Enhanced Monofocal Versus Conventional Monofocal Intraocular Lens in Cataract Surgery: A Meta-analysis

Author: Wan KH, Au ACK, Kua WN, Ng ALK, Cheng GPM, Lam NM, Chow VWS.

Geographical coverage: Spain, Italy, Portugal, Turkey, United Kingdom, Korea and India

Sector: Cataract surgery

Sub-sector: Treatment comparison

Equity focus: Not reported

Study population: Patients with cataract

Review type: Effectiveness review

Quantitative synthesis method: Meta-analysis

Qualitative synthesis method: Not applicable

Background:

Cataract surgery is increasingly performed at younger ages and is now considered part of the broader spectrum of refractive procedures. With rising demand for spectacle independence, new intraocular lens (IOL) designs have been developed. Multifocal and extended depth of focus (EDOF) IOLs offer improved unaided vision at various distances but are often associated with photic phenomena such as halos and glare, as well as the need for neuroadaptation. In response, enhanced monofocal IOLs such as the Tecnis Eyhance were introduced. These lenses feature a modified aspheric anterior surface that increases optical power from the periphery to the centre, enhancing intermediate vision while maintaining good distance vision and reducing the risk of optical disturbances. These designs aim to meet the increasing visual demands of modern routine activities such as using digital devices or driving.

Objectives:

To assess the benefits and potential harms of all models of enhanced monofocal IOLs in patients undergoing phacoemulsification.

Main findings:

This systematic review and meta-analysis included 12 studies: 3 randomised controlled trials (RCTs) and 9 comparative studies (4 prospective, 5 retrospective). The studies were conducted in Europe (n=9) and Asia (n=3). Overall, RCTs were categorised as low risk of bias, and non-randomised studies as moderate risk of bias.

The analysis focused on various visual and patient-reported outcomes following cataract surgery. The enhanced monofocal IOL showed statistically significant improvements in uncorrected intermediate visual acuity (UIVA), both monocular (mean difference [MD]: –0.11 logMAR; 95% CI: –0.12 to –0.09) and binocular (MD: –0.17 logMAR; 95% CI: –0.23 to –0.11), compared with conventional monofocal IOLs. Binocular uncorrected near visual acuity (UNVA) was also better in the enhanced group (MD: –0.17 logMAR; 95% CI: –0.29 to –0.04). However, there were no significant differences in uncorrected distance visual acuity (UDVA) or in most corrected visual acuity outcomes across distances.

Enhanced monofocal IOLs significantly increased spectacle independence at intermediate distances (odds ratio: 12.9; 95% CI: 6.2 to 27.0). Patient satisfaction scores were generally similar between groups, with some evidence suggesting better satisfaction for intermediate vision tasks in the enhanced monofocal IOL group. Specific activities such as reading price tags, using a computer, or reading newspapers were performed with greater ease among Eyhance users.

Optical quality outcomes, including objective scatter index (OSI) and modulation transfer function (MTF), were comparable between groups. The Strehl ratio was slightly lower in the enhanced monofocal IOL group (MD: –0.02; 95% CI: –0.05 to –0.0001). Importantly, there were no significant differences in the incidence of halos or glare, indicating that the enhanced design does not increase photic disturbances. Four studies assessed contrast sensitivity under various lighting conditions and at different spatial frequencies. All found comparable results between enhanced and conventional monofocal IOLs. Postoperative complications were rare and did not differ between groups. The most commonly reported complication was cystoid macular oedema, with only one study noting a slightly higher rate in the Eyhance group for first-eye surgery (7.4% vs 5.4%), though this was not statistically significant.

Methodology:

The searches were conducted in PubMed, Embase, and the Cochrane Library to identify studies comparing enhanced monofocal IOLs with conventional monofocal IOLs in participants undergoing cataract surgery or refractive lens exchange in one or both eyes. No language limits were applied. Reference lists of potentially relevant studies were thoroughly scanned to identify additional publications.

Relevant data were extracted, and the methodological quality of the included studies was assessed using the Cochrane risk-of-bias tool (RoB 2) for RCTs and ROBINS-I for non-randomised studies. Findings were synthesised using either a fixed-effect or a random-effects model meta-analysis, depending on heterogeneity. Sensitivity analyses were performed using a random-effects model for all analyses. Subgroup analysis was performed according to the IOL model used in the conventional monofocal IOL group. Heterogeneity was assessed using I² and Chi-squared tests, and publication bias using Egger’s test and trim-and-fill analysis.

Applicability/external validity:

The review highlighted that it had a narrow focus, and that its findings apply only to the Eyhance IOL. In addition, it noted that the evidence was drawn exclusively from studies conducted in Europe and Asia, which may not fully reflect outcomes in other healthcare settings. Furthermore, the evidence base consisted of only three randomised controlled trials and nine non-randomised studies. The review underscored the need for more RCTs to confirm the benefits and potential trade-offs between enhanced monofocal IOLs and conventional monofocal IOLs.

Geographic focus:

The review did not apply any geographical limits. Included studies were conducted in Europe (Spain, Italy, Portugal, Turkey, United Kingdom) and Asia (Korea, India).

Summary of quality assessment:

Overall, confidence in the review’s conclusions about the effects is low. The review employed a comprehensive search strategy with clearly defined inclusion and exclusion criteria. The risk of bias in the included studies was assessed using established tools. Study characteristics were thoroughly documented. Findings were synthesised using either a fixed-effect or a random-effects model meta-analysis. Sensitivity analyses were performed using a random-effects model for all analyses. Subgroup analyses were performed according to the IOL model used in the conventional monofocal IOL group. Heterogeneity was assessed using I² and Chi-squared tests, and publication bias using Egger’s test and trim-and-fill analysis. However, the review did not include a list of excluded studies, nor did it present findings stratified by risk of bias. Moreover, it did not specify how many reviewers independently conducted study screening and data extraction.