This well-conducted systematic review compared accommodating intraocular lens and monofocal intraocular lens in restoring accommodation in cataract surgery. The authors concluded that there was no clear evidence of near acuity improvement with accommodating intraocular lens. Given the poor quality and significant heterogeneity between the included trials, this conclusion was appropriate.

To compare accommodating intraocular lens with monofocal intraocular lens in restoring accommodation in cataract surgery.

MEDLINE (1950 to 2008), the Cochrane Library and ClinicalTrials.gov were searched to October 2008; search terms were reported. Reference lists of relevant articles were also searched for additional potentially relevant studies. No language or publication restrictions were applied.

Randomised controlled trials (RCTs) that compared accommodating intraocular lens with standard monofocal intraocular lens in adult (over 19 years) cataract surgery patients were eligible for inclusion.

The primary outcome of interest was distance-corrected near visual acuity. Secondary outcomes of interest were pilocarpine-induced anterior chamber displacements, reading speed, glare, contrast sensitivity, spectacle independence, and adverse effects.

Trial locations included France, Italy, Austria, Germany, Japan and the UK. The mean patient age ranged from 62 to 76 years; the mean proportion of male patients ranged from 34.5 to 53.3% (where reported). Most of the included trials used the 1CU accommodating intraocular lens; there were various brands of monofocal intraocular lens.

Two reviewers independently selected the studies, with any disagreements resolved by consensus.

The quality of the included trials was assessed using a modified version of the van Tulder validity assessment tool. Trials scoring 6 or more, out of a maximum possible score of 10, were considered to be of adequate quality.

The authors did not state how many authors performed the validity assessment.

Mean differences in outcomes between accommodating intraocular lens and monofocal intraocular lens were extracted by two reviewers independently, disagreements were resolved by discussion. Where data were missing from included trials, the authors of the trials were contacted. When authors did not provide the missing data, values were estimated using formulae described in the Cochrane handbook. When values could not be obtained or estimated, trials were excluded from the meta-analysis.

A random-effects model was used to pool standardised mean differences (SMDs) with 95% confidence intervals (CIs) for distance-corrected near visual acuity outcomes, and weighted mean differences (WMDs), with 95% confidence intervals, for pilocarpine-induced anterior chamber displacement outcomes. For other secondary outcomes where few trials consistently reported quantitative results, quantitative results were pooled where possible; otherwise results were described narratively.

Heterogeneity was assessed using I². When there was substantial heterogeneity, the characteristics of trials with outlying results were assessed in an attempt to determine whether an explanation could be identified. Sensitivity analyses were performed excluding trials responsible for the heterogeneity. Sensitivity analyses were also performed based on the results of the validity assessment, length of follow-up, type of intraocular lens studied, trial location, monocular intraocular lens versus binocular intraocular lens implantation, fellow-eye versus interpatient-eye comparisons, and measurement scales (Jaeger versus logMAR).

Publication bias was assessed using a funnel plot.

Twelve RCTs (727 eyes) were included in the review. Sample sizes ranged from 22 to 180 eyes. Quality assessment scores ranged from 4 to 9 out of a possible maximum score of 10 points. Five trials scored 6 or more out of 10 and were considered to be of adequate quality. Most trials did not report the method of allocation concealment, methods of blinding, or an acceptable rate of drop-outs. None of the trials an intention-to-treat analysis. The duration of follow-up ranged from four weeks to two years; six RCTs had follow-up of at least one year.

Accommodating intraocular lens significantly improved distance-corrected near visual acuity compared with monofocal intraocular lens (SMD -1.36, 95% CI -2.22 to -0.49; 10 RCTs). However, there was significant statistical heterogeneity (I²=94%), which could not be explained by any population or methodology characteristic. When the six homogeneous RCTs were pooled, there was no significant difference in distance-corrected near visual acuity between accommodating intraocular lens and monofocal intraocular lens.

Accommodating intraocular lens were associated with significantly greater anterior lens shift than monofocal intraocular lens (WMD -0.36, 95% CI -0.47 to -0.24; four RCTs). There was also significant statistical heterogeneity (I²=58%), which could not be explained by any population or methodology characteristic.

There were no statistically significant differences in glare (two RCTs) or contrast sensitivity (two RCTs) between accommodating intraocular lens and monofocal intraocular lens. Two trials reported better reading speed in the accommodating intraocular lens group. One trial reported better spectacle independence in the accommodating intraocular lens group.

Regarding adverse events, five RCTs reported rates of posterior capsule opacification, with four of the RCTs reporting increased rates in the accommodating intraocular lens group several months after surgery. One RCT reported a patient suffering anterior chamber haemorrhage. One RCT reported a patient suffering posterior capsule shrinkage.

The funnel plot did not indicate that publication bias was present.

There was no clear evidence of near acuity improvement with accommodating intraocular lens, despite statistically significant pilocarpine-induced anterior lens displacement.

The review question was clearly defined in terms of study design, participants, interventions and outcomes of interest. The authors searched three databases for relevant trial, including two controlled trial registers, reducing the potential for publication bias. Publication bias was assessed and was not found to be present. No language restrictions were applied, which reduced the potential for language bias. Study selection and data extraction procedures were undertaken independently by two reviewers, reducing the potential for bias and errors.

Validity was assessed according to published criteria and the results were fully reported and used in sensitivity analyses. The majority of the included trials were poor quality. The trials reported the number of eyes, rather than the number of participants included, so some patients may have been included twice, which is a potential source of bias. Appropriate methods were used to pool the results and to investigate statistical heterogeneity. There was significant heterogeneity between trials, which could not be explained by any population or methodology characteristic.

This was a well-conducted systematic review and the authors’ conclusion was appropriate.

Practice: The authors stated that patients should be fully informed about the risks and benefits of accommodating intraocular lens before choosing this relatively new type of intraocular lens.

Research: The authors stated that double-blinded RCTs of longer duration are required, using standardized methods for measuring visual acuity and accommodating functions in pseudophakic patients. Future RCTs should assess adverse effects, such as posterior capsule opacification, and cost effectiveness.

Not stated.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.