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Clinical evaluation of a five-zone refractive multifocal intraocular lens
Clinical evaluation of a five-zone refractive multifocal intraocular lens Kazuno Negishi, MD, Toshiyuki Nagamoto, MD, Emiko Hara, MD, Daijiro Kurosaka, MD, Hiroko Bissen-Miyajima, MD
ABSTRACT Purpose: To evaluate the clinical performance of a five-zone refractive multifocal intraocular lens (AMO, model MPC-25NB, Array®). Methods: We performed a retrospective clinical trial of 31 cataract patients (mean age 64.3 years). The parameters studied were intraoperative and postoperative complications, distance and near visual acuity, spectacle use, decreased number of corneal endothelial cells, contrast sensitivity, percentage of glare disability, near binocular vision, and depth of focus. Results: Intraoperatively, iris damage occurred in two eyes (4.2%), vitreous loss in one eye (2.1 %), and consecutive rupture of Zinn's zonule and vitreous in one eye (2.1 %). Postoperatively, posterior capsule opacification was observed in two eyes (4.2%), temporary intraocular pressure increase in one eye (2.1 %), and cystoid macular edema in one eye (2.1 %). Uncorrected distance visual acuity of 20/40 or better was achieved by 34 of 37 eyes (91.9%) with less than 1.5 diopters of preoperative keratometric astigmatism; best corrected distance acuity of 20120 or better was achieved by 41 of 45 eyes (91.1 %). Near visual acuity with distance correction of 20/40 or better was achieved by 29 of 43 eyes (67.4%). These data were compared retrospectively with data from control patients who received monofocal lenses, and no significant differences in the decreased number of corneal endothelial cells were found. Mean contrast sensitivities were within normal range for all spatial frequencies. Percentage of glare disability and near binocular vision were within normal limits. Conclusions: Eyes implanted with the five-zone refractive multifocal lens showed better near visual acuity than control eyes and compared favorably in other aspects of visual function, indicating that these lenses are effective and safe. J Cataract Refract Surg 1996; 22: 11 0-115
New diffractive and refractive multifocal intraocular lenses (IOLs) have been developed to overcome the lack of accommodation experienced by patients with monofocal IOLs. When used clinically, some of these IOLs provide
useful distance and near visual acuity; however, decreased contrast sensitivity and glare disability have been reported. 1- 7 In this study, we report the clinical performance ofa five-zone refractive multifocal IOL.
From the Department of Ophthalmology, Keio University School of Medicine, Tokyo, japan.
Subjects and Methods
The authors have no proprietary interest in any product used in this study.
The study group comprised 31 cataract patients (16 men, 15 women) with a mean age of 64.3 years (range 22 to 86 years). Patient selection was based on anticipated benefits and suitability, informed consent, and
Reprint requests to Kdzuno Negishi, MD, Department of Ophthalmology, Keio University School ofMedicine, 35 Shinanomachi, Shinjyukuku, Tokyo 160,japan. 110
J CATARACT REFRACT SURG-VOL 22, JANUARY/FEBRUARY 1996
CLINICAL EVALUATION OF A FIVE-ZONE REFRACTIVE MULTIFOCAL 10L
motivation to function without glasses. Patients were informed that they might require corrective lenses postoperatively. Patients with pathologic ocular changes, potential vision-threatening conditions, or with over 2.5 diopters (D) of preoperative keratometric astigmatism were excluded from the study. After continuous curvilinear capsulorhexis, 48 eyes (43 age-related cataract, 2 traumatic cataract, 2 atopic cataract, and 1 developmental cataract) had phacoemulsification in situ and in-the-bag 10L placement with sodium hyaluronate (Healon®) through a 5.5 mm, selfsealing, corneoscleral frown incision at the 12 o'clock position. In all cases, phacoemulsification was performed using local anesthesia by one surgeon (T.N.). Study patients received information on both the standard monofocal 10L and the multifocal 10L. The Array MPC-25NB lens (Allergan Medical Optics) was implanted in all patients. This multifocal, biconvex, single-piece, poly(methyl methacrylate) 10L has a 6.5 mm optic; five annular refractive zones are incorporated into the 4.7 mm anterior surface diameter, with powers for distance and near focusing in the odd and even zones, respectively. Each zone contains continuous curves of power. Additional power for near focusing is 3.5 D (Figure O. Ofloxacin 0.3% and diclofenac sodium 0.1 % were instilled three times daily for 3 months postoperatively; betamethasone sodium phosphate 0.1 % was instilled five times daily for 1 month postoperatively. Patients were followed over 3 months postoperatively and were evaluated for intraoperative and postoperative complications, distance visual acuity (corrected and uncorrected), near visual acuity (uncorrected, with distance correction, with additional correction) using the Landolt near vision tester, spectacle use, and decreased number of corneal endothelial cells. The number of corneal endothelial cells in study patients was compared with those in 20 patients (20 eyes) (11 men, 9 women) with a mean age of 65.2 years (range 76 to 86 years) in whom monofocal 10Ls had been implanted by the same surgical technique. 8 Patient selection criteria in monofocal cases were equivalent to those in multifocal cases, except monofocal patients did not have motivation to function without glasses. We photographed corneal endothelial cells at 3 months postoperatively using a Konan specular microscope
& ~1;;1 3.5
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Figure 1. (Negishi) Design of the MPC-25NB 10L.
