Comparison of outcomes with multifocal intraocular lenses: a meta-analysis

Methodological quality of the review: Low confidence

Author: Cochener B, Lafuma A, Khoshnood B, Courouve L, Berdeaux G.

Region: Details not provided

Sector: Multifocal intraocular lenses

Sub-sector: Clinical outcomes

Equity focus: None specified

Review type: Effectiveness review

Quantitative synthesis method: Meta-analysis

Qualitative synthesis methods: Not applicable

Background

Traditional intraocular lenses (IOLs) are monofocal, and after implantation most patients need spectacles, at least for near vision. Multifocal IOLs are intended to free patients from spectacles after presbyopia or cataract surgery by applying the principle of simultaneous vision. Early multifocal IOLs were associated with loss of clarity and poor accommodation, reduced contrast sensitivity, and complaints of halos and glare. Improvements in intraocular lens technology have enabled cataract patients to be implanted with multifocal IOLs to provide better visual acuity at various distances and a degree of spectacle independence. Today, multifocal IOLs produce functional near and distance vision and acceptable levels of patient satisfaction in everyday practice. However, reviews on the clinical consequences of multifocal implantations are rare.

Research objectives

To conduct a meta-analysis of published comparative clinical trials in which at least one patient group was implanted with multifocal implants bilaterally.

Main findings

In total the authors included 20 studies, 16 were prospective and four were retrospective. Eight of the prospective studies were randomized. 11 papers described patient cohorts receiving monofocal intraocular lenses (IOLs) and 35 multifocal IOLs (19 diffractive, including 12 ReSTOR®, 14 refractive, and two accommodative).

Multifocal and monofocal uncorrected distance visual acuity was 0.165 (0.090–0.240) and 0.093 (0.088–0.098), respectively. Compared with monofocal IOLs, multifocal IOLs produced better uncorrected near visual acuity (0.470 [0.322–0.618] versus 0.141 [0.131–0.152]; P , 0.0001), resulting in higher spectacle independence (incidence rate ratio [IRR] 3.62 [2.90–4.52]; P , 0.0001). Compared with refractive multifocal IOLs, diffractive multifocal IOLs produced a similar uncorrected distance visual acuity (0.105 [0.098–0.111] versus 0.085 [0.029–0.140]; P > 0.78, not significant) and better uncorrected near visual acuity (0.217 [0.118–0.317] versus 0.082 [0.067–0.098]; P , 0.0001) resulting in higher spectacle independence (IRR 1.75 [1.24–2.48]; P , 0.001). Compared with other multifocal IOLs, ReSTOR produced a better uncorrected distance visual acuity (0.067 [0.059–0.076] versus 0.093 [0.088–0.098]; P , 0.0001) and better uncorrected near visual acuity (0.064 [0.046–0.082] versus 0.141 [0.131–0.152]; P , 0.006), resulting in higher spectacle independence (IRR 2.06 [1.26–1.36]; P , 0.004). Halo incidence rates with different types of multifocal implants did not differ significantly.

Based on these findings, the authors concluded that ‘multifocal IOLs offer patients better near uncorrected visual acuity than do monofocal implants. Also, ReSTOR provided significantly better visual acuity than other multifocal IOLs.’ They also reported that spectacle independence was achieved more frequently with multifocal implants than monofocal IOLs.

Methodology

Inclusion criteria were publications in French or English, bilateral implementation of the same IOL, use of Tecnis, Scrisisa, Rezoom, Diffrectiva, Rayner, or ReSTOR implants and publication from 2000 onwards.

The authors conducted a search of Medline. Search included words related to multifocal IOLs such as Acrilisa, together with keywords focusing on comparative clinical trials i.e. ‘cataract surgery’. Abstracts were scrutinized and full articles ordered and analyzed in depth if they reported comparative studies in adult patients. All the available data from the selected articles were extracted and tabulated with respect to each study’s identity, its design, IOL names and type, reasons for IOL implantation, number is patients at baseline and at final follow-up, average follow-up duration, final overall patient satisfaction, spectacle dependency, uncorrected distance visual acuity, uncorrected intermediate visual acuity, uncorrected near visual acuity, and the number of patients reporting halos. Clinical outcomes included uncorrected near visual acuity, uncorrected distance visual acuity, visual acuity, spectacle independence, and halos.

The authors conducted a random effects meta-analysis to compared outcomes for the different IOL types.

Applicability/external validity

The authors did not discuss the applicability/ external validity of findings.

Geographic focus

The authors did not focus on specific income settings. However, they did not report the geographical location of included studies and did not describe how applicable the results may be to low- and middle-income settings.

Quality assessment

Low confidence was attributed in the conclusions about the effects of this study as major limitations were identified. The search for literature was not comprehensive enough that we can be confident that relevant studies were not omitted in the review. For instance, publications from 2000 onwards were included in the review. It is not possible to determine whether risk of bias was avoided in the methods used select studies and extract data of included studies as authors do not mention independent screening of full text; particularly no information was provided whether the screening was done by at least two reviewers. The authors also did not report assessing quality and risk of bias of studies included in the meta-analysis, therefore it is not possible to determine if the meta-analysis consisted of studies with low or high risk of bias which depending on the risk, may impact on the validity of the findings.

Although an important number of relevant studies were included in the review, the authors noted that most did not randomize treatments, which could be considered as poor evidence reporting. Therefore, authors included prospective and retrospective studies, which were not similar enough that it made sense to combine them. It may have been more appropriate to conduct a narrative synthesis of studies rather than a meta-analysis.