Cataract surgery is effective in restoring visual clarity and distance vision. However, standard monofocal intraocular lenses (IOLs) have a fixed refractive power, leaving patients presbyopic and dependent on spectacles for near vision, even after surgery.1 Various techniques to correct postoperative presbyopia have been tested with limited success.2 New lens-refilling procedures are currently under investigation in animal models; however, problems such as leakage of the injectable material from the capsular bag and formation of posterior capsule opacification (PCO) must be overcome.3 Multifocal IOLs attempt to divide light into multifocal points to mimic accommodation; however, these IOLs often reduce contrast sensitivity and result in unwanted optical phenomena, such as glare.4
Accommodating IOLs were developed in an attempt to restore the accommodative properties in the pseudophakic eye. Accommodating IOLs use the optic-shift concept and transform the forces of the ciliary muscle into a forward shift of the IOL optic to focus on intermediate and near images, thus mimicking the eye's natural process of accommodation.4 Because many patients who have cataract surgery with currently available IOLs report difficulty with near vision, accommodating IOLs are being used to correct postoperative presbyopia and improve near and distance vision without the aid of spectacles. Several types of accommodating IOLs are commercially available today. These include the 1CU (HumanOptics), BioComFold (Morcher), Tetraflex (Lenstec), Synchrony (Visiogen), and Crystalens AT-45 (Eyeonics, Inc).4 As of 2006, the Crystalens is the only accommodating IOL available in the United States.5
Despite many studies seeking to characterize the function and effectiveness of accommodating IOLs, it remains unclear whether accommodating IOLs truly restore accommodation in cataract surgery patients. We performed a metaanalysis of randomized controlled trials to characterize the functional performance of accommodating IOLs versus that of standard monofocal IOLs by analyzing visual acuity, pilocarpine-induced IOL shift, other secondary outcomes (eg, spectacle independence), and potential adverse effects. The results in this metaanalysis can inform patients and clinicians of the effectiveness and safety of accommodating IOLs implanted during cataract surgery.
MATERIALS AND METHODS
Databases, Search Terms, and Limits
Searches in Medline (1950 to 2008) and the Cochrane Library (The Cochrane Library 2008, Issue 3) were performed from September to October 2008. In each database, the results of intraocular lens-related and accommodation-related terms were combined. Appendix A shows the complete search strategies. No limits were used. This study was not a Cochrane review. References in relevant articles were manually reviewed for articles not identified by the electronic search; clinicaltrials.gov was also searched (October 2008) for unpublished or ongoing work.
Studies were considered for inclusion if they were randomized controlled trials that compared accommodating IOLs and standard monofocal IOLs in cataract surgery patients. Only studies with patients 19 years or older were considered for evaluation because congenital cataract can involve different mechanisms and treatments. Two independent reviewers separately evaluated studies based on inclusion criteria, and discrepancies were resolved by consensus.
Two independent reviewers extracted data with a standardized data-collection form; disagreements were resolved by discussion. An attempt was made to obtain missing data by contacting authors directly. When there was more than 1 published report of the same population, data were extracted from both articles; however, the data from the longest period of follow-up was used in the analysis.
A modified version of the van Tulder et al.6 criteria list was used to assess the quality and validity of the studies. The list was made up of 10 questions related to randomization, allocation concealment, blinding, dropout rates, baseline patient characteristics, and intention-to-treat analysis (Appendix B). In the original van Tulder et al.6 criteria, there were 11 questions, and each question was scored as yes (+1), no (−1), or do not know (0), with a maximum score of 11. However, the provider-masked criterion (criterion E) was not included because it is not possible to blind the surgeon performing the operation. In addition, scores of 0 were assigned to criteria that were reported as “no” or were not specifically reported to avoid additional penalties for studies that were comprehensive in reporting inability to meet quality criteria. Two independent reviewers scored the studies, and discrepancies were resolved by consensus. The quality-assessment scale was incorporated to possibly explain differences in results between studies as well as to analyze subgroups in studies above a methodologic cut-point (ie, explicit description of 2 or more of the following: concealment of treatment allocation, such as with sealed envelopes; dropout rate; blinding of patients; blinding of outcome assessor) in a sensitivity analysis. Van Tulder et al. also suggest that an arbitrary composite score of 6 (>50% fulfillment of criteria) be used to define a study of adequate quality.