(model CSP 850) and analyzed the data using a Konan cell analyzer (model KC-87A). Contrast sensitivity was measured in all patients using the VCTS 6500 (Vistech) between 1 and 3 months postoperatively. The VCTS 6500, which consists of 45 charts with stripes of different widths and contrasts, is designed to measure contrast sensitivity under normal room luminance at a distance of 10 ft. Percentage of glare disability and near binocular vision were measured in patients who had bilateral 10Ls using the Titmus glare tester and the Titmus stereotest. We also evaluated depth of focus (distance vision with distance correction plus additional power of -6.0 to 4.0 D) at 6 months postoperatively.
Results We implanted a five-zone refractive multifocal 10L in 51 eyes of 31 patients. Three eyes were eliminated
J CATARACT REFRACT SURG-VOL 22, JANUARY/FEBRUARY 1996
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CLINICAL EVALUATION OF A FIVE-ZONE REFRACTIVE MULTI FOCAL IOL
from the study at the patients' request, leaving 48 eyes of 30 patients, which were followed over 3 months. Iris damage occurred in rwo eyes (4.2%), vitreous loss in one eye (2.1%), and consecutive rupture of Zinn's zonule and vitreous loss in one eye (2.1 %). In the latter, who was a 79-year-old patient with age-related cataract, anterior vitrectomy was performed, and the IOL was sutured to the ciliary sulcus. Posterior capsule opacification was observed in rwo eyes (4.2%), intraocular pressure increased temporarily in one eye (2.1 %), and cystoid macular edema (CME) occurred in one eye (2.1 %). The opacification was treated by neodymium: YAG laser; the CME resolved spontaneously. Uncorrected distance and near visual acuity were evaluated in the 37 eyes with less than 1.5 D of preoperative keratometric astigmatism that received an IOL for emmetropia; in other cases the uncorrected visual acuity could be affected by postoperative astigmatism and postoperative refractive error. Corrected distance acuity in three eyes and near acuity in five of 48 eyes were not reported at 3 months for unknown reasons. Uncorrected and corrected distance visual acuities are shown in Table 1. Uncorrected and corrected near visual acuities are shown in Table 2. Twenty of 37 eyes (54.1 %) with less than 1.5 D of preoperative keratometric astigmatism and with an IOL for emmetropia did not require spectacles; 10 eyes (27.0%) required bifocals; and 7 eyes (18.9%) required spectacles for near vision only. The number of corneal endotheli<;ll cells decreased by a mean (±SD) of 11.2 ± 16.5% in eyes with the five-zone refractive multifocal IOL (n = 34) and 7.4 ± 4.9% in eyes with a monofocal IOL (n = 20). There was no significant difference between the two types ofIOLs (P = 2.009, t-test).
Table 1. Uncorrected and corrected distance visual acuity. Uncorrected (n 37)*
Corrected (n = 45)
=
Visual Acuity ;::20/20 20/25 to 20/40 20/50 to 20/200
Number Number of of Eyes Percentage Eyes Percentage 13 21 3
35 .1 56.8 8.1
* Preoperative keratometric cylinder
112
41 3
< 1.5 diopters
91.1 6.7 2.2
Contrast sensitivity measurements in the 48 eyes that received the five-zone refractive multifocal IOL are shown in Figure 2. Postoperative mean contrast sensitivity measurements are shown in Figure 3. These were within normal range for all spatial frequencies. Glare disability results in the 48 eyes are shown in Table 3. Mean glare disability was 6.3 ± 2.3%, which was within normal limits. All 17 patients who had stereoscopic vision testing using the Titmus stereo test were able to perceive the "fly" (3000 seconds of arc). Sixteen (94%) showed stereoacuity equal to or better than circle number 8 (50 seconds of arc) on the test. Depth of focus measurements 6 months postoperatively are shown in Figure 4. Distance visual acuity reached useful levels (20/50 or better) even with additional power ranging from -4.0 to -0.5 D (near to intermediate focus).
Discussion Four intraoperative complications were observed in three patients, while postoperative complications were found in four eyes of four patients. None altered the visual outcome, indicating that the five-zone refractive multifocal IOL is safe for implantation. No significant difference in the decreased number of corneal endothelial cells was observed berween the patients who received multifocal and monofocal IOLs. Corneal endothelial cell loss occurred as a result of surgery, not as a result of the IOL, indicating that the fivezone refractive multifocal IOL is safe for implantation. Uncorrected distance acuity of 20/40 or better was achieved by 34 of37 eyes (91.9%) with less than 1.5 D of preoperative keratometric astigmatism and with an IOL for emmetropia. Gimbel and coauthors 1 reported uncorrected distance acuity of 20/40 or better in 98 of 13 1 eyes (74.8%) with diffractive multifocal IOLs and in 115 of 147 control eyes with monofocal IOLs (78 .2%). In our study, corrected distance acuity measurements were 20/20 or better in 41 eyes (91.1 %). These results were better than those measured in patients who received diffractive multifocal IOLs and were comparable to measurements achieved in controls with monofocal IOLs. 1 Gimbel and coauthors 1 reported a corrected distance acuity of 20/25 or better in 132 eyes (78.9%)
) CATARACT REFRACT SURG- VO L 22. )ANUARY/FEBRUARY 1996
CLINICAL EVALUATION OF A FIVE-ZONE REFRACTIVE MULTIFOCAL IOL
Table 2.
