From the Department of Ophthalmology, Hong Kong Sanatorium and Hospital, Hong Kong.
Dr Chang is a consultant for and receives travel expenses from Abbott Medical Optics. The remaining authors have no financial interest in the materials presented herein.
Study concept and design (J.S.M.C., J.C.M.N., S.Y.F.L.); data collection (J.C.M.N., S.Y.F.L.); analysis and interpretation (J.S.M.C., J.C.M.N., S.Y.F.L.); drafting of the manuscript (J.S.M.C., J.C.M.N., S.Y.F.L.); critical revision of the manuscript (J.S.M.C., S.Y.F.L.); statistical expertise (S.Y.F.L.); administrative, technical, or material support (S.Y.F.L.); supervision (S.Y.F.L.)
Correspondence: Silvania Y.F. Lau, MPhil, 8/F, Li Shu Pui Block, Phase II, 2 Village Rd, Happy Valley, Hong Kong. Tel: 852 28358885; Fax: 852 28358887; E-mail: email@example.com
A recent study of bilateral refractive lens exchange (RLE) for presbyopic correction in emmetropes found that a pupil-dependent diffractive multifocal intraocular lens (IOL) was safe and effective and high patient satisfaction was reported.1 However, offering RLE with a monofocal IOL, multifocal IOL, or even bilateral multifocal IOL to emmetropic patients is a contentious clinical decision, especially when postoperative halo and glare are concerns. In this retrospective study, we evaluated the safety and efficacy of RLE with a pupil-independent diffractive multifocal IOL. We also compared the severity of symptoms and patient satisfaction with visual performance between patients with and without habitual spectacle use (defined as requiring spectacles for most daily activities), as well as patients who had unilateral versus bilateral RLE. We attempted to identify the most suitable group of patients for RLE according to these patients’ characteristics.
Patients and Methods
This retrospective study evaluated patients who underwent RLE with a Tecnis acrylic multifocal IOL (ZMA00; Abbott Laboratories, Abbott Park, Illinois) in one eye or both eyes between May 2008 and January 2011. The study was approved by the hospital ethics committee. Patients with presbyopia ⩾1.50 diopters (D) with preoperative uncorrected distance visual acuity (UDVA) or corrected distance visual acuity (CDVA) of 20/20 or better were enrolled.
All patients underwent phacoemulsification lens extraction with a 2.7-mm clear corneal incision, and all surgeries were performed by a single surgeon (J.C.) in the Cataract Surgery Centre, Hong Kong Sanatorium and Hospital. All eyes were targeted for emmetropia and surgery was performed in the nondominant eye first. Simultaneous bilateral RLE was performed in patients who desired simultaneous bilateral surgery. Eyes with preexisting corneal astigmatism ⩾0.75 D were treated with limbal relaxing incisions. Patients with preexisting ocular conditions (eg, cataract) or systemic diseases (eg, diabetes mellitus) that might potentially affect the postoperative visual performance were excluded from the study.
The Tecnis acrylic multifocal IOL is a three-piece IOL with a biconvex design. The anterior surface is a wavefront aspheric design whereas the posterior is a diffractive surface with 29 concentric circles. The light entering the IOL is split equally into a distance and near focus (+4.00-D add) independent of pupil size.
Patients were scheduled for follow-up at 1 day, 1 week, and 1, 3, and 6 months postoperatively. A thorough functional visual assessment was performed at 6-month follow-up including monocular UDVA and CDVA, uncorrected intermediate visual acuity (UIVA) and distance-corrected intermediate visual acuity (DCIVA) at 67 cm, and uncorrected near visual acuity (UNVA) and distance-corrected near visual acuity (DCNVA) at 30 cm of the RLE eye. The Rosenbaum Pocket Vision Screener (Latham & Phillips Ophthalmic Products Inc, Grove City, Ohio) near visual acuity chart (for use at 35 cm) was used to test the visual acuity at both 67 cm and 30 cm. The actual visual acuity at its corresponding distance was calculated by the actual subtended visual angle. Subsequently, all data were converted into the logarithm of the minimum angle of resolution (logMAR) for statistical analysis. A written subjective questionnaire on visual symptoms such as halo, night glare, starburst, satisfaction with visual performance, and spectacle dependency was administered at 6-month follow-up. Patients were requested to score the severity of these symptoms by 0 (none), 1 (very mild), 2 (mild), 3 (moderate), 4 (severe), or 5 (very severe). Satisfaction with visual performance was scored by 1 (very dissatisfied), 2 (dissatisfied), 3 (neutral), 4 (satisfied), and 5 (highly satisfied). Patients were asked about the need for spectacles for distance vision (eg, driving) and computer and reading tasks. In addition, patients were asked whether they regretted having the surgery and if they would recommend this surgery to their friends.
