Cataract surgery with implantation of a monofocal intraocular lens (IOL) in patients with cataract is the most frequently chosen option of surgeons worldwide. It provides excellent distance vision. However, most patients need spectacle correction for near vision postoperatively.
The AMO Array® multifocal IOL has rings of varying optical power with multiple transition zones that allow focus for distance, intermediate, and near vision.1–3 Array IOL implantation is associated with reduced dependence on spectacles for distance and near vision, which increases the patient's satisfaction and quality of life.1–8 Packer and coauthors4 report implantation of the Array IOL as an alternative for presbyopic patients who are motivated to reduce dependence on spectacles. Although many studies show good distance and near visual acuity results,1–7 multifocal IOLs have been associated with an increased incidence of side effects such as halos at night and glare.1,2,4,9
This study evaluated the visual and refractive outcomes and postoperative complications of bilateral Array IOL implantation in patients with and without cataract performed at 1 eye surgery center.
Patients and Methods
A retrospective study was performed to evaluate uncorrected distance acuity, uncorrected near acuity, best spectacle-corrected visual acuity (BSCVA), manifest refraction, and complications 3 months after bilateral implantation of multifocal Array IOLs. Patients were selected to receive the multifocal IOL based on the following criteria: older than 45 years, bilateral cataract or hyperopia of more than +2.0 diopters (D), preoperative keratometric cylinder less than 1.0 D, no preexisting ocular pathology other than cataract, potential postoperative visual acuity of 20/40 or better, and patient motivation after they received an explanation that the surgery could improve distance and near vision and that there was the possibility of postoperative visual aberrations such as halos at night and glare.
Preoperative and postoperative examinations included distance visual acuity (Snellen chart), near vision at 30 cm with and without best distance correction using an illuminated near reading chart (Presby Corp.), slitlamp biomicroscopy, intraocular pressure measurement, manifest refraction, fundoscopy, and corneal topography. The preoperative measurements for IOL power calculation were done by a single technician. The patients had applanation axial length measurement (Nidek Echo Scan US3300). The corneal curvature was estimated using an automated keratometer (Nidek Auto Ref/keratometer ARK-700). The SRK/T formula was used for IOL power calculation; the target was emmetropia or low hyperopia (0 to +0.5 D).
The Array Lens
All patients received an AMO Array SA40N IOL. This zonal-progressive multifocal lens has extruded poly(methyl methacrylate) monofilament haptics. The optic has 5 zones of power with up to +3.5 D of add at the IOL plane for near and distance acuity and to provide intermediate acuity for distances from 50 to 150 cm.
Ninety percent of surgeries were done by 2 surgeons (A.P., J.J.), and the remaining 10% were done by another surgeon (M.D.). All used topical or peribulbar anesthesia. A 3.0 mm, temporal, clear corneal self-sealing incision was made with a diamond knife. The capsulorhexis was created with the goal of overlapping the IOL optic for 360 degrees. A standard divide-and-conquer or phaco-flip technique was used for lens extraction depending on the surgeon's preference and patient's lens density.
Seventy eyes of 35 patients had lens extraction with bilateral implantation of an Array multifocal IOL. Fourteen eyes of 7 patients had hyperopia with presbyopia, and 56 eyes of 28 patients had cataract. The mean age of the patients was 61.54 years ± 11 (SD) (range 46 to 78 years). The mean preoperative sphere in hyperopic eyes was +4.50 ± 2.50 D (range +2.00 to +9.50 D), and the mean cylinder was −0.50 ± 0.48 D (range −0.25 to −1.00 D).
Three months after surgery, the mean sphere was +0.14 ± 0.87 D (range −0.75 to +1.25 D), the mean cylinder was −0.68 ± 0.29 D (range −0.25 to −1.00 D), and the mean spherical equivalent (SE) was −0.24 ± 0.52 D (range −1.25 to + 1.00 D). Figure 1 shows the predictability. Eighty-seven percent of eyes had an SE within ±1.00 D of emmetropia and 56%, within ±0.50 D. Among hyperopic patients, 80% had no change in BSCVA from preoperatively to postoperatively, 20% gained 1 line of BSCVA, and no eye lost lines of BSCVA.
All eyes achieved an uncorrected distance acuity of 20/40 or an uncorrected near acuity of J5 (Figure 2).
