INTRODUCTION
Cataract surgery with monofocal intraocular lens (IOL) implantation usually achieves excellent visual results for one distance,1 2,3 4–6 7 8 9,10
Although it is usually recommended to have both eyes implanted with the same multifocal or EDOF IOLs,11,12
PATIENTS AND METHODS
The study included 2 groups of patients: group A refers to patients with a monofocal IOL (Acrysof SN60WF/SA60AT, Alcon Laboratories Inc., Fort Worth, TX) implanted in the first eye and an EDOF IOL (TECNIS Symfony, Johnson & Johnson, New Brunswick, NJ) in the second eye, and group B refers to patients implanted bilaterally with the EDOF IOL (TECNIS Symfony, Johnson & Johnson, New Brunswick, NJ). The study followed the Helsinki ethical principles and was approved by the Meir Medical Center Ethics Committee, Kfar Saba, Israel. The Meir Medical Center Ethics Committee waived informed consent from participants because data were collected retrospectively and held anonymously.
All patients underwent routine cataract surgery by phacoemulsification through a 2.4-mm clear corneal incision that was performed by a single surgeon (G.K.) for all patients at the Ein-Tal Eye Center, Tel Aviv, Israel, between January 2015 and January 2023. Medical records were retrospectively reviewed to retrieve the following information: medical and ophthalmic history, preoperative ophthalmic biomacroscopic examination, preoperative biometry using the Lenstar (LS900, Haag-Streit, Koeniz, Switzerland) and IOLMaster (IOLMaster 500/700, Carl Zeiss Meditec AG, Jena, Germany), and corneal tomography using the Pentacam (Oculus, Optikgerate GmbH, Wetzlar, Germany). All patients receiving an EDOF IOL have undergone a Pentacam corneal tomography exam assessing among other parameters the total root-mean-square values reflecting the highest total higher-order aberrations. Patients receiving a monofocal IOL did not undergo corneal tomography. The exclusion criterion for patients receiving EDOF IOLs was root-mean-square of 0.8 or above. Surgery data concerning any surgical complication and the model and power of the implanted IOL were also collected.
Contemporarily accepted IOL calculation formulas (Barrett Universal II, Haigis, Hoffer Q, Holladay-1, Olsen, and SRK/T) were used to select the IOL power and achieve emmetropia or minimal myopia. The Barrett online toric calculator13
A postoperative examination was conducted at least 3 weeks after surgery, at which manifest refraction, monocular uncorrected VA for distance (UCDVA), intermediate (UCIVA, patient’s preferred distance), and near vision (UCNVA, 16”), were evaluated in both groups, and postoperative complications were recorded. In both groups, the monocular VA data were obtained for the Symfony IOL implanted eye. The study exclusion criteria included patients with significant ophthalmic pathology, or intraoperative and/or postoperative complications that impact the patients’ visual performance and are not related to the IOL, postoperative examination less than 3 weeks postsurgery; and patients younger than 18.
A follow-up questionnaire, based on the validated questionnaire of Johnson & Johnson,11
In this study, we compared monocular VA in all groups, yet the questionnaires evaluated binocular vision as they were fielded after both eyes had undergone surgery and represent binocular subjective results.
Statistical Analysis
SPSS software (version 21.0; SPSS Inc., Chicago, IL) was used for statistical analysis. Due to the sample size limitations, the nonparametric Mann-Whitney U test was used for the comparison of continuous variables between the study and the control groups. Pearson χ2 or Fisher exact test was used for categorical variables. Patient feedback from the survey was expressed as proportions and assessed as categorical variables. A P -value of <0.05 was considered statistically significant.
Sample Size
Calculations were performed with the G*Power calculator (version 3.1, Dusseldorf, Germany). The calculation of the sample size for the UCDVA is as follows: based on the 2-sided Mann-Whitney test, with 80% power at the 0.05 significance level and a mean difference of 0.1 with a mean SD of 0.1, a total sample size of 28 eyes (14 in each group) is required. The calculation of the sample size for the questionary results is as follows: based on the 2-sided Fisher exact test, with 80% power at the 0.05 significance level and a sample size of n=50 for a case-control ratio of 1:2, similarly to our study, a proportions ratio of 3 could be detected.
Data Availability
The data set used and analyzed during the current study is available from the corresponding author on reasonable request.