Distance-corrected near visual acuity (DCNVA) was chosen as the primary outcome because it is a standard subjective measure of accommodative ability of the eye to focus on near objects.1 The secondary outcomes were (1) pilocarpine-induced anterior chamber displacements to determine the extent of optical shifts induced by accommodation in pseudophakic eyes7 because anterior optic displacement and a concomitant shift in the focal plane theoretically lead to true pseudophakic accommodation, (2) reading speed, (3) glare, (4) contrast sensitivity, (5) spectacle independence, and (6) any adverse effects noted, for example posterior capsule opacification (PCO), which is an emerging concern in accommodating IOL implantation.8
Quantitative Data Synthesis
Summary Measure Used for Dichotomous and Continuous Variables
Due to variations in measurement scales, DCNVA outcomes were pooled using standardized mean differences with 95% confidence intervals (CIs) and pilocarpine-induced displacement of the lens was pooled using weighted mean differences with 95% CIs. For other secondary outcomes, such as glare and PCO rates, qualitative measures were used for comparison because not enough studies reported consistently on the rates in each group to perform a statistical analysis. A table was created of studies that mentioned the outcomes for PCO rates, glare, contrast sensitivity, spectacle independence, and reading speed. The quantitative data (when available) and the qualitative description of the outcomes were assessed to generate a pooled summary, from which a composite descriptive conclusion was drawn using the following qualitative categories: favoring accommodating IOLs, no difference between the 2 IOLs, or favoring standard monofocal IOLs.
Fixed Versus Random Effects
A random-effects model was used for the outcomes summarized quantitatively in Revman5 software (version 5.0, Nordic Cochrane Centre, The Cochrane Collaboration) because it was assumed that the studies being combined were estimating treatment effects that followed a distribution across studies.
Handling Missing Data Despite Efforts to Obtain Data
For missing data that could not be obtained from the published reports or author communication, an attempt was made to calculate or estimate values (eg, standard deviations, mean age of combined groups, mean treatment effects) using the formulas supplied in the Cochrane handbook.9 Studies were excluded from the metaanalysis portion of the review when values for missing data could not be obtained or estimated.
Study heterogeneity was assessed by performing an I2 test included in the software used for the random-effects model. The I2 test is a method for quantifying inconsistency across studies and describes the percentage of variability in effect estimates that is due to heterogeneity rather than to chance. A value greater than 50% is considered substantial heterogeneity. When there was substantial heterogeneity, the results in the individual studies were evaluated in an effort to identify the study or studies responsible. Then, the characteristics of any study or studies with outlying results were evaluated to determine whether an explanation could be identified. Sensitivity analyses were performed in an effort to identify the largest group of studies that passed the test of heterogeneity. In each case, the results included all studies as well as the results in the largest group of homogeneous studies.
To evaluate the effect of methodologic quality on the summary estimates, 2 sensitivity analyses were performed using the van Tulder et al.6 quality assessment scale. In the first, the analysis was restricted to studies that specifically fulfilled 2 of the following 5 criteria: an adequate allocation concealment method, loss to follow-up lower than 30%, blinding of patients, blinding of outcome assessor, and use of intention-to-treat analysis.6 Inadequate allocation concealment and inadequate blinding (of patients and outcome assessors) are the quality criteria with the empirical evidence of an association with the risk for biased outcomes.10 The second analysis was restricted to studies with van Tulder et al. summary quality scores of 6 or higher, an arbitrarily defined cutoff score suggested by van Tulder et al.6
To evaluate the effect of study characteristics on the summary estimates, sensitivity analyses were also performed. The analyses were based on the longest reported length of follow-up, the type of IOLs studied, the study location, monocular IOL versus binocular IOL implantation, fellow-eye versus interpatient-eye comparisons, and measurement scales (Jaeger versus logMAR).