One eye had superior decentration of the IOL that was noted under mydriasis 2 weeks after surgery (Figure 3). The uncorrected distance acuity was 20/200, and slitlamp examination showed residual cortex in the inferior capsular bag, which was immediately aspirated in the operating room. One month after the reoperation, the uncorrected distance acuity had improved to 20/40 and the uncorrected near acuity was 20/40 (J5). One patient developed cystoid macular edema that resolved with medical treatment. One patient developed a retinal detachment 4 months after uneventful surgery. This patient required retinal surgery and had a final acuity of counting fingers.
A 3-question survey was administered 3 months postoperatively to assess patient satisfaction. Patients were asked how often they wore glasses. Twenty-two patients (63%) occasionally wore glasses, 11 (31%) never wore glasses, and 2 (6%) always wore glasses.
Patients were asked to rate the effect of glare and halos on general daily activities, reading text on shiny paper, and driving at night. Two patients (6%) reported significant halos and glare around lights at night; however, they reported they were very satisfied with their uncorrected distance and uncorrected near acuities. They were offered pilocarpine 0.5% to reduce halos. Six patients (18%) reported moderate halos that did not disturb daily activities. All patients who reported halos and glare after surgery did not want IOL exchange for a monofocal IOL.
Patients were asked how satisfied they were with the surgery. Twenty-five patients (71%) said they were very satisfied and 9 (26%), satisfied. One patient (3%) was very unsatisfied with her near vision, although it was 20/30 (J4) in both eyes; she said she had not expected to need spectacles for near vision for any activity.
Some studies report that bilateral multifocal IOLs provide distance vision similar to that with monofocal IOLs.1,6–8 Others report better near vision and a greater depth of focus with multifocal IOLs than with monofocal IOLs.1–7 In our study, all eyes achieved an uncorrected distance acuity of 20/40 or better and an uncorrected near acuity of J5 or better. Packer and coauthors4 report that 94.1% of eyes achieved 20/40 and J5 of monocular visual acuity at distance and near, and Javitt and Steinert2 report that 96% of eyes achieved 20/40 or better distance acuity and J3 or better near acuity. These 3 studies show similar results in terms of final uncorrected distance and near acuities 3 months after surgery. Many studies report less frequent use of spectacles for near-vision activities postoperatively in multifocal IOL patients than in monofocal IOL patients.1,6,7 It has also been reported that patients with multifocal IOLs have fewer limitations in their ability to perform social and overall activities without glasses than control patients with monofocal IOLs.1,3
Although multifocal IOLs provide the ability to read comfortably and see at distance without glasses, their implantation is related to a loss of contrast sensitivity, particularly at low-contrast levels,2 and unwanted photic phenomena such as halos and glare.1,2 In our study, 2 patients (6%) reported significant halos and glare around lights at night, and 6 patients (18%) reported moderate halos that did not disturb daily activities. However, none of these patients wanted IOL exchange for a monofocal IOL because they were very satisfied with their distance and near acuities. They were offered pilocarpine 0.5% to reduce halos based on a study that showed most patients report improvement in halos with pupil reduction methods.9 Halos exist on the retinal image because the spread of light is out of focus. Also, theoretical optics suggest that retinal blur circles (ring halos) are influenced by myopic refraction.10,11
One study suggests that individual refractive outcomes influence visual sensations and that simple remediation with overcorrection may mitigate these unwanted visual sensations.9 In our study, the mean SE was −0.24 ± 0.52 D using the SRK/T formula for IOL power calculation. Multifocal IOL implantation is contraindicated in some cases, such as professional drivers who drive at night, because of the increased limitation in night vision.8,9
Multifocal IOL decentration is not well tolerated. One of our patients with significant IOL decentration had an uncorrected distance acuity of 20/200. One month after the IOL was recentered, the uncorrected distance acuity improved to 20/40 and the uncorrected near acuity was J5.
Overall, patients in our study were satisfied with their distance and near vision and with the surgery, although some reported moderate halos and glare postoperatively. The biggest advantage of multifocal IOL implantation is that it can provide good uncorrected distance and near visual acuities, reducing dependence on spectacles. A successful refractive outcome can be obtained with proper patient selection, motivation, and expectations; accurate preoperative biometry and IOL power calculations; and good surgical technique. Enhanced results might be obtained with refinements including immersion or partial coherence interferometry axial length measurements, corneal topography, and a next-generation IOL calculation formula such as the Holladay II.
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10. Lohmann CP, Fitzke FW, O'Brart D, et al. Halos—a problem for all myopes? A comparison between spectacles, contact lenses, and photorefractive keratectomy. Refract Corneal Surg 1993; 9(suppl):S72-S75
11. O'Brart DPS, Lohmann CP, Fitzke FW, et al. Disturbances in night vision after excimer laser photorefractive keratectomy. Eye 1994; 8:46-51