RESULTS
Patients
The study included 23 eyes of 23 patients implanted with an EDOF IOL in their second eye and previously implanted with a monofocal IOL targeted for distance in their first eye (group A, MF-EDOF), and 72 eyes of 36 patients that were implanted bilaterally with an EDOF IOL (group B, EDOF-EDOF). All are consecutive cases.
There were no differences in the patients’ characteristics between the groups except for a trend toward higher preoperative astigmatism in group A (Table 1 ).
TABLE 1 -
Baseline Characteristics of Patients
Group A (first eye monofocal, second eye Symfony)
Group B (bilateral Symfony)
P -value
Sex, M (%)
60.9
58.3
0.108
Eye, OD (%)
47.8
50
0.856
Age (y)
Mean±SD, median
64.9±10.9, 65.0
66.4±10.6, 67
0.584
Range [min, max]
25,77
43,85
—
Axial length (mm)
Mean±SD, median
24.4±1.5, 24.0
24.5±1.5, 24.2
0.748
Range [min, max]
22.4, 27.4
21.1, 28.2
—
Anterior chamber depth
Mean±SD, median
3.2±0.3, 3.2
3.4±0.4, 3.3
0.104
Range [min, max]
2.7, 4.0
2.6, 4.3
—
Average keratometry (D)
Mean±SD, median
43.8±1.4, 43.9
43.5±1.6, 43.6
0.221
Range [min, max]
40.9, 46.4
40.8, 47.3
—
Absolute astigmatism (D)
Mean±SD, median
1.5±0.9, 1.3
1.1±0.8, 0.8
0.071
Range min, max
0.4, 3.4
0.0, 5.7
—
HOA/RMS
Mean±SD, median
0.6±0.3, 0.5
0.4±0.2, 0.5
0.665
Range [min, max]
0.3, 1.4
0.2, 1.0
—
IOL power (D)
Mean±SD, median
18.6±4.3, 20
18.8±4.8, 20.5
0.718
Range [min, max]
9.5, 24.5
3.0, 29.0
—
Toric IOL (%)
78.3
44.4
0.0047
Toric IOL power (D)
Mean±SD, median
1.9±1.3, 2.3
2.4±1.2, 2.3
0.475
Range [min, max]
0, 4.5
1.0, 6.0
—
D indicates diopters; HOA, higher-order aberration; IOL, intraocular lens; M, male; max, maximum; min, minimum; mm, millimeter; OD, right eye; RMS, root mean square; y, years.
Visual Outcomes
The mean postoperative refractive spherical equivalent results were similar for the 2 groups achieving slight myopia (Table 2 ).
TABLE 2 -
Postoperative Refraction and Visual Acuity Results (LogMAR)
Group A (first eye monofocal, second eye Symfony)
Group B (bilateral Symfony)
P -value
Postoperative SEQ (D)
Mean±SD, median
−0.2±0.3, −0.1
−0.2±0.2, −0.2
0.594
Range [min, max]
−0.6, 0.5
−0.8, 0.4
—
Postoperative sphere (D)
Mean±SD, median
0.03±0.0, 0.3
0.0±0.2, 0.0
0.979
Range [min, max]
−0.5, 1.25
−0.75, 0.75
—
Postoperative residual astigmatism (D)
Mean±SD, median
−0.4±0.3, −0.5
−0.4±0.4, −0.5
0.894
Range [min, max]
−1.5, 0.0
−1.25, 0.25
—
UCDVA
Mean±SD, median
0.03±0.05, 0.00
0.04±0.16,0.04
0.136
Range [min, max]
0.00, 0.2
−0.7, 0.4
—
UCIVA
Mean±SD, median
0.11±0.1, 0.1
0.09±0.13, 0.1
0.660
Range [min, max]
−0.18, 0.4
−0.2, 0.4
—
UCNVA
Mean±SD, median
0.15±0.14, 0.1
0.23±0.17, 0.18
0.074
Range [min, max]
0.00, 0.48
0.00, 0.7
—
BCDVA
Mean±SD, median
0.01±0.06, 0.00
−0.00±0.18, 0.00
0.573
Range [min, max]
−0.08, 0.20
−0.8, 0.18
—
BCIVA
Mean±SD, median
0.06±0.11, 0.1
0.04±0.11, 0.00
0.317
Range [min, max]
−0.18, 0.2
−0.2, 0.3
—
BCNVA
Mean±SD, median
0.01±0.04, 0.00
0.02±0.05, 0.00
0.880
Range [min, max]
0.00, 0.48
0.00, 0.18
—
D indicates diopter; BCDVA, best-corrected distance visual acuity; BCIVA, best-corrected intermediate visual acuity; BCNVA, best-corrected near visual acuity; LogMAR, logarithm of the minimum angle of resolution; max, maximum; min, minimum; SEQ, spherical equivalent; UCDVA, uncorrected distance visual acuity; UCIVA, uncorrected intermediate visual acuity; UCNVA, uncorrected near visual acuity.