A funnel plot was used for the primary outcome of DCNVA to assess for publication bias. Publication bias is less of a concern when the plot is funnel shaped with the apex near the summary estimate. A strong correlation between sample size and summary estimates suggests publication bias.
Description of Studies
Results of Search
The search strategy generated 451 potentially relevant studies. Figure 1 shows a flow diagram of the included and excluded studies. Of the 14 randomized controlled trials that were potentially appropriate for analysis, 2 studies11,12 were removed because the published report could not be accessed or the author could not be contacted. This left 12 randomized controlled trials in the metaanalysis.
Characteristics of Included Studies
Table 1 shows the 12 randomized trials13–24 that met all inclusion criteria; the combined number of eyes in the studies was 727. The studies were performed in a variety of countries, and the study size ranged from 22 to 180 eyes. The mean patient age ranged from 62 to 76; 37.5% to 53.3% of patients were men. Most studies used the 1CU accommodating IOL, although several used the BioComFold, Crystalens AT-45, or KH-3500 (Lenstec) IOL. Comparisons were all with monofocal IOLs of varying brands. The duration of follow-up ranged from 4 weeks to 3 years, with most being at least 1 year. Attrition was significantly high (>30%) in 316,20,23 of the 7 studies that reported dropout rates. Only 3 trials reported using more than 1 blinding method (examiner- and patient-masked).14,15,24
Quality of Methodology
Table 2 shows the 4 studies 14,15,22,24 that met the first quality-assessment criterion of having 2 or more of the following: adequate allocation concealment, blinding (patient, outcome assessor), loss to follow-up lower than 30%, and reported use of intention-to-treat analysis. Four studies14,15,22,24 were above the second criterion of having a quality-assessment score cutoff of 6. The van Tulder et al.6 scores ranged from 4 to 9 out of a total possible 10. Most studies did not report explicitly whether they had used adequate treatment-allocation concealment, and many failed to report what blinding methods, if any, were used. Lack of allocation concealment precludes full assessment of the risk for attribution bias. Many studies did not report dropout rates. Four15,17,22,24 of the 7 studies that did report dropout rates were deemed to have significant loss to follow-up (>30%). These factors raised concerns that (1) the lack of allocation concealment introduces selection bias, (2) the lack of blinding makes performance and detection bias a concern, (3) attrition bias is a potential issue with large loss to follow-up, (4) and the lack of intention-to-treat analysis disturbs the preservation of randomization.
Primary Efficacy Outcome: Distance-Corrected Near Visual Acuity
Based on 10 trials of 508 eyes,14–18,20–22,24 accommodating IOLs improved DCNVA more than monofocal IOLs; the standardized mean difference was −1.36 (95% CI, −2.22 to −0.49); however, the substantial heterogeneity across studies (I2 = 94%) could not be explained by any characteristic of the study population or methodology (Figure 2). Pooling the 6 homogeneous trials (I2 = 43%) of 179 total eyes showed no significant difference in DCNVA; the standardized mean difference was −0.16 (95% CI, −0.56 to 0.25) (Figure 2).
Secondary Efficacy Outcomes: Pilocarpine-Induced Intraocular Lens Shift
Based on 4 studies (182 total eyes) that evaluated pilocarpine-induced IOL shift,13,15,17,20 accommodating IOLs were associated with significantly greater anterior lens shift than monofocal IOLs; the weighted mean difference was −0.36 (95% CI, −0.47 to −0.24) (Figure 3), although the studies were heterogeneous (I2 = 58%). Heterogeneity was not explained by the sensitivity analyses.
Other Secondary Efficacy Outcomes
Table 3 shows the following secondary outcomes used to assess functionality of accommodating IOLs versus monofocal IOLs: glare, contrast sensitivity, reading speed, and spectacle independence. However, the reporting of these outcome measures was not consistent between studies; no more than 2 studies reported each outcome. Based on the analysis, there was no statistically significant difference in glare18,24 or contrast sensitivity18,21 between the 2 IOL groups. The few studies that reported reading speed16,24 and spectacle independence24 found these measures to be qualitatively better in the accommodating IOL group than in the monofocal IOL group.
