. Food and Drug Administration clinical trial. J Cataract Refract Surg 2006; 32:812–825 8. Zamora-Alejo KV, Moore SP, Parker DGA, Ullrich K, Esterman A, Goggin M. Objective accommodation measurement of the Crystalens HD compared to monofocal intraocular lenses. J Refract Surg 2013; 29:133–139 S, Jaroszewicz Z, Kolodziejczyk A. Visual Strehl perfor9. Gallego AA, Bara mance of IOL designs with extended depth of focus. Optom Vis Sci 2012; 89:1702–1707 10. Rocha KM. Extended depth of focus IOLs: the next chapter in refractive technology?. [guest editorial]. J Refract Surg 2017; 33:146–149 11. Breyer DRH, Kaymak H, Ax T, Kretz FTA, Auffarth GU, Hagen PR. Multifocal intraocular lenses and extended depth of focus intraocular lenses. Asia Pac J Ophthalmol 2017; 6:339–349 12. Bellucci R, Curatolo MC. A new extended depth of focus intraocular lens nased on spherical aberration. J Refract Surg 2017; 33:389–394 13. Domínguez-Vicent A, Esteve-Taboada JJ, Del Aguila-Carrasco AJ, Monlvez-Romin D, Monte s-Mico R. In vitro optical quality comparison of 2 sa trifocal intraocular lenses and 1 progressive multifocal intraocular lens. J Cataract Refract Surg 2016; 42:138–147 AJ, Ferrer14. Domínguez-Vicent A, Esteve-Taboada JJ, Del Aguila-Carrasco R. In vitro optical quality comparison between the Blasco T, Montes-Mico Mini WELL Ready progressive multifocal and the TECNIS Symfony. Graefes Arch Clin Exp Ophthalmol 2016; 254:1387–1397 15. Savini G, Schiano-Lomoriello D, Balducci N, Barboni P. Visual performance of a new extended depth-of-focus intraocular lens compared to a distancedominant diffractive multifocal intraocular lens. J Refract Surg 2018; 34:228–235 16. Bregnhøj JF, Mataji P, Næser K. Refractive, anterior corneal and internal astigmatism in the pseudophakic eye. Acta Ophthalmol 2015; 93:33–40
Volume 45 Issue 7 July 2019
926
DEPTH OF FOCUS IN CATARACT PATIENTS WITH EDOF IOL
17. Wolffsohn JS, Jinabhai AN, Kingsnorth A, Sheppard AL, Naroo SA, Shah S, Buckhurst P, Hall LA, Young G. Exploring the optimum step size for defocus curves. J Cataract Refract Surg 2013; 39:873–880 18. Malandrini A, Martone G, Menabuoni L, Catanese AM, Tosi GM, Balestrazzi A, Corsani C, Fantozzi M. Bifocal refractive corneal inlay implantation to improve near vision in emmetropic presbyopic patients. J Cataract Refract Surg 2015; 41:1962–1972 19. Chang DH, Rocha KM. Intraocular lens optics and aberrations. Curr Opin Ophthalmol 2016; 27:298–303 20. Peng C, Zhao J, Ma L, Qu B, Sun Q, Zhang J. Optical performance after bilateral implantation of apodized aspheric diffractive multifocal intraocular lenses with C3.00-D addition power. Acta Ophthalmol 2012; 90:e586– e593 21. Salmon TO, van de Pol C. Normal-eye Zernike coefficients and root-meansquare wavefront errors. J Cataract Refract Surg 2006; 32:2064–2074 22. Bellucci R, Morselli S, Pucci V. Spherical aberration and coma with an aspherical and a spherical intraocular lens in normal age-matched eyes. J Cataract Refract Surg 2007; 33:203–209 ~ero DP, de Fez D, Caballero MT, Miret JJ. In vitro 23. Camps VJ, Tolosa A, Pin aberrometric assessment of a multifocal intraocular lens and two extended depth of focus IOLs. J Ophthalmol 2017 article ID7095734 n E, Mirabet S, Yago I, Marín JM, Artal P. Extended depth of 24. Villegas EA, Alco focus with induced spherical aberration in light-adjustable intraocular lenses. Am J Ophthalmol 2014; 157:142–149 s-Mico R, Iskander DR. The effect 25. del Aguila-Carrasco AJ, Read SA, Monte of aberrations on objectively assessed image quality and depth of focus. J Vis 2017; 17 (2)
Volume 45 Issue 7 July 2019
~ero DP. Simulation of the effect 26. Camps VJ, Miret JJ, García C, Tolosa A, Pin of different presbyopia-correcting intraocular lenses with eyes with previous laser refractive surgery. J Refract Surg 2018; 34:222–227 OTHER CITED MATERIAL A. Barrett GD. Barrett Universal II Formula. Singapore, Asia-Pacific Association of Cataract and Refractive Surgeons. Available at: http://www.apacrs.org /barrett_universal2/. Accessed April 1, 2019 B. Kramer R, Wessels HA, Schyns MWRJ. Halo and glare simulation test. Available at: http://www.mediawebtool.com/practicetools/drkramer_roosen daal/halo--glare-simulatie/index.html. Accessed April 1, 2019
Disclosures: Dr. R. Bellucci was a consultant to Sifitech. None of the other authors has a financial or proprietary interest in any material or methods mentioned.
First author: Roberto Bellucci, MD University Hospital of Verona, Italy