Three-Dimensional Heads-Up vs. Standard Operating Microscope for Cataract Surgery: A Systematic Review and Meta-Analysis

Author: Ripa M, Kopsacheilis N, Kanellopoulou K, Nomikarios M, Motta L.

Geographical coverage: India, the United States, Europe and East Asia

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: Over the past two decades, three-dimensional (3D) heads‑up visualisation systems (HUVS) have become increasingly popular in ophthalmic surgery. These platforms enable surgeons to operate while viewing a high‑definition 3D monitor rather than conventional microscope eyepieces. They enhance stereopsis, ergonomics and magnification, and allow the entire surgical team to share the same view, which also makes them valuable for training. Despite growing interest, concerns persist regarding longer operating times, a steep learning curve and higher perceived workload. Most existing literature centres on vitreoretinal procedures, so evidence specific to cataract surgery remains limited. In addition, studies use inconsistent measures of visual comfort, posture, manoeuvrability and other subjective endpoints. As adoption of HUVS grows worldwide, a critical appraisal of their advantages and limitations in cataract surgery is warranted.

Objective: To evaluate the impact of 3D HUVS on cataract surgery by comparing mean operating time, postoperative best‑corrected visual acuity (BCVA) and the incidence of intra‑operative complications with those achieved using a standard operating microscope (SOM). Secondary aims included assessing visual comfort, surgeon posture and other ergonomics‑related variables.

Main findings: The review included 11 studies (8842 eyes) published between 2019 and 2022. Among these, 3 were randomised controlled trials (RCTs), 2 were non-randomised studies (NRSs), and 6 were comparative retrospective studies.

Pooled data from nine studies involving 5,505 eyes revealed no statistically significant difference in surgical time between the two systems (weighted mean difference, WMD = 0.17 minutes, 95% CI: −0.43 to 0.76, p = 0.58). However, substantial heterogeneity was observed (I² = 95.11%), which was primarily driven by two outlier studies. When these outliers were excluded, heterogeneity dropped significantly (I² = 11%), and the difference in surgical time became negligible (WMD = 0.03 minutes, 95% CI: -0.09 to 0.15, p = 0.59), suggesting that surgical duration is comparable between the two systems after accounting for the learning curve.

Postoperative best-corrected visual acuity (BCVA) was analysed across five studies comprising 1,021 eyes. The results demonstrated no clinically meaningful difference between HUVS and the standard operating microscope [SOM] (WMD = −0.01 LogMAR, 95% CI: −0.01 to 0.02, p = 0.36). Similarly, the incidence of intraoperative complications, assessed across nine studies with 8,609 eyes, showed no significant difference between the two systems (risk ratio, RR = 1.00, 95% CI: 1.00 to 1.01, p = 0.55). Complications such as posterior capsule rupture, iris trauma, and nucleus drop occurred at comparable rates in both groups.

Methodology:  Searches of PubMed, Embase and Scopus were performed from database inception to 26 June 2022 for prospective or retrospective studies comparing 3D HUVS with SOM in cataract surgery. Reference lists of included papers were screened for additional publications. Two reviewers independently screened articles, extracted data, and assessed risk of bias; disagreements were resolved by discussion. Risk‑of‑bias tools included the Cochrane tool for RCTs, MINORS for non‑randomised studies and the Newcastle–Ottawa Scale for observational cohorts. Random‑effects meta‑analysis was undertaken; heterogeneity was examined with the χ² test and I² statistic. Sensitivity analyses used a leave‑one‑out approach, and publication bias was explored with funnel plots and Egger’s test.

Two reviewers independently screened the articles, extracted the relevant data, assessed the risk of bias, and quality of evidence for each outcome. The risk of bias was assessed using the Cochrane Collaboration’s Tool for randomised studies, the methodological index for non-randomised studies (MINORS) for non-randomised studies and the Newcastle-Ottawa Scale for observational studies, and the quality of evidence was evaluated using the (Grading of Recommendations Assessment, Development, and Evaluation) GRADE framework. Discrepancies between the reviewers were resolved through discussion.

The findings were synthesised using a random-effects meta-analysis. Heterogeneity was assessed using the Cochrane Q-test and I2 statistics. Sensitivity analysis was performed using the leave-one-out method, and the publication bias was assessed using a funnel plot and Egger’s test.

Applicability/external validity: Variation in study design, sample size and surgical technique limits generalisability. While current evidence suggests that 3D HUVS yields comparable operating times, visual outcomes and safety profiles to SOM, larger multicentre trials are needed to confirm effectiveness across diverse surgical settings.

Geographic focus: No geographical limits were imposed; the included studies originated mainly from India, the United States, Europe and East Asia.

Summary of quality assessment: Overall confidence in the review’s conclusions is medium. The search strategy was comprehensive, and risk‑of‑bias assessment employed recognised tools, but segregation of results by study quality and a list of excluded studies were not provided.