Uncorrected and corrected near visual acuity. With Distance Correction (n = 43)
Uncorrected (n = 37)*
Visual Acuity 2:20/30 20/31 to 20/40 20/50 to 20/200
Number of Eyes
13 10 14
* Preoperative keratometric cylinder
Percentage
Number of Eyes
Percentage
35.1 27.0 37.8
13 16 14
30.2 37.2 32.6
4.4 2.2
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18
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Figure 2. (Negishi) Postoperative contrast sensitivity. The shl:jded region shows the normal range of contrast sensitivity.
Figure 3. (Negishi) Mean postoperative contrast sensitivities. The shaded region shows the normal range of contrast sensitivity.
that received the diffractive multifocal IOL. Steinert et a1. 6 reported a corrected distance acuity of20125 or better in 28 of32 eyes (88.0%) with the five-zone refractive multifocal IOL. While differences in surgical technique, heterogeneity of population sampled, and sample size may exist, evidence indicates that distance acuity in eyes with the five-zone refractive multifocal IOL is comparable to that in eyes with monofocal and diffractive multifocallOLs. Uncorrected near visual acuity of 20/40 or better was achieved in 23 eyes (62.2%); .however, acuity of 20/30 or better was achieved in only 13 eyes (35.1 %). These results are attributed to the emphasis of the fivezone refractive multifocallens on distance visual acuity.
Gimbel and coauthors 1 reported that near visual acuity measutements with the diffractive multifocal IOL were between]l and]3 in 71 eyes (54%), while Steinert et a1. 6 reported that mean uncorrected near acuity with the Table 3.
Percentage of glare disability.
Percentage Glare Disability
5.0 7.5 10.0 12.5 15.0
J CATARACT REFRACT SURG---VOL 22, JANUARY/FEBRUARY 1996
Number of Eyes
29 14
2 2
Percentage
60.4 29.1 4.2 4.2 2.1
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CLINICAL EVALUATION OF A FIVE-ZONE REFRACTIVE MULTIFOCAL IOL
1.0 l--------+---P>:r--------t visual acuity
0.4
O. 1 L~--_ _~-_-l---_ _ _----! o 4 -4 -2 2 Additional power
Figure 4. (Negishi) Depth of focus 6 months postoperatively (n = 20). Graph of distance visual acuity with additional power.
five-zone refractive multifocal 10L was J3, significantly better than with monofocal 10Ls. The additional power required for the best near vision was significantly lower than that required with monofocal IOLs. 6 Our results indicated that 20 eyes (54.1 %) did not require spectacles for near or distance vision. This agrees with the finding of Steinert et al., 6 who reported that 16 eyes (52%) with the five-zone refractive multifocal 10L did not need spectacles. Because spectacle use may be affected by the postoperative spherical power or the status of the fellow eye, this parameter cannot be compared with other study results. However, patients with the five-zone refractive multifocal 10L require spectacles more frequently than patients with diffractive multifocal 10Ls. Even so, the useful near visual acuity reached 20/40 or better in 23 eyes (62.2%). These results were attributed to the 10L design, which emphasizes distance VISIon. Gimbel and coauthors 1 reported that 63% of patients with diffractive multifocal 10Ls did not need spectacles and that of those who received bilateral diffractive multifocal 10Ls, 14% needed bifocals; 72% of patients with bilateral monofocal 10Ls needed bifocals, and only 4% did not need spectacles. Percival2 reported that 69% of patients with diffractive multifocal 10Ls did not need spectacles for daily use. Our results indicate that the five-zone refractive multifocal 10L may be more useful than monofocal or diffractive multifocal 10Ls because they can provide a level of distance vision comparable to that in patients with monofocallenses and are useful for near vision. 114
Mean postoperative contrast sensitivities were within normal range for all spatial frequencies, suggesting that the five-zone refractive multifocal 10L may be useful when lower contrast vision is needed and that its design, incorporating continuous curves of power into the 10L surface, is responsible for preventing light from scattering or diffracting. In the diffractive multifocal 10L, 82% of light is focused for distance or near image and 18% is scattered. However, decreased contrast sensitivity was reported in patients with the five-zone refractive multifocal 101. This contradiction might be attributed to the difference in methods of measurement; however, more studies should be performed to evaluate this parameter. Previous studies have reported on contrast sensitiv.Ity or contrast Vlsua . I acUIty. . 