Phaco-Chop versus Divide-and-Conquer in Patients Who Underwent Cataract Surgery: A Systematic Review and Meta-Analysis

Author: Guedes J, Pereira SF, Amaral DC, Hespanhol LC, Faneli AC, Oliveira RDC, Mora-Paez DJ, Fontes BM.

Geographical coverage: India, Italy, South Korea, Mexico, Denmark, the United Kingdom and Hungary

Sector: Cataract surgery

Sub-sector: Efficacy and safety

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 is the leading cause of global blindness, characterised by lens opacity, refractive change and increasing light scatter that progressively impair vision. Prevalence rises steeply with age and is expected to affect nearly 40 million people by 2025. Phacoemulsification, introduced in 1967, remains the surgical gold standard owing to its efficiency and safety. Two of its most widely used nucleus-fragmentation techniques are divide-and-conquer (developed in 1985) and phaco-chop (introduced in 1993). Divide-and-conquer uses deep sculpting grooves to split the nucleus, whereas phaco-chop relies on direct mechanical chopping. Both aim to minimise ultrasound energy and preserve corneal endothelial cells, yet debate continues as to which offers superior clinical outcomes.

Objective:

To compare the efficacy and safety of the phaco-chop technique with the divide-and-conquer technique.

Main findings: The review included 8 studies, comprising 837 participants. Six studies were prospective randomised controlled trials (RCTs) and 3 were observational studies. One study combined both randomised controlled trial (RCT) and observational study components. The included studies were conducted in India (n=1), Italy (n=1), South Korea (n=1), Mexico (n=1), Denmark (n=1), Hungary (n=1), and the United Kingdom (n=1). The geographical location of one study was not reported. The methodological quality of the included studies was assessed as having “some concerns” regarding bias, primarily due to deviations from intended interventions. Among the observational studies evaluated using the ROBINS-I tool, three were classified as having a moderate risk of bias, stemming from confounding factors and participant selection issues.

The results demonstrated that the phaco-chop technique was associated with significant advantages, including a lower reduction in endothelial cell count (mean difference [MD]: –221.67 cells/mm², 95% confidence interval [CI]: -401.68 to -41.66), reduced cumulated dissipated energy (MD: –8.68 units, 95% CI: -12.76 to -4.60), shorter ultrasound time (MD: –51.16 seconds, 95% CI: -99.54 to -2.79), and decreased phacoemulsification time (MD: –55.09 seconds, 95% CI: -99.29 to -12.90) compared to the divide-and-conquer method. However, no significant difference was observed in total surgery time between the two techniques (MD: -3.86, 95% CI: -9.55 to 1.83).

Subgroup and sensitivity analyses confirmed the robustness of these findings, though high heterogeneity was noted in some outcomes, such as phacoemulsification time (I²=100%). The phaco-chop technique’s benefits were attributed to its lower energy requirements and reduced mechanical stress on corneal endothelial cells. The authors concluded that phaco-chop is a safer and more efficient alternative but called for further long-term studies to validate these findings across diverse clinical settings.

Methodology:  The searches were conducted in PubMed, Scopus, and Cochrane Central Register of Controlled Trials from inception to October 2023 to identify RCTs and observational studies comparing the phaco-chop technique with the divide-and-conquer technique in patients with cataract surgery. No language limits were applied, and the studies were included if they reported at least one of the following outcomes: change in endothelial cell count (ECC), ultrasound time (UST), cumulated dissipated energy (CDE), surgery time and phacoemulsification time. The reference lists of included studies were also scanned to identify additional relevant publications.

Two reviewers independently screened the articles, extracted the relevant data and critically appraised the quality of the included studies using the Cochrane’s risk of bias tools (risk of bias version 2 [ROB-2] for RCTs and Risk of Bias in Non-randomised Studies of Interventions tool [ROBINS- I] for non-randomised studies). Disagreements between the reviewