Methodological quality of the review: Medium confidence
Author: Liu J, Dong Y, Wang Y.
Region: Unites States of America (USA), Italy, Germany, Spain, Portugal and Italy
Equity focus: Not stated
Review type: Other review
Quantitative synthesis method: Meta-analysis
Qualitative synthesis method: Not applicable
Monofocal intraocular lenses (IOLs) are the most commonly implanted IOLs in cataract surgery. With a single focal point, monofocal IOLs are effective in restoring satisfactory distance vision; however, most patients require spectacle correction for intermediate and near vision, even after surgery. Thus, multifocal IOLs were designed to meet the increasing demand from patients for spectacle independence. More recently, a new-concept IOL was introduced based on extended depth of focus (EDOF) technology. The basic principle behind EDOF IOLs is to create a single elongated focal point to enhance the depth of focus or range of vision.
This study aims to evaluate the efficacy and safety of extended depth of focus (EDOF) intraocular lenses (IOLs) in cataract surgery.
In total, authors included nine studies in the meta-analysis. Of these, three were randomised controlled trials and six were non-randomised controlled trials with a total of 1,336 eyes. Three studies were conducted in Italy, two studies were conducted in Spain, and one study each was conducted in France, USA, Portugal and Germany. Based on Jadad scores, two of the three RCTs were scored higher than three points. All six non-randomised controlled trials were of relatively low risk of bias, scoring higher than six points.
Findings reported by the authors on:
Binocular uncorrected visual acuity:
Compared with monofocal IOLs, EDOF IOLs provided comparable UDVA (WMD: 0.01, 95% CI: − 0.06 to 0.08, P=0.81), better UIVA (WMD: -0.17, 95%CI: − 0.26 to − 0.08, P=0.0001) and better UNVA (WMD: -0.17, 95% CI: − 0.21 to − 0.12, P<0.00001). Compared with trifocal IOLs, EDOF IOLs showed no significant differences in UDVA (WMD: -0.01, 95% CI: − 0.03 to 0.01, P=0.34) or UIVA (WMD: -0.03, 95% CI: − 0.07 to 0.01, P=0.12) and performed worse in UNVA (WMD: 0.10, 95% CI: 0.07 to 0.13, P<0.0001). In sensitivity analysis, no single study significantly changed the pooled estimate, indicating that the results were stable.
Monofocal, EDOF and trifocal IOLs sustained 0.2 logMAR or better mean VA through 1.0 D, 2.0 D and 3.0 D, respectively. VA was significantly better with EDOF IOLs than with monofocal IOLs in the defocus levels from -1.0 to -4.0 D. VA was significantly better in trifocal IOL group than in EDOF IOL group from -2.5 to -4.0 D. The sensitivity analysis showed that no single study significantly changed the pooled estimate, indicating the results of defocus curves were stable.
Authors also found that EDOF IOLs resulted in reduced contrast sensitivity, more frequent halos, however, higher spectacle independence (RR: 2.81, 95% CI: 1.06 to 7.46, P=0.04) than monofocal IOLs. Compared with trifocal IOLs, EDOF IOLs produced worse near visual acuity (MD: 0.10, 95% CI: 0.07 to 0.13, P<0.0001). EDOF IOLs performed better than trifocal IOls in contrast sensitivity, and there were no significant differences in halos and spectacle independence. Serious postoperative complications were rare, with no adverse events reported in most studies.
Authors concluded that increasing the risk of contrast reduction and more frequent halos, EDOF IOLs provided better intermediate and near VAs than monofocal IOLs. At the expense of near vision, patients receiving EDOF IOLs have better contrast sensitivity than those receiving trifocal IOLs. Halo incidence and spectacle independence of EDOF IOLs were similar to those of trifocal IOLs.
Authors searched the PubMed, Embase, Web of Science, ClinicalTrials.gov and Cochrane Library databases (most recently updated in January 2019). No language limitations were applied in the search strategy. In addition, the references of identified articles and reviews were checked and matching publications were included. Authors included all clinical controlled studies (randomised or non-randomised, from 2000 to January 2019) comparing clinical outcomes of EDOF IOLs with those of control IOLs in patients undergoing cataract surgery.
The Jadad and Newcastle-Ottawa Scale (NOS) were used to assess the quality of randomised controlled trials (RCTs) and NRCSs, respectively. Primary outcomes included binocular uncorrected distance visual acuity (UDVA), uncorrected intermediate visual acuity (UIVA), uncorrected near visual acuity (UNVA), defocus curves and contrast sensitivity.
Authors used RevMan software to analyse the data. The weighted mean difference (WMD) and risk ratio (RR) with 95% confidence interval (CI) were calculated for continuous and dichotomous variables, respectively. A P-value <0.05 was defined as statistically significant. Forest plots were used to present the results. To verify the stability of the results, authors performed sensitivity analysis by individually omitting the included studies. Publication bias was measured visually using funnel plots. Statistical heterogeneity was tested by I2 tests.
Authors do not discuss generalisability of findings within the review, however, they mention that between-study heterogeneity was substantial in terms of length of follow-up, types of IOLs in the control group, study location and measurement methods.
The review does not include studies conducted in low and middle income countries and authors do not discuss the applicability of findings to these settings.
Summary of quality assessment:
Overall, medium confidence was attributed to the conclusions about the effects of the intervention, as important limitations were identified. Although authors used rigorous methods to pool data of included studies, authors did not conduct a thorough search of the literature to ensure that all relevant studies were included in the review.
Liu J, Dong Y, Wang Y. Efficacy and safety of extended depth of focus intraocular lenses in cataract surgery: a systematic review and meta-analysis. BMC Ophthalmol. 2019 Sep 2;19(1):198.