1-79 d coau" 10 G'1m b e ian l thors reported that contrast sensitivity decreased markedly in the low-contrast range in 131 eyes with diffractive multifocal 10Ls. Olsen and Corydon 5 reported that the contrast visual acuity (Regan score) in patients with diffractive multifocal 10Ls was significantly lower in the medium-contrast range than the contrast acuity in patients with monofocal 10Ls. On the other hand, Steinert et al. 6 reported that the Regan score in patients with the five-zone refractive multifocal 10L in one eye decreased by a half line at high-contrast levels of 96%, 50%, and 25%, compared with patients using monofocal 10Ls. This difference was not statistically significant; however, at the 11 % contrast level, there was a significant decrease of approximately 2.4 lines between the two groups, although no complaints could be attributed to decreased contrast sensitivity in a questionnaire designed to evaluate patient satisfaction. In the present study, a postoperative percentage of glare disability of 7.5% or less was observed in almost 90% of patients; the mean percentage glare disability of 6.3% was within normal limits. These results can be attributed to the design of the five-zone refractive multifocal 10L, which prevents light diffraction or scattering. Gimbel and coauthors 1 reported that questionnaire responses from patients with diffractive multifocal lenses showed a significantly higher proportion of visual problems (halos or glare) than from patients with monofocal 10Ls. Percival 2 reported that 40 patients (73%) with diffractive multifocallenses were satisfied with the
J CATARACT REFRACT SURG-VOL 22, JANUARY/FEBRUARY 1996
CLINICAL EVALUATION OF A FIVE-ZONE REFRACTIVE MULTIFOCAL IOL
surgical results, that 48 patients (87%) with monofocal IOLs were satisfied with their visual function, and that there were no significant differences between the two groups. Steinert et al. 6 found no significant difference between similar groups when grading visual acuity under different environmental conditions, including glare and night vision. We measured only stereovision with near correction. The results were comparable to those with monofocal IOLs,lJ although we have not evaluated binocular vision without correction or with distance correction. Binocular vision should be measured under such conditions. Olsen and Corydon 5 reported that two peaks occur around 0 D and 3.0 D in the defocus curve of the diffractive multifocal IOL, and the former was significantly lower than that occurring with the monofocal IOL. We found that while the defocus curve had two peaks, the patients' distance visual acuity appeared superior to the near visual acuity. The distance acuity of patients with the five-zone refractive multifocal IOL could be considered comparable to that of patients with monofocal IOLs. As shown in the defocus curve, near visual acuity reached useful levels, and the intermediate vision was preserved. This can be attributed to the IOL design; that is, the amount of light entering through the zone for distance focusing is higher than in the diffractive multifocal IOL and there is a continuous curve of the power between the zones for distance and near focusing.
Conclusion Although this was a small-sample retrospective study with short-term follow-up, our results suggest that the five-zone refractive multifocal IOL may provide good distance vision comparable to that with monofocal IOLs without decreased contrast sensitivity and useful near vision that does not require spectacles. This IOL
can be used with more patients than the diffractive multifocal IOL; however, because the mean uncorrected near visual acuity was lower than that achieved with the diffractive multifocal IOL, the five-zone refractive multifocal IOL requires further refinements and longer follow-up.
References 1. Gimbel HV, Sanders DR, Raanan MG. Visual and refractive results of multifocal intraocular lenses. Ophthalmology 1991; 98:881-888 2. Percival SPB. Perspective study of the new diffractive bifocal intraocular lens. Eye 1989; 3:571-575 3. Atebara NH, Miller D. An optical model to describe image contrast with bifocal intraocular lenses. Am J Ophthalmol 1990; 110: 172-177 4. Holladay JT, van Dijk H, Lang A, et al. Optical performance of multifocal intraocular lenses. J Cataract Refract Surg 1990; 16:413-422 5. Olsen T, Corydon L. Contrast sensitivity as a function of focus in patients with the diffractive multifocal intraocular lens. J Cataract Refract Surg 1990; 16:703-706 6. Steinert RF, Post CT Jr, Brint SF, et al. A prospective, randomized, double-masked comparison of a zonalprogressive multifocal intraocular lens and a monofocal intraocular lens. Ophthalmology 1992; 99:853-860 7. Betto K, Majima Y, Kurobe N. Contrast sensitivity in diffractive multifocal implantations. IOL Qpn) 1992; 6:173-177 8. Muto K, Tsunoda K, Kurosaka D, Nagamoto T. Complications and postoperative inflammation in no-stitch cataract surgery. Eye Qpn) 1992; 10:823- 827 9. Miyajima H, Katsumi 0, Ogawa T, Wang GJ. Contrast visual acuities in cataract patients. II. After IOL implantation. Acta OphthalmoI1992; 70:427-433 10. Lehmann RP. Paired comparison of contrast sensitivity in diffractive multifocal IOLs and conventional monofocal IOLs. Aust NZ J Ophthalmol1990; 18:325-328 11. Katsumi 0, Miyajima H, Ogawa T, Hirose T. Aniseikonia and stereoacuity in pseudophakic patients; unilateral and bilateral cases. Ophthalmology 1992; 99:1270-1277