Posterior capsule opacification was the most commonly reported adverse effect reported in the studies. Four of the 5 studies that mentioned PCO14,16,19,23,24 reported increased rates in the accommodating IOL group several months postoperatively (Table 4). Of note, 1 study17 reported anterior chamber hemorrhage and another,15 posterior capsule shrinkage.
Sensitivity and Subgroup Analyses
More than 10 sensitivity analyses were performed to determine the source of heterogeneity in the DCNVA trials. However, the source of heterogeneity could not be determined.
The funnel plot showed no correlation between study size and effect size or any other evidence of publication bias.
The findings in our metaanalysis of 12 randomized controlled trials comparing accommodating IOLs and monofocal IOLs require careful interpretation. The primary measure of subjective efficacy, DCNVA, provided different results depending on how the data were analyzed. Including all 10 trials used in the metaanalysis of this outcome resulted in a statistically significant improvement in DCNVA; however, the pooled finding was based on study results that differed substantially beyond what would be expected to result from chance. On the other hand, when the analysis was limited to the largest group of homogenous studies that could be identified, the pooled finding was no longer significant. Exclusion of the remaining 4 trials could not be justified by any shared characteristics of quality, population, or study design. Other subjective measures of efficacy, such as spectacle independence and reading speeds,16,24 favored accommodating IOLs, whereas there was no difference in glare and contrast sensitivity.18,21,24 No secondary measure of efficacy was reported by more than 3 studies. The single objective measure, pilocarpine-induced anterior shift, consistently favored the accommodating IOLs; however, the clinical relevance of the findings was unclear.
With regard to adverse effects, PCO consistently emerged as an important complication of accommodating IOLs. Of the 5 studies that mentioned PCO, 4 reported increased rates several months postoperatively. Increased PCO rates in accommodating IOLs may be explained by the breach in the square-edged barrier to the IOL optic.20 Studies have shown that square-edged barriers are critical in preventing PCO formation.25 Other possible explanations point to differences in IOL materials. The 1CU accommodating IOL is hydrophilic, while many monofocal IOLs are hydrophobic; the hydrophilic nature of this accommodating IOL is thought to increase risk for developing visually significant PCO over time.25–27
Subjective measurements of near visual acuity are often the most readily available means of evaluating accommodation.1 Objective measurement techniques, such as measuring the true dioptric refractive change as eyes focus from distance to near, should ideally be used in conjunction with subjective tests to provide possible explanations for the presence or absence of subjective improvements; however, many studies do not include the true dioptric refractive change as a part of the evaluation. These measurements can be performed by any objective optometer, autorefractor, or wavefront aberrometer that allows patients to focus on near or distant objects. However, objective measurements of accommodation in pseudophakic eyes are complicated by spurious reflections and stray light cause by the high refractive indices of the IOLs; this results in bright Purkinje III images reflecting off the anterior surface of the IOL.1 In addition, it is unclear whether 1 of the objective measures analyzed in our study (pilocarpine-induced ciliary muscle contraction) is a good real-life model of everyday accommodation.15 There is concern that pilocarpine acts as a supra-stimulus to the IOL, causing more pronounced thickening and net forward movement than in physiologic stimulation. It is clear that more standardized methodologies for objective measures of accommodation in pseudophakic patients are needed and that both subjective and objective measurements must be incorporated in clinical reviews. The United States Food and Drug Administration recently mandated that clinical trials combine subjective measurements and objective measurements as evidence of restoration of accommodation.1
Regarding quality of the evidence, although all 12 studies (727 total eyes) in this review were randomized trials, only 1 study15 allowed assessment of the adequacy of allocation concealment. In addition, although the characteristics of each trial's study arms appeared to be well balanced at baseline, at least 4 trials15,17,22,24 had a high attrition rate and no trial reported using an intention-to-treat analysis. This raises a concern that the intent of the randomization to balance potentially confounding variables could have been jeopardized. Performance bias is also a concern; only 3 trials reported using patient and outcome assessor blinding to reduce bias. 14,15,24 Last, only 6 studies16,19,20,22–24 had a follow-up longer than 12 months, which may not be adequate for proper integration of cortical and subcortical functions to enable accommodation. Neuroadaptive responses in presbyopia have yet to be extensively studied; some experts believe it is not unreasonable to wait up to 1 year for the necessary neuroadaptation involved in accommodation.28 Furthermore, recent reports show the effect of motivation in accommodation, especially related to adaptation of reading. Leydolt et al.29 found that near-vision training protocols were associated with higher rates of spectacle independence. Overall, the studies included were of moderate to good quality, although there is still adequate reason for concern of systematic bias.