The Wilcoxon signed-rank test was used to compare preoperative CDVA to postoperative CDVA. In a subgroup of patients who received unilateral RLE, UDVA, CDVA, and manifest spherical equivalent were compared between the RLE eyes and fellow eyes using the Mann-Whitney U test. The scores for halo, night glare, starburst, and satisfaction with visual performance obtained by the questionnaire were compared between: 1) unilateral and bilateral RLE; and 2) with and without habitual spectacle use before surgery using the Mann-Whitney U test. The satisfaction score was further compared among patients who had unilateral/bilateral RLE and with/without habitual spectacle use by the Kruskal-Wallis test. Results were presented as mean ±1 standard deviation. A two-tailed P value <.05 was considered statistically significant. All statistical analyses were performed using SPSS 16 (SPSS Inc, Chicago, Illinois).
The study cohort comprised 45 eyes from 29 patients. Unilateral RLE with ZMA00 was performed in 13 patients and bilateral RLE was performed in 16 patients. Simultaneous bilateral RLE was performed in 4 patients. The majority of patients were women (71%). Mean patient age was 55.3±5.5 years (range: 47 to 69 years). Ocular biometry and preoperative manifest refraction are presented in Table 1. Mean preoperative CDVA was −0.03±0.06 logMAR (20/19 Snellen). Mean near addition was 2.30±0.35 D (range: 1.50 to 2.75 D). Preoperatively, 14 (48%) patients did not wear spectacles except for near tasks (ie, no habitual spectacle use).
Table 1: Ocular Biometry and Manifest Refraction of Eyes That Underwent Refractive Lens Exchange
Mean postoperative manifest refraction is shown in Table 1 and Figure 1. Mean pre- (both eyes) and postoperative (RLE eyes only) manifest refractions of a subpopulation who received unilateral RLE are reported in Table A (available as supplemental material in the PDF version of this article). Manifest refraction was not performed in the fellow eyes postoperatively. The difference in mean manifest spherical equivalent between the RLE eyes at 6 months postoperative and the fellow eyes was 0.08 D (P=.369).
Figure 1. Manifest refraction spherical equivalent pre- and 6 months postoperative.
Limbal relaxing incision was performed in 9 (20%) eyes from 6 patients. Mean preoperative corneal astigmatism of these eyes was 1.28±0.43 D. At 6 months postoperative, the mean manifest astigmatism was 0.67±0.33 D. Postoperative corneal astigmatism data were not available because keratometry was not performed.
Postoperative Visual Outcomes at 6 Months
Uncorrected and distance-corrected visual acuity at distance, 67 cm, and 30 cm are presented in Table 2. Two eyes of the same patient from the bilateral RLE group were excluded from visual acuity analyses (n=43) due to posterior capsular opacity. At 6 months, no statistically significant difference was noted in CDVA compared to preoperative (P=.395). Visual acuity results are listed for distance (Fig 2), intermediate (Fig 3), and near (Fig 4).
Table 2: Postoperative Visual Acuity at Distance, Intermediate, and Near in 43 Eyes That Underwent Refractive Lens Exchange
Figure 2. Cumulative uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) at 6 months postoperative.
Figure 3. Cumulative uncorrected intermediate visual acuity (UIVA) and distance-corrected intermediate visual acuity (DCIVA) at 67 cm at 6 months postoperative.