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ABSTRACT Purpose: To evaluate the clinical performance of a five-zone refractive multifocal intraocular lens (AMO, model MPC-25NB, Array®). Methods: We performed a retrospective clinical trial of 31 cataract patients (mean age 64.3 years). The parameters studied were intraoperative and postoperative complications, distance and near visual acuity, spectacle use, decreased number of corneal endothelial cells, contrast sensitivity, percentage of glare disability, near binocular vision, and depth of focus. Results: Intraoperatively, iris damage occurred in two eyes (4.2%), vitreous loss in one eye (2.1 %), and consecutive rupture of Zinn's zonule and vitreous in one eye (2.1 %). Postoperatively, posterior capsule opacification was observed in two eyes (4.2%), temporary intraocular pressure increase in one eye (2.1 %), and cystoid macular edema in one eye (2.1 %). Uncorrected distance visual acuity of 20/40 or better was achieved by 34 of 37 eyes (91.9%) with less than 1.5 diopters of preoperative keratometric astigmatism; best corrected distance acuity of 20120 or better was achieved by 41 of 45 eyes (91.1 %). Near visual acuity with distance correction of 20/40 or better was achieved by 29 of 43 eyes (67.4%). These data were compared retrospectively with data from control patients who received monofocal lenses, and no significant differences in the decreased number of corneal endothelial cells were found. Mean contrast sensitivities were within normal range for all spatial frequencies. Percentage of glare disability and near binocular vision were within normal limits. Conclusions: Eyes implanted with the five-zone refractive multifocal lens showed better near visual acuity than control eyes and compared favorably in other aspects of visual function, indicating that these lenses are effective and safe. J Cataract Refract Surg 1996; 22: 11 0-115
New diffractive and refractive multifocal intraocular lenses (IOLs) have been developed to overcome the lack of accommodation experienced by patients with monofocal IOLs. When used clinically, some of these IOLs provide
useful distance and near visual acuity; however, decreased contrast sensitivity and glare disability have been reported. 1- 7 In this study, we report the clinical performance ofa five-zone refractive multifocal IOL.
From the Department of Ophthalmology, Keio University School of Medicine, Tokyo, japan.
Subjects and Methods
The authors have no proprietary interest in any product used in this study.
The study group comprised 31 cataract patients (16 men, 15 women) with a mean age of 64.3 years (range 22 to 86 years). Patient selection was based on anticipated benefits and suitability, informed consent, and
Reprint requests to Kdzuno Negishi, MD, Department of Ophthalmology, Keio University School ofMedicine, 35 Shinanomachi, Shinjyukuku, Tokyo 160,japan. 110
J CATARACT REFRACT SURG-VOL 22, JANUARY/FEBRUARY 1996
CLINICAL EVALUATION OF A FIVE-ZONE REFRACTIVE MULTIFOCAL 10L
motivation to function without glasses. Patients were informed that they might require corrective lenses postoperatively. Patients with pathologic ocular changes, potential vision-threatening conditions, or with over 2.5 diopters (D) of preoperative keratometric astigmatism were excluded from the study. After continuous curvilinear capsulorhexis, 48 eyes (43 age-related cataract, 2 traumatic cataract, 2 atopic cataract, and 1 developmental cataract) had phacoemulsification in situ and in-the-bag 10L placement with sodium hyaluronate (Healon®) through a 5.5 mm, selfsealing, corneoscleral frown incision at the 12 o'clock position. In all cases, phacoemulsification was performed using local anesthesia by one surgeon (T.N.). Study patients received information on both the standard monofocal 10L and the multifocal 10L. The Array MPC-25NB lens (Allergan Medical Optics) was implanted in all patients. This multifocal, biconvex, single-piece, poly(methyl methacrylate) 10L has a 6.5 mm optic; five annular refractive zones are incorporated into the 4.7 mm anterior surface diameter, with powers for distance and near focusing in the odd and even zones, respectively. Each zone contains continuous curves of power. Additional power for near focusing is 3.5 D (Figure O. Ofloxacin 0.3% and diclofenac sodium 0.1 % were instilled three times daily for 3 months postoperatively; betamethasone sodium phosphate 0.1 % was instilled five times daily for 1 month postoperatively. Patients were followed over 3 months postoperatively and were evaluated for intraoperative and postoperative complications, distance visual acuity (corrected and uncorrected), near visual acuity (uncorrected, with distance correction, with additional correction) using the Landolt near vision tester, spectacle use, and decreased number of corneal endothelial cells. The number of corneal endothelial cells in study patients was compared with those in 20 patients (20 eyes) (11 men, 9 women) with a mean age of 65.2 years (range 76 to 86 years) in whom monofocal 10Ls had been implanted by the same surgical technique. 8 Patient selection criteria in monofocal cases were equivalent to those in multifocal cases, except monofocal patients did not have motivation to function without glasses. We photographed corneal endothelial cells at 3 months postoperatively using a Konan specular microscope
& ~1;;1 3.5
L-..,.....!-n--+>ofD-..J,;,.o~::",...-.--=::::..;.~J-o_wn~.--._ ,
DC>/':.....' I I I
, I
"I
I
I
"
,-I
,I'!
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I
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1
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Zone 1 Zone 2 Zone 3 Zone 4 Zone 5
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I
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,I
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Figure 1. (Negishi) Design of the MPC-25NB 10L.