A main limitation of this review was the substantial heterogeneity between the studies. The 6 most homogenous studies were pooled for statistical analysis. We failed to explain the heterogeneity by 10 or more sensitivity analyses of study characteristics or methodologies (eg, quality assessment, length of follow-up, type of IOL, bilateral versus unilateral implantation, study location, measurement methods) and still cannot explain the heterogeneity.
Another possible limitation of our review is that to convert different DCNVA units to a uniform measure, we had to use standardized mean differences to synthesize the results. This limited our ability to communicate the clinical significance of any observed improvement in DCNVA when all trials were pooled. Other possible sources of bias in our review include not blinding reviewers, which proved impractical with 112 full articles reviewed; missing data in several studies; and the possibility of missed relevant published studies. This study was performed entirely at Dartmouth and was not registered as a Cochrane review before its initiation.
Pooling all data in the metaanalysis showed slight to moderate improvement in DCNVA with accommodating IOLs, which was reported by Findl and Leydolt in 2007.4 However, there was significant statistical heterogeneity between the trials, which makes pooling all trials methodologically problematic. When the homogeneous trials were pooled, there was no difference in DCNVA between accommodating IOLs and monofocal IOLs. Our review adds to the discussion by including additional randomized controlled trials and additional statistical analyses and by addressing important secondary efficacy measures (eg, reading speed, contrast sensitivity) and adverse effects (eg, glare, PCO). In a previous metaanalysis, Findl and Leydolt4 included 6 published randomized controlled trials. We included 6 additional randomized controlled trials in our systematic review.18,19,21,22–24 We identified additional studies by expanding our search strategies to clinicaltrials.gov and manual reference searches. Two randomized controlled trials22,24 were published after submission of the 2007 review and were included in our review. Dogru et al.19 used a matched-pair randomized design; their trial was included in the previous review as a nonrandomized study.
Regarding implications for practice, pooling all metaanalysis data showed slight to moderate improvement in DCNVA with accommodating IOLs, but no difference when pooling homogeneous trials. Finally, there seemed to be an increased rate of PCO with accommodating IOLs compared with the rate with monofocal IOLs, and patients should be fully informed about the risks and benefits before choosing this relatively new type of IOL.
In terms of implications for research, our findings were similar to those in the previous review by Findl and Leydolt,4 although ours included additional randomized controlled trials, efficacy measures, and statistical analysis. Further patient- and examiner-masked randomized controlled trials with adequate duration are needed; these trials should use standardized methodologies for measuring visual acuity and accommodating functions in pseudophakic patients. The source of heterogeneity in these studies would be an interesting question to explore as more studies are performed. In addition, these trials should evaluate the potential adverse effects of accommodating IOLs, such as PCO and cost effectiveness, to clarify tradeoffs when decisions regarding the clinical use of this type of IOL are being made.
1. Glasser A. Restoration of accommodation: surgical options for correction of presbyopia. Clin Exp Optom. 2008;91:279-295.
2. Glasser A. Restoration of accommodation. Curr Opin Ophthalmol. 2006;17:12-18.
3. Nishi Y, Mireskandari K, Khaw P, Findl O. Lens refilling to restore accommodation. J Cataract Refract Surg. 2009;35:374-382.