Figure 4. Cumulative uncorrected near visual acuity (UNVA) and distance-corrected near visual acuity (DCNVA) at 30 cm at 6 months postoperative.
In a subgroup of patients who received unilateral RLE (n=13), UDVA and CDVA in the RLE and fellow eyes are reported in Table 2. Visual acuity was not measured in the fellow eyes postoperatively. Assuming that the visual acuity in the fellow eyes did not change during the study period, mean UDVA (P=.012) and mean CDVA (P=.029) were significantly worse in the RLE eyes than in the fellow eyes postoperatively. Ten (77%) of 13 patients had a worse UDVA in the RLE eye than the fellow eye postoperatively.
Complications, Safety, and Efficacy at 6 Months
Two intraoperative capsule-related complications occurred. One eye had posterior capsular tear, which necessitated placement of the IOL optic in the bag while the lens haptics were positioned in the sulcus. Corrected distance visual acuity decreased from 20/15 preoperatively to 20/20 postoperatively at 6 months. Another eye had a peripheral extension of the continuous curvilinear capsulorrhexis. No loss of CDVA was reported in this eye. Posterior capsular opacity was observed in one patient with bilateral RLE (2 eyes, 4%). This bilateral RLE patient had a loss of visual acuity from 20/20 to 20/25 in one eye and from 20/20 to 20/30 in the fellow eye at 6 months. The safety and efficacy ratios at 6 months postoperatively were 0.98±0.18 and 0.77±0.22, respectively.
Apart from the eyes with untreated posterior capsular opacity (2 eyes), 11 (26%) of 43 eyes experienced a 1 line loss of CDVA (Fig 5).
Figure 5. Corrected distance visual acuity (CDVA) change at 6 months postoperative. One eye with posterior capsular opacity lost 2 lines of CDVA.
Subjective Symptoms and Patient Satisfaction
Of 29 patients, 27 (93%) responded to the subjective questionnaire. As all bilateral RLE patients (n=15) who responded to the questionnaire did not report a difference in symptoms between the two eyes, the result was reported using patient as the unit instead of the number of eyes. From those who responded, the numbers of patients who experienced halo, night glare, and starburst were 21 (78%), 7 (26%), and 13 (48%), respectively. The overall mean scores of halo, night glare, and starburst were 2.26±1.53, 0.74±1.41, and 1.26±1.58, respectively (Table 3). The numbers of patients who experienced moderate to severe (ie, score ⩾3) halo, night glare, and starburst were 13 (48%), 4 (15%), and 6 (22%), respectively. The mean score for satisfaction with visual performance was 3.78±0.88. Nineteen (70%) patients were satisfied to highly satisfied (ie, score ⩾4) with their visual performance.
Table 3: Number of Symptomatic Patients With Respect to Refractive Lens Exchange and Preoperative Spectacle Dependence
The mean scores for halo, night glare, and starburst in the symptomatic patients and satisfaction with visual performance were plotted (Fig A [available as supplemental material in the PDF version of this article], Table 4) for patients who underwent unilateral or bilateral RLE with ZMA00 and for patients with or without habitual spectacle use preoperatively. No statistically significant differences in these scores were noted between groups (all P>.05).
Table 4: Patient Symptoms and Satisfaction With Visual Performance After Refractive Lens Exchange
Figure B (available as supplemental material in the PDF version of this article) shows the mean satisfaction score with visual performance in unilateral or bilateral RLE patients with or without habitual spectacle use preoperatively. No statistically significant difference was noted in the score among different groups (P=.911).
One (4%) unilateral RLE patient regretted having RLE surgery as she required spectacles all the time postoperatively. Her manifest refraction changed from +0.25 +0.25 × 170 (20/15) preoperatively to +0.25 +0.75 × 130 (20/20) 6 months postoperatively. She also experienced moderate (score=3) halo and starburst. A second unilateral RLE patient was uncertain whether she regretted having the surgery and was also uncertain if she would refer a friend for this surgery. This patient had to wear spectacles for computer and near tasks postoperatively. A third unilateral RLE patient said she would not refer her friends for this surgery as she had difficulty in driving in bad weather. Twenty-four (89%) patients said they had already referred or would refer their friends for the same RLE surgery. None of the patients requested explantation of the multifocal IOL.