(model CSP 850) and analyzed the data using a Konan cell analyzer (model KC-87A). Contrast sensitivity was measured in all patients using the VCTS 6500 (Vistech) between 1 and 3 months postoperatively. The VCTS 6500, which consists of 45 charts with stripes of different widths and contrasts, is designed to measure contrast sensitivity under normal room luminance at a distance of 10 ft. Percentage of glare disability and near binocular vision were measured in patients who had bilateral 10Ls using the Titmus glare tester and the Titmus stereotest. We also evaluated depth of focus (distance vision with distance correction plus additional power of -6.0 to 4.0 D) at 6 months postoperatively.
Results We implanted a five-zone refractive multifocal 10L in 51 eyes of 31 patients. Three eyes were eliminated
J CATARACT REFRACT SURG-VOL 22, JANUARY/FEBRUARY 1996
111
CLINICAL EVALUATION OF A FIVE-ZONE REFRACTIVE MULTI FOCAL IOL
from the study at the patients' request, leaving 48 eyes of 30 patients, which were followed over 3 months. Iris damage occurred in rwo eyes (4.2%), vitreous loss in one eye (2.1%), and consecutive rupture of Zinn's zonule and vitreous loss in one eye (2.1 %). In the latter, who was a 79-year-old patient with age-related cataract, anterior vitrectomy was performed, and the IOL was sutured to the ciliary sulcus. Posterior capsule opacification was observed in rwo eyes (4.2%), intraocular pressure increased temporarily in one eye (2.1 %), and cystoid macular edema (CME) occurred in one eye (2.1 %). The opacification was treated by neodymium: YAG laser; the CME resolved spontaneously. Uncorrected distance and near visual acuity were evaluated in the 37 eyes with less than 1.5 D of preoperative keratometric astigmatism that received an IOL for emmetropia; in other cases the uncorrected visual acuity could be affected by postoperative astigmatism and postoperative refractive error. Corrected distance acuity in three eyes and near acuity in five of 48 eyes were not reported at 3 months for unknown reasons. Uncorrected and corrected distance visual acuities are shown in Table 1. Uncorrected and corrected near visual acuities are shown in Table 2. Twenty of 37 eyes (54.1 %) with less than 1.5 D of preoperative keratometric astigmatism and with an IOL for emmetropia did not require spectacles; 10 eyes (27.0%) required bifocals; and 7 eyes (18.9%) required spectacles for near vision only. The number of corneal endotheli<;ll cells decreased by a mean (±SD) of 11.2 ± 16.5% in eyes with the five-zone refractive multifocal IOL (n = 34) and 7.4 ± 4.9% in eyes with a monofocal IOL (n = 20). There was no significant difference between the two types ofIOLs (P = 2.009, t-test).
Table 1. Uncorrected and corrected distance visual acuity. Uncorrected (n 37)*
Corrected (n = 45)
=
Visual Acuity ;::20/20 20/25 to 20/40 20/50 to 20/200
Number Number of of Eyes Percentage Eyes Percentage 13 21 3
35 .1 56.8 8.1
* Preoperative keratometric cylinder
112
41 3
< 1.5 diopters
91.1 6.7 2.2
Contrast sensitivity measurements in the 48 eyes that received the five-zone refractive multifocal IOL are shown in Figure 2. Postoperative mean contrast sensitivity measurements are shown in Figure 3. These were within normal range for all spatial frequencies. Glare disability results in the 48 eyes are shown in Table 3. Mean glare disability was 6.3 ± 2.3%, which was within normal limits. All 17 patients who had stereoscopic vision testing using the Titmus stereo test were able to perceive the "fly" (3000 seconds of arc). Sixteen (94%) showed stereoacuity equal to or better than circle number 8 (50 seconds of arc) on the test. Depth of focus measurements 6 months postoperatively are shown in Figure 4. Distance visual acuity reached useful levels (20/50 or better) even with additional power ranging from -4.0 to -0.5 D (near to intermediate focus).
Discussion Four intraoperative complications were observed in three patients, while postoperative complications were found in four eyes of four patients. None altered the visual outcome, indicating that the five-zone refractive multifocal IOL is safe for implantation. No significant difference in the decreased number of corneal endothelial cells was observed berween the patients who received multifocal and monofocal IOLs. Corneal endothelial cell loss occurred as a result of surgery, not as a result of the IOL, indicating that the fivezone refractive multifocal IOL is safe for implantation. Uncorrected distance acuity of 20/40 or better was achieved by 34 of37 eyes (91.9%) with less than 1.5 D of preoperative keratometric astigmatism and with an IOL for emmetropia. Gimbel and coauthors 1 reported uncorrected distance acuity of 20/40 or better in 98 of 13 1 eyes (74.8%) with diffractive multifocal IOLs and in 115 of 147 control eyes with monofocal IOLs (78 .2%). In our study, corrected distance acuity measurements were 20/20 or better in 41 eyes (91.1 %). These results were better than those measured in patients who received diffractive multifocal IOLs and were comparable to measurements achieved in controls with monofocal IOLs. 1 Gimbel and coauthors 1 reported a corrected distance acuity of 20/25 or better in 132 eyes (78.9%)
) CATARACT REFRACT SURG- VO L 22. )ANUARY/FEBRUARY 1996
CLINICAL EVALUATION OF A FIVE-ZONE REFRACTIVE MULTIFOCAL IOL
Table 2.
