Comparison of patient outcomes following implantation of trifocal and extended depth of focus intraocular lenses: a systematic review and meta-Analysis

Author: Guo Y, Wang Y, Hao R, Jiang X, Liu Z, Li X

Geographical coverage: Italy, Spain, France, Portugal, Brazil, India, Israel, Germany, China, and the Netherlands

Sector: Biomedical

Sub-sector: Treatment

Equity focus: None

Study population: Patients who have received implantation of intraocular lenses (IOLs) or multifocal IOLs (MIOLs) after undergoing cataract surgery.

Review type: Effectiveness review

Quantitative synthesis method: Systematic review and meta-analysis

Qualitative synthesis method: Not applicable

Background: Lens extraction combined with intraocular lens (IOL) implantation improves visual quality post-cataract surgery. Monofocal IOLs offer excellent distance visual acuity but require spectacles for near and intermediate vision. Multifocal IOLs (MIOLs) improve intermediate and near visual acuity, but visual quality between separate foci is unsatisfactory, and they can cause disturbing photic phenomena like halos and glare. Extended depth of focus (EDOF) IOLs, such as the widely used TECNIS Symfony, were introduced to address these issues. These IOLs, which have an aspheric anterior surface and a continuum of foci, are expected to reduce photic phenomena and bridge the gap between MIOLs and monofocal IOLs. However, the specific clinical effect of EDOF IOLs is still unclear.

Objectives: To compare the outcomes of implantation of trifocal intraocular lenses (TIOLs) and extended depth of focus (EDOF) intraocular lenses (IOLs).

Main findings:

Overall findings of the review showed that EDOF IOLs and TIOLs provide comparable distance vision. However, EDOF IOLs provide better intermediate vision and worse near vision than TIOLs. The advantages of EDOF IOLs over TIOLs in terms of CS, aberrations, and visual disturbance are not significant. Patients are satisfied with both types of IOLs.

A total of 13 studies (four RCTs and nine NRCSs) were included in the analysis. All studies were published between 2017 and 2020. 1,221 eyes were included in the analysis. The TECNIS Symfony ZXR00 IOL was implanted in the eyes included in the EDOF group, whereas AcrySof IQ PanOptix, FineVision Micro F, FineVision Pod F, and AT LISA tri 839MP IOLs were implanted in the eyes included in the trifocal group. The follow-up duration of the studies ranged from one to 29 months.

Authors found the included RCTs had low or unclear risk of bias, generally. For the NRCs, seven studies were high-quality, whereas two were of moderate quality.

TIOLs and EDOF IOLs provided comparable binocular UDVA (MD -0.01, 95% CI: -0.04, 0.03, logMAR). However, EDOF IOLs provided better UIVA (MD: -0.08, 95% CI: -0.14, -0.01, logMAR) and worse UNVA (MD: 0.10, 95% CI: 0.06, 0.14, logMAR) than TIOLs. Fewer patients achieved spectacle independence after implantation of EDOF IOLs (RR: 0.74, 95% CI: 0.63, 0.87) than after implantation of TIOLs, especially for near vision (RR 0.82, 95% CI: 0.68, 0.99). There was no statistically significant difference in contrast sensitivity (CS) under photopic or mesopic conditions with both IOLs. Patient satisfaction after implantation of both IOLs was high.

Authors found the presence of publication bias in spectacle independence for distance vision, visual acuity at a defocus level of +1D, and CS (1.5cpd, mesopic). The trim-and-fill method was used to adjust these indicators, after which the results remained unchanged.

Authors noted that more clinical studies on the other EDOF IOLs are needed.

Methodology:

he study selected randomised controlled trials (RCTs) and nonrandomised controlled studies (NRCSs) that compared the implantation of EDOF IOLs and TIOLs post-cataract surgery. Ongoing studies and those on binocular blended implantation were excluded. Primary outcomes were monocular and binocular uncorrected visual acuity at different distances and defocus curves, with defocus levels ranging from +1.00 to -4.00 dioptres in 0.50 D steps. Secondary outcomes included corrected visual acuity at different distances, refraction parameters, spectacle independence, contrast sensitivity, aberrations, quality of vision, patient satisfaction, and complications and adverse events.

The authors conducted a comprehensive search on PubMed, Cochrane Library, EMBASE, and ClinicalTrial.gov for relevant controlled studies published from January 2000 to March 2020. They used specific terms related to “extended depth of focus” and “intraocular lenses” without any language restrictions. They also manually searched the reference lists of key articles and relevant systematic reviews to find other potential studies. The search was independently carried out by two reviewers, with a third reviewer consulted in case of disagreements. The quality of RCTs was assessed using the Cochrane Collaboration risk-of-bias tool. The Newcastle-Ottawa Scale (NOS) was used to assess the risk of bias of NRCSs.

Two reviewers independently extracted data from the included studies using a standard form. Discrepancies between the decisions of the two reviewers were resolved by consensus; a third reviewer was consulted when necessary. The characteristics of each study were extracted and their outcomes detailed. For continuous variables, including visual acuity, defocus curves, refraction and CS, the mean values and standard deviations (SD) were extracted. For dichotomous variables, the number of events, such as spectacle independence, in each treatment group was extracted. For data that could not be merged, such as quality of vision and patient satisfaction, results were summarised and described. The authors of the studies were contacted for additional information by email when necessary.

Data was analysed using Review Manager 5.3 and Stata/SE 14.0 software. Heterogeneity was assessed using the Q test and I² statistic, with I² > 50% indicating substantial heterogeneity. Depending on the I² value, either a random-effects or fixed-effects model was used. Mean deviation (MD) with a 95% confidence interval (CI) was calculated for continuous variables, except contrast sensitivity (CS), and risk ratio (RR) or risk deviation (RD) with 95% CI for categorical variables. A p-value <0.05 was considered statistically significant. Publication bias was checked using funnel plots and Egger’s test, with trim-and-fill analysis conducted for any noted funnel plot asymmetry. Influence analysis was performed to verify result stability. For studies with two different TIOL implantation groups, mean values and standard deviations were combined for meta-analysis using specific formulas.

Applicability/external validity: In their discussion, the authors referenced a prior meta-analysis that yielded similar results. They pointed out that to minimize bias from the type of IOL, bifocal IOLs were excluded from the analysis. However, due to the potential limitation of the number of RCTs, NRCSs were also included. Moreover, only Symfony IOLs were included as representatives of EDOF IOLs, as no RCTs or NRCSs comparing TIOLs and other types of EDOF IOLs were found at the time of their database search. Consequently, the validity of the reported results for these specific treatment types may be somewhat compromised.

Geographic focus: Review included studies from a wide range of countries including high and low- and middle-income countries.

Summary of quality assessment:

The approaches used to identify, include, and critically appraise studies were generally highly rigorous, with at least two authors undertaking all key tasks and a search that was inclusive in terms of language. However, no attempt was made to include unpublished material and it is unclear whether a time limit for the search was implemented. The approach to the analysis of the data was generally rigorous; however, given the inclusion of RCTs, it is unclear if and how unit of analysis errors were accounted for in the analysis. For these reasons, there is medium confidence in the findings of this review.