At 6 months, none of the bilateral RLE patients (n=15, 10 computer users) required spectacles for distance, computer use, or reading. Six (50%) of 12 unilateral RLE patients (all computer users) required spectacles postoperatively. Two (17%) patients required spectacles at all distances. Three (25%) patients required spectacles for both computer use and reading and 1 (8%) patient required spectacles for computer use only.
This is the first study to report visual outcome and patient satisfaction after RLE with the ZMA00 multifocal IOL. Loss of CDVA due to complications was observed in one eye. Loss of CDVA in other eyes was idiopathic. The posterior capsular opacity rate of 4% at the early postoperative period is expected as the study cohort was relatively young (mean age 55.3 years). An association between a higher rate of posterior capsular opacity and a younger age (<60 years) has been reported by Baratz et al.2
The visual outcomes in our study are comparable with similar studies of RLE with diffractive multifocal IOLs.3,4 In a study using the ZM900 (Abbott Laboratories), an earlier silicone version of the ZMA00 for RLE, UDVA of 0.8 (20/25) or better was achieved in 89% of eyes (70% in our study) and UNVA better than J2 (20/25) was achieved in 85% of eyes at 6 months postoperatively3 (81% 20/30 or better at 30 cm in our study). In another study of ZM900 RLE, mean UDVA and UNVA (35 cm) were 0.087 and 0.133 logMAR at 6 months, respectively.4 Our study demonstrated a better UDVA of −0.10 logMAR but a slight decrease in UNVA of 0.18 logMAR. Goes4 also reported a mean binocular DCIVA of 0.29 logMAR at 60 cm. Mean monocular DCIVA at 67 cm was 0.40 logMAR in our study.
In a study with a large sample size (363 eyes) investigating the implantation of the ReSTOR SN60D3 (Alcon Laboratories Inc, Ft Worth, Texas) for cataract and RLE, Altaie et al5 reported 96.5% of eyes achieved UDVA of 6/12 (20/40) or better at 6 months, which is similar to the 93% in our study. In their study, Altaie et al5 reported UNVA of N5 (between 20/27 and 20/37) or better at 33 cm was achieved in 95% of eyes, whereas in our study, the same percentage of eyes could see 20/40 or better at 30 cm. The reduced near visual acuity in our study compared with previous reports can be explained by the fact that the near distance of 30 cm used in our study is not the optimal distance for ZMA00 near vergence. Theoretically, the best near distance for ZMA00 is 33 cm.6 Another group studied the visual outcomes of the ReSTOR SN60D3, SA60D3, and ZM900 and reported similar results, but better outcome was observed with the ZM900.7
In our study, overall spectacle independence was 78%. However, in bilateral RLE patients, it was 100%, and this result was superior to other bilateral RLE studies (93% to 96%).1,4 Visual disturbance, particularly halo, was experienced by the majority (78%) of patients, with moderate to severe symptoms reported by 48% of patients. The severity of visual symptoms was higher in unilateral RLE patients than bilateral RLE patients. One possible explanation for this phenomenon is that unilateral RLE patients are more aware of these conditions as the fellow eye is unaffected by these symptoms.
Patients without habitual spectacle use had greater complaints of night glare than those with habitual spectacle use. This is likely due to the fact that glare is uncommon in patients who do not wear spectacles compared to those who use contact lenses or spectacles.8
The outcomes of the current study indicate that unilateral RLE patients and patients without habitual spectacle use preoperatively were less satisfied with their visual performance than bilateral RLE patients or those who required habitual spectacle use. The dissatisfaction may be due to the reduced UDVA in the RLE eye than the unoperated fellow eye, residual refractive error, reduced quality of vision,9 or photic phenomena.10,11 Leccisotti12 studied the indications and incidence of secondary procedures after RLE for presbyopic correction with multifocal IOL in 52 patients with unilateral or bilateral RLE. He found that photorefractive keratectomy and IOL exchange were appropriate for preoperative emmetropes or low hyperopes only. The indications for these secondary procedures were residual refractive errors and halo.12 Interestingly, no bilateral RLE patients required lens exchange after the surgery.12 This concurs with our finding.