Uncorrected and corrected near visual acuity. With Distance Correction (n = 43)
Uncorrected (n = 37)*
Visual Acuity 2:20/30 20/31 to 20/40 20/50 to 20/200
Number of Eyes
13 10 14
* Preoperative keratometric cylinder
Percentage
Number of Eyes
Percentage
35.1 27.0 37.8
13 16 14
30.2 37.2 32.6
4.4 2.2
.003
® ®
.01
.~
20/15
.';:: 1Z!
0 100 .,...,
.01
.~
20/15
.';:: 1Z!
rro
30
20/20
~
L
I=:
()
93.4
300
.003
0 100 .,...,
0
42
(n==48)
®
&J
Percentage
< 1.5 D
300
1Z!
Number of Eyes
2
(n==48)
...... 1Z! ro ......
Best Corrected (n = 45)
10
®
20/25
I 20/30
® 20/100§
3
CD .3
CD
®
®
©
3 6 12 spatial frequency (cycle per degree)
1.5
I=:
Q) 1Z!
...... 1Z! ro
@
.b I=:
0
()
r"L
30 20/70
@ @
10
r
20/20
®
® ®
20/25
I
20/30
20/100§
CD
3
CD
20/50
©
®
®
@
3 6 12 spatial frequency (cycle per degree)
18
1.5
.3
®
18
Figure 2. (Negishi) Postoperative contrast sensitivity. The shl:jded region shows the normal range of contrast sensitivity.
Figure 3. (Negishi) Mean postoperative contrast sensitivities. The shaded region shows the normal range of contrast sensitivity.
that received the diffractive multifocal IOL. Steinert et a1. 6 reported a corrected distance acuity of20125 or better in 28 of32 eyes (88.0%) with the five-zone refractive multifocal IOL. While differences in surgical technique, heterogeneity of population sampled, and sample size may exist, evidence indicates that distance acuity in eyes with the five-zone refractive multifocal IOL is comparable to that in eyes with monofocal and diffractive multifocallOLs. Uncorrected near visual acuity of 20/40 or better was achieved in 23 eyes (62.2%); .however, acuity of 20/30 or better was achieved in only 13 eyes (35.1 %). These results are attributed to the emphasis of the fivezone refractive multifocallens on distance visual acuity.
Gimbel and coauthors 1 reported that near visual acuity measutements with the diffractive multifocal IOL were between]l and]3 in 71 eyes (54%), while Steinert et a1. 6 reported that mean uncorrected near acuity with the Table 3.
Percentage of glare disability.
Percentage Glare Disability
5.0 7.5 10.0 12.5 15.0
J CATARACT REFRACT SURG---VOL 22, JANUARY/FEBRUARY 1996
Number of Eyes
29 14
2 2
Percentage
60.4 29.1 4.2 4.2 2.1
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CLINICAL EVALUATION OF A FIVE-ZONE REFRACTIVE MULTIFOCAL IOL
1.0 l--------+---P>:r--------t visual acuity
0.4
O. 1 L~--_ _~-_-l---_ _ _----! o 4 -4 -2 2 Additional power
Figure 4. (Negishi) Depth of focus 6 months postoperatively (n = 20). Graph of distance visual acuity with additional power.
five-zone refractive multifocal 10L was J3, significantly better than with monofocal 10Ls. The additional power required for the best near vision was significantly lower than that required with monofocal IOLs. 6 Our results indicated that 20 eyes (54.1 %) did not require spectacles for near or distance vision. This agrees with the finding of Steinert et al., 6 who reported that 16 eyes (52%) with the five-zone refractive multifocal 10L did not need spectacles. Because spectacle use may be affected by the postoperative spherical power or the status of the fellow eye, this parameter cannot be compared with other study results. However, patients with the five-zone refractive multifocal 10L require spectacles more frequently than patients with diffractive multifocal 10Ls. Even so, the useful near visual acuity reached 20/40 or better in 23 eyes (62.2%). These results were attributed to the 10L design, which emphasizes distance VISIon. Gimbel and coauthors 1 reported that 63% of patients with diffractive multifocal 10Ls did not need spectacles and that of those who received bilateral diffractive multifocal 10Ls, 14% needed bifocals; 72% of patients with bilateral monofocal 10Ls needed bifocals, and only 4% did not need spectacles. Percival2 reported that 69% of patients with diffractive multifocal 10Ls did not need spectacles for daily use. Our results indicate that the five-zone refractive multifocal 10L may be more useful than monofocal or diffractive multifocal 10Ls because they can provide a level of distance vision comparable to that in patients with monofocallenses and are useful for near vision. 114
Mean postoperative contrast sensitivities were within normal range for all spatial frequencies, suggesting that the five-zone refractive multifocal 10L may be useful when lower contrast vision is needed and that its design, incorporating continuous curves of power into the 10L surface, is responsible for preventing light from scattering or diffracting. In the diffractive multifocal 10L, 82% of light is focused for distance or near image and 18% is scattered. However, decreased contrast sensitivity was reported in patients with the five-zone refractive multifocal 101. This contradiction might be attributed to the difference in methods of measurement; however, more studies should be performed to evaluate this parameter. Previous studies have reported on contrast sensitiv.Ity or contrast Vlsua . I acUIty. . 