There was no statistically significant difference between the monocular UCDVA in group A (MF-EDOF) (0.03±0.05 LogMAR, Snellen 20/21) compared with the monocular UCDVA in group B (EDOF-EDOF) (0.04±0.16 LogMAR, Snellen 20/22) (P =0.136). The cumulative monocular UCDVA Snellen vision acuity (20/x or better) values for the 2 groups are presented in Figure 1 .
FIGURE 1: Cumulative uncorrected distance visual acuity of groups A and B. Group A: monofocal intraocular lens (IOL) in the first eye and the Symfony IOL in the second eye. Group B: bilateral Symfony IOL. VA indicates visual acuity.
There was no statistically significant difference in the monocular UCIVA between group A (MF-EDOF) (0.11±0.1 LogMAR, Snellen 20/25) compared with the monocular UCIVA group B (EDOF-EDOF) (0.09±0.13 LogMAR, Snellen 20/25) (P =0.660). There was a tendency toward a better monocular UCNVA in group A (0.15±0.14 LogMAR, Snellen 20/28) compared with the monocular UCNVA in group B (0.23±0.17 LogMAR, Snellen 20/33), but the difference was not statistically significant (P =0.074). There was no difference between the groups in the patients’ best-corrected VA for all distances (Table 2 ).
Questionnaires Subjective Outcome
Forty-nine questionnaires were completed by 17/23 (74%) patients in group A (MF-EDOF), and 36/36 (100%) patients in group B (EDOF-EDOF). “Excellent” or “Good” VA perception was reported for distance vision by 15/17 (88.2%) patients and 32/36 (88.9%) patients (P =0.636), for intermediate vision by 11/17 (64.7%) patients and 26/36 (72.2%) patients (P =0.578), and for near vision by 6/17 (35.3%) patients and 11/36 (30.6%) patients (P =0.730), in groups A and B, respectively. Spectacle independence, defined as “Never” or “Rarely” using spectacles, was reported by 16/17 (94.1%) patients and 35/36 (97.2%) patients (P =0.543) for distance vision, 13/17 (76.5%) patients and 32/36 (88.9%) patients (P =0.252) for intermediate vision, and 4/17 (23.6%) patients and 22/36 (61.1%) patients for near vision (P =0.011), in groups A and B, respectively. There were no statistically significant differences in the percentage of patients reported to be spectacle independent for all distances between the groups: 9/17 (52.9%) patients and 28/36 (77.8%) patients in groups A and B, respectively (P =0.066).
Two patients in group A (MF-EDOF) (11.8%) and 5 patients in group B (EDOF-EDOF) (13.9%) reported having haloes and/or glare “Often” or “All the time” (P =1.000). No patients in group A (MF-EDOF) and 2 patients in group B (6.7%) reported that it disturbed their daily life activities (P =0.536). Twelve of 17 (71%) patients in group A (MF-EDOF) and 28/36 (77.8%) patients in group B (EDOF-EDOF) reported that they would choose the same IOL again (P =0.734). The complete self-assessment results are presented in Table 3 .
TABLE 3 -
Postoperative Patient Satisfaction Questionnaire Results
Question
Group A (first eye monofocal, second eye Symfony)
Group B (bilateral Symfony)
P -value
Q1—How would you rate your distance vision?
Very poor (%)
0
0
Poor (%)
0
0
0.636
Fair (%)
11.8
11.1
—
Good (%
35.3
44.4
—
Excellent (%)
52.9
44.4
—
Q2—How would you rate your intermediate vision?
Very poor (%)
0
0
0.578
Poor (%)
5.9
5.6
—
Fair (%)
29.4
22.2
—
Good (%
41.2
36.1
—
Excellent (%)
23.5
36.1
—
Q3—How would you rate your near vision?