4. Findl O, Leydolt C. Meta-analysis of accommodating intraocular lenses. J Cataract Refract Surg. 2007;33:522-527.
5. Cumming JS, Colvard DM, Dell SJ, Doane J, Fine IH, Hoffman RS, Packer M, Slade SG. Clinical evaluation of the Crystalens AT-45 accommodating intraocular lens: results of the U.S. Food and Drug Administration clinical trial. J Cataract Refract Surg. 2006;32:812-825.
6. van Tulder M, Furlan A, Bombardier C, Bouter L. Updated method guidelines for systematic reviews in the Cochrane Collaboration Back Review Group; the Editorial Board of the Cochrane Collaboration Back Review Group. Spine. 2003;28(12):1290-1299.
7. Kriechbaum K, Findl O, Koeppl C, Menapace R, Drexler W. Stimulus-driven versus pilocarpine-induced biometric changes in pseudophakic eyes. Ophthalmology. 2005;112:453-459.
8. Beiko G. Status of accommodative intraocular lenses. Curr Opin Ophthalmol. 2007;18:74-79.
9. Higgins JPT, Green S, eds. Assessment of study quality. Cochrane Handbook for Systematic Reviews of Interventions 4.2.6 [updated September 2006]; Section 6. In: The Cochrane Library, Issue 4, 2006. Chichester, UK, John Wiley & Sons, Ltd
10. Schulz KF, Chalmers I, Hayes RJ, Altman DG. Empirical evidence of bias; dimensions of methodological quality associated with estimates of treatment effects in controlled trials. JAMA. 1995;273:408-412.
11. Wang C-Y, Ma B, Wang L-L. [Clinical accommodative status study of the accommodative foldable intraocular lens]. (Chinese) Guoji Yanke Zazhi. 2005;5:669-671.
12. Xu M, Li WS, Zhao YE, Wang QM. [The clinical efficacy of accommodative intraocular lens and multifocal intraocular lens in pseudophakic after phacoemulsification]. (Chinese) Zhonghua Yan Ke Za Zhi. 2007;43(2):104-107.
13. Legeais JM, Werner L, Abenhaim A, Renard G. Pseudoaccommodation: BioComFold versus a foldable silicone intraocular lens. J Cataract Refract Surg. 1999;25:262-267.
14. Mastropasqua L, Toto L, Nubile M, Falconio G, Ballone E. Clinical study of the 1CU accommodating intraocular lens. J Cataract Refract Surg. 2003;29:1307-1312.
15. Findl O, Kriechbaum K, Menapace R, Koeppl C, Sacu S, Wirtitsch M, Buehl W, Drexler W. Laserinterferometric assessment of pilocarpine-induced movement of an accommodating intraocular lens; a randomized trial. Ophthalmology. 2004;111:1515-1521.
16. Heatley CJ, Spalton DJ, Hancox J, Kumar A, Marshall J. Fellow eye comparison between the 1CU accommodative intraocular lens and the AcrySof MA30 monofocal intraocular lens. Am J Ophthalmol. 2005;140:207-213.
17. Sauder G, Degenring RF, Kamppeter B, Hugger P. Potential of the 1 CU accommodative intraocular lens. Br J Ophthalmol. 89. 2005. 1289-1292. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1772858/pdf/bjo08901289.pdf
. Accessed November 16, 2009.
18. Kamppeter BA, Sauder G, Jonas JB. Contrast and glare sensitivity after implantation of AcrySof and Human Optics 1CU intraocular lenses. Eur J Ophthalmol. 2005;15:458-461.
19. Dogru M, Honda R, Omoto M, Toda I, Fujishima H, Arai H, Matsuyama M, Nishijima S, Hida Y, Yagi Y, Tsubota K. Early visual results with the 1CU accommodating intraocular lens. J Cataract Refract Surg. 2005;31:895-902.