To avoid an unhappy RLE patient, the possible risk of loss in CDVA of 1 line should be discussed (it was 1 in 4 in our study). Alfonso et al1 reported that 11% of patients who underwent bilateral RLE with SN60D3 implantation experience 1 line loss in binocular CDVA. However, a loss of CDVA >1 line has not been reported.3,13 We also recommend demonstrating to the patient the position of the near focus for a more realistic expectation of the visual outcome.
Despite a high percentage of patients experiencing moderate to severe halo and some loss of vision, the overall satisfaction with visual performance was high. This outcome suggests that many patients are willing to sacrifice some of their existing “normal distance vision” for potential spectacle independence.
Our study had two primary limitations. First, we did not evaluate the preoperative intermediate and near visual acuity. Therefore, changes in visual acuity were not assessed postoperatively. Second, the subjective questionnaire used in this study did not assess the impact of visual symptoms on the quality of life of the patients.
Refractive lens exchange with the ZMA00 multifocal IOL is an option for presbyopia correction. Halo, night glare, and starburst are common but usually well tolerated. The most satisfied patients were those who underwent bilateral RLE with habitual spectacle use preoperatively.
- Alfonso JF, Fernández-Vega L, Valcárcel B, Ferrer-Blasco T, Montés-Micó R. Outcomes and patient satisfaction after presbyopic bilateral lens exchange with the ResTOR IOL in emmetropic patients. J Refract Surg. 2010;26(12):927–933. doi:10.3928/1081597X-20100114-01 [CrossRef]
- Baratz KH, Cook BE, Hodge DO. Probability of Nd:YAG laser capsulotomy after cataract surgery in Olmsted County, Minnesota. Am J Ophthalmol. 2001;131(2):161–166. doi:10.1016/S0002-9394(00)00795-9 [CrossRef]
- Barisic A, Dekaris I, Gabric N, et al. Comparison of diffractive and refractive multifocal intraocular lenses in presbyopia treatment. Coll Antropol. 2008;32(Suppl 2):27–31.
- Goes FJ. Refractive lens exchange with the diffractive multifocal Tecnis ZM900 intraocular lens. J Refract Surg. 2008;24(3):243–250.
- Altaie R, Ring CP, Morarji J, Patel DV, McGhee CN. Prospective analysis of visual outcomes using apodized, diffractive multifocal intraocular lenses following phacoemulsification for cataract or clear lens extraction. Clin Experiment Ophthalmol. 2012;40(2):148–154. doi:10.1111/j.1442-9071.2011.02671.x [CrossRef]
- Packer M, Chu YR, Waltz KL, et al. Evaluation of the aspheric tecnis multifocal intraocular lens: one-year results from the first cohort of the food and drug administration clinical trial. Am J Ophthalmol. 2010;149(4):577–584.e1. doi:10.1016/j.ajo.2009.10.022 [CrossRef]
- Ngo C, Singh M, Sng C, Loon S, Chan Y, Thean L. Visual acuity outcomes with SA60D3, SN60D3, and ZM900 multifocal IOL implantation after phacoemulsification. J Refract Surg. 2010;26(3):177–182. doi:10.3928/1081597X-20100224-03 [CrossRef]
- Allen RJ, Saleh GM, Litwin AS, Sciscio A, Beckingsale AB, Fitzke FW. Glare and halo with refractive correction. Clin Exp Optom. 2008;91(2):156–160. doi:10.1111/j.1444-0938.2007.00220.x [CrossRef]
- Shimizu K, Ito M. Dissatisfaction after bilateral multifocal intraocular lens implantation: an electrophysiology study. J Refract Surg. 2011;27(4):309–312.