Very poor (%)
11.8
25
0.730
Poor (%)
41.2
16.7
Fair (%)
11.8
27.8
—
Good (%
23.5
13.9
—
Excellent (%)
11.8
16.7
—
Q4—How frequently do you use spectacles for distance vision?
All the time (%)
0
2.8
0.543
Often (%)
5.9
0
—
Sometimes (%)
0
0
—
Rarely (%)
23.5
2.8
—
Never (%)
70.6
94.4
—
Q5—How frequently do you use spectacles for intermediate vision?
All the time (%)
0
2.8
0.252
Often (%)
5.9
2.8
—
Sometimes (%)
17.6
5.6
—
Rarely (%)
47.1
5.6
—
Never (%)
29.4
83.3
—
Q6—How frequently do you use spectacles for near vision?
All the time (%)
23.5
25
0.011
Often (%)
35.3
5.6
Sometimes (%)
17.6
8.3
Rarely (%)
11.8
11.1
Never (%)
11.8
50.0
Q7 – How frequently do you use spectacles for any distance?
All the time (%)
11.8
2.8
0.066
Often (%)
11.8
5.6
—
Sometimes (%)
23.5
13.9
—
Rarely (%)
35.3
27.8
—
Never (%)
17.6
50
—
Q8—Do you experience haloes or glare in your vision?
All the time (%)
0
2.8
1.000
Often (%)
11.8
11.1
—
Sometimes (%)
17.6
19.4
—
Rarely (%)
29.4
36.1
—
Never (%)
41.2
30.6
—
Q9—Do the haloes and glare disturb your daily life activities?
All the time (%)
0
0
0.536
Often (%)
0
6.7
—
Sometimes (%)
18.8
3.3
—
Rarely (%)
25
16.7
—
Never (%)
56.6*
73.3†
—
Q10—If you could, would you choose to receive the same IOL again?
No (%)
0
0
0.734
Probably not (%)
5.9
0
—
I do not know (%)
23.5
22.2
—
Probably (%)
17.6
13.88
—
Yes (%)
52.9
63.88
—
* 16/17 patients answered this question.
† 30/36 patients answered this question.
IOL indicates intraocular lens.
DISCUSSION
EDOF IOLs are recommended for bilateral implantation, thus, previous implantation of a monofocal IOL in 1 eye is considered by some surgeons as a contraindication to the implantation of such an IOL in the second eye. Previous studies have demonstrated that fewer photic phenomena are noted in patients implanted with an EDOF IOL bilaterally compared with patients with a multifocal or monofocal IOL bilaterally.11,14–16
The results of this study indicate that patients implanted with a monofocal IOL in the first eye and at least 1 design of an EDOF IOL in the second eye had similar objective and subjective visual outcomes as patients implanted bilaterally with the same EDOF IOL. There was no difference in the spectacle independence for distance and intermediate vision between patients implanted unilaterally or bilaterally with the EDOF IOL. The only exception was that spectacle independence for near vision was reported to be better in the bilateral group, although UCNVA was marginally better in group A. This may represent the advantage of binocularity in group B. Although EDOF lenses enable good vision without glasses for far and intermediate distances, some of the patients also gained functional near vision. Similar findings were also found in other studies.11,17,18
In this study, patients with an EDOF IOL in the second eye had a trend toward higher preoperative astigmatism compared with patients with an EDOF IOL in both eyes, thus, a higher percentage of toric IOL implantation was found in the bilateral group (Table 1 ). The uncorrected VA of patients implanted with the EDOF IOL in only 1 eye were similar to the UCDVA in patients implanted bilaterally with this IOL. No difference was found in the patients’ perception of their VA between the groups for all distances.
Photic phenomena are one of the major concerns when implanting presbyopia correcting IOLs.7 11,19–22 23
Patients’ overall satisfaction was high, which probably reflects the overall high satisfaction from the cataract surgery itself as reported in other studies.12,24
Choi et al25
Several studies have examined the visual outcomes of patients implanted with a multifocal IOL in 1 eye and a monofocal IOL in the other eye. Mayer et al26 27 28 29,30
CONCLUSIONS
In conclusion, the results of this pilot study suggest that patients implanted with a monofocal IOL in previous cataract surgery who are interested in improving their uncorrected visual outcomes can be considered for implantation of at least 1 design of an EDOF IOL in the second eye and may have similar results to those implanted bilaterally with the same EDOF IOL. Further studies are warranted.
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