20. Hancox J, Spalton D, Heatley C, Jayaram H, Marshall J. Objective measurement of intraocular lens movement and dioptric change with a focus shift accommodating intraocular lens. J Cataract Refract Surg. 2006;32:1098-1103.
21. Wolffsohn JS, Naroo SA, Motwani NK, Shah S, Hunt OA, Mantry S, Sira M, Cunliffe IA, Benson MT. Subjective and objective performance of the Lenstec KH-3500 “accommodative” intraocular lens. Br J Ophthalmol. 90. 2006. 693-696. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1860198/pdf/693.pdf
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22. Marchini G, Mora P, Pedrotti E, Manzotti F, Aldigeri R, Gandolfi SA. Functional assessment of two different accommodative intraocular lenses compared with a monofocal intraocular lens. Ophthalmology. 2007;114:2038-2043.
23. Hancox J, Spalton D, Heatley C, Jayaram H, Yip J, Boyce J, Marshall J. Fellow-eye comparison of posterior capsule opacification rates after implantation of 1CU accommodating and AcrySof MA30 monofocal intraocular lenses. J Cataract Refract Surg. 2007;33:413-417.
24. Harman FE, Maling S, Kampougeris G, Langan L, Khan I, Lee N, Bloom PA. Comparing the 1CU accommodative, multifocal, and monofocal intraocular lenses; a randomized trial. Ophthalmology. 2008;115:993-1001.
25. Buehl W, Findl O. Effect of intraocular lens design on posterior capsule opacification. J Cataract Refract Surg. 2008;34:1976-1985.
26. Ursell PG, Spalton DJ, Pande MV, Hollick EJ, Barman S, Boyce J, Tilling K. Relationship between intraocular lens biomaterials and posterior capsule opacification. J Cataract Refract Surg. 1998;24:352-360.
27. Auffarth GU, Brezin A, Caporossi A, Lafuma A, Mendicute J, Berdeaux G, Smith AF. Comparison of Nd:YAG capsulotomy rates following phacoemulsification with implantation of PMMA, silicone, or acrylic intra-ocular lenses in four European countries; European PCO Study Group. Ophthalmic Epidemiol. 2004;11:319-329.
28. Pepin SM. Neuroadaptation of presbyopia-correcting intraocular lenses. Curr Opin Ophthalmol. 2008;19:10-12.
29. Leydolt C, Neumayer T, Prinz A, Findl O. Effect of patient motivation on near vision in pseudophakic patients. Am J Ophthalmol. 2009;147:398-405.
For Medline (performed 10/6/08)
#3Search #1 and #213:53:06 378
#1Search intraocular lens 13:52:5116 716
Intraocular Lens–Related Terms
“lenses, intraocular” [MeSH Terms] OR (“lenses” [All Fields] AND “intraocular” [All Fields]) OR “intraocular lenses” [All Fields] OR (“intraocular” [All Fields] AND “lens” [All Fields]) OR “intraocular lens” [All Fields]
“accommodation, ocular” [MeSH Terms] OR (“accommodation” [All Fields] AND “ocular” [All Fields]) OR “ocular accommodation” [All Fields] OR “accommodation” [All Fields]
For Cochrane Library(performed 10/7/08)
Searched entire library with search terms: “accommodation” AND “intraocular lens,” which resulted in 22 studies
Search terms: KEYWORD “cataracts” and INTERVENTION “intraocular lens” resulted in 51 studies.
Descriptions for van Tulder et al.6Criteria
A Was the method of randomization adequate?
B Was the treatment allocation concealed?
C Were the groups similar at baseline regarding the most importan prognostic indicators?
D Was the patient blinded to the intervention?
E Was the care provider blinded to the intervention?
F Was the outcome assessor blinded to the intervention?
G Were co-interventions avoided or similar?
H Was the compliance acceptable in all groups?
I Was the dropout rate described and acceptable?
J Was the timing of the outcome assessment in all groups similar?
K Did the analysis include an intention-to-treat analysis?
Possible responses for all criteria were yes, no, or don't know.