1-79 d coau" 10 G'1m b e ian l thors reported that contrast sensitivity decreased markedly in the low-contrast range in 131 eyes with diffractive multifocal 10Ls. Olsen and Corydon 5 reported that the contrast visual acuity (Regan score) in patients with diffractive multifocal 10Ls was significantly lower in the medium-contrast range than the contrast acuity in patients with monofocal 10Ls. On the other hand, Steinert et al. 6 reported that the Regan score in patients with the five-zone refractive multifocal 10L in one eye decreased by a half line at high-contrast levels of 96%, 50%, and 25%, compared with patients using monofocal 10Ls. This difference was not statistically significant; however, at the 11 % contrast level, there was a significant decrease of approximately 2.4 lines between the two groups, although no complaints could be attributed to decreased contrast sensitivity in a questionnaire designed to evaluate patient satisfaction. In the present study, a postoperative percentage of glare disability of 7.5% or less was observed in almost 90% of patients; the mean percentage glare disability of 6.3% was within normal limits. These results can be attributed to the design of the five-zone refractive multifocal 10L, which prevents light diffraction or scattering. Gimbel and coauthors 1 reported that questionnaire responses from patients with diffractive multifocal lenses showed a significantly higher proportion of visual problems (halos or glare) than from patients with monofocal 10Ls. Percival 2 reported that 40 patients (73%) with diffractive multifocallenses were satisfied with the
J CATARACT REFRACT SURG-VOL 22, JANUARY/FEBRUARY 1996
CLINICAL EVALUATION OF A FIVE-ZONE REFRACTIVE MULTIFOCAL IOL
surgical results, that 48 patients (87%) with monofocal IOLs were satisfied with their visual function, and that there were no significant differences between the two groups. Steinert et al. 6 found no significant difference between similar groups when grading visual acuity under different environmental conditions, including glare and night vision. We measured only stereovision with near correction. The results were comparable to those with monofocal IOLs,lJ although we have not evaluated binocular vision without correction or with distance correction. Binocular vision should be measured under such conditions. Olsen and Corydon 5 reported that two peaks occur around 0 D and 3.0 D in the defocus curve of the diffractive multifocal IOL, and the former was significantly lower than that occurring with the monofocal IOL. We found that while the defocus curve had two peaks, the patients' distance visual acuity appeared superior to the near visual acuity. The distance acuity of patients with the five-zone refractive multifocal IOL could be considered comparable to that of patients with monofocal IOLs. As shown in the defocus curve, near visual acuity reached useful levels, and the intermediate vision was preserved. This can be attributed to the IOL design; that is, the amount of light entering through the zone for distance focusing is higher than in the diffractive multifocal IOL and there is a continuous curve of the power between the zones for distance and near focusing.
Conclusion Although this was a small-sample retrospective study with short-term follow-up, our results suggest that the five-zone refractive multifocal IOL may provide good distance vision comparable to that with monofocal IOLs without decreased contrast sensitivity and useful near vision that does not require spectacles. This IOL
can be used with more patients than the diffractive multifocal IOL; however, because the mean uncorrected near visual acuity was lower than that achieved with the diffractive multifocal IOL, the five-zone refractive multifocal IOL requires further refinements and longer follow-up.
References 1. Gimbel HV, Sanders DR, Raanan MG. Visual and refractive results of multifocal intraocular lenses. Ophthalmology 1991; 98:881-888 2. Percival SPB. Perspective study of the new diffractive bifocal intraocular lens. Eye 1989; 3:571-575 3. Atebara NH, Miller D. An optical model to describe image contrast with bifocal intraocular lenses. Am J Ophthalmol 1990; 110: 172-177 4. Holladay JT, van Dijk H, Lang A, et al. Optical performance of multifocal intraocular lenses. J Cataract Refract Surg 1990; 16:413-422 5. Olsen T, Corydon L. Contrast sensitivity as a function of focus in patients with the diffractive multifocal intraocular lens. J Cataract Refract Surg 1990; 16:703-706 6. Steinert RF, Post CT Jr, Brint SF, et al. A prospective, randomized, double-masked comparison of a zonalprogressive multifocal intraocular lens and a monofocal intraocular lens. Ophthalmology 1992; 99:853-860 7. Betto K, Majima Y, Kurobe N. Contrast sensitivity in diffractive multifocal implantations. IOL Qpn) 1992; 6:173-177 8. Muto K, Tsunoda K, Kurosaka D, Nagamoto T. Complications and postoperative inflammation in no-stitch cataract surgery. Eye Qpn) 1992; 10:823- 827 9. Miyajima H, Katsumi 0, Ogawa T, Wang GJ. Contrast visual acuities in cataract patients. II. After IOL implantation. Acta OphthalmoI1992; 70:427-433 10. Lehmann RP. Paired comparison of contrast sensitivity in diffractive multifocal IOLs and conventional monofocal IOLs. Aust NZ J Ophthalmol1990; 18:325-328 11. Katsumi 0, Miyajima H, Ogawa T, Hirose T. Aniseikonia and stereoacuity in pseudophakic patients; unilateral and bilateral cases. Ophthalmology 1992; 99:1270-1277
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