- Woodward MA, Randleman JB, Stulting RD. Dissatisfaction after multifocal intraocular lens implantation. J Cataract Refract Surg. 2009;35(6):992–997. doi:10.1016/j.jcrs.2009.01.031 [CrossRef]
- de Vries NE, Webers CA, Touwslager WR, et al. Dissatisfaction after implantation of multifocal intraocular lenses. J Cataract Refract Surg. 2011;37(5):859–865. doi:10.1016/j.jcrs.2010.11.032 [CrossRef]
- Leccisotti A. Secondary procedures after presbyopic lens exchange. J Cataract Refract Surg. 2004;30(7):1461–1465. doi:10.1016/j.jcrs.2003.11.056 [CrossRef]
- Blaylock JF, Si Z, Aitchison S, Prescott C. Visual function and change in quality of life after bilateral refractive lens exchange with the ReSTOR multifocal intraocular lens. J Refract Surg. 2008;24(3):265–273.
Figure A. The mean scores of visual symptoms (in symptomatic patients) and satisfaction with visual performance for patients with unilateral and bilateral refractive lens exchange and with or without habitual spectacle use preoperatively. A higher visual symptom score indicates greater severity. A higher satisfaction score indicates greater satisfaction. Number in brackets indicates the sample size. Error bars indicate ±1 standard deviation.
Figure B. The mean satisfaction scores for visual performance for patients who had 1) unilateral refractive lens exchange (RLE) without habitual spectacle use, 2) bilateral RLE without habitual spectacle use, 3) unilateral RLE with habitual spectacle use, and 4) bilateral RLE with habitual spectacle use preoperatively. Number in brackets indicates the sample size. Error bars indicate ±1 standard deviation.
Ocular Biometry and Manifest Refraction of Eyes That Underwent Refractive Lens Exchange
|Preoperative biometry (n=45)|
| Axial length (mm)||23.63±1.49 (21.38 to 28.61)|
| ACD (mm)||3.07±0.36 (2.35 to 3.88)|
| Average K (D)||44.05±1.65 (40.06 to 48.44)|
| Corneal astigmatism (D)||0.61±0.45 (0 to +1.87)|
|Preoperative manifest refraction (n=44)*|
| Sphere (D)||−0.55±3.56 (−13.51 to +3.00)|
| Cylinder (D)||+0.45±0.40 (0 to +1.50)|
| Spherical equivalent (D)||−0.32±3.56 (−13.13 to +3.63)|
|Postoperative manifest refraction (n=45)|
| Sphere (D)||+0.04±0.49 (−1.25 to +1.00)|
| Cylinder (D)||+0.42±0.30 (0 to +1.25)|
| Spherical equivalent (D)||+0.25±0.52 (−1.00 to +1.25)|
Postoperative Visual Acuity at Distance, Intermediate, and Near in 43 Eyes That Underwent Refractive Lens Exchange
|Visual Acuity||logMAR (Snellen Equivalent)|
|Distance||67 cm||30 cm|
|Uncorrected||−0.10±0.13 (20/22)||0.43±0.25 (20/31)||0.18±0.05 (20/24)|
|Distance-corrected||−0.02±0.06 (20/20)||−0.40±0.21 (20/30)||0.17±0.02 (20/24)|
Number of Symptomatic Patients With Respect to Refractive Lens Exchange and Preoperative Spectacle Dependence
|Symptoms||No. of Patients (%)|
|Unilateral RLE (n=12)||Bilateral RLE (n=15)||With Habitual Spectacle Use (n=15)||Without Habitual Spectacle Use (n=12)|
|Halo||8 (67)||13 (87)||12 (80)||9 (75)|
|Night glare||2 (17)||5 (33)||4 (27)||3 (25)|
|Starburst||7 (58)||6 (40)||6 (40)||7 (58)|
Patient Symptoms and Satisfaction With Visual Performance After Refractive Lens Exchange
|Symptoms||Mean Score||PValue*||Mean Score||PValue*|
|Unilateral RLE (n=12)||Bilateral RLE (n=15)||With Habitual Spectacle Use (n=15)||Without Habitual Spectacle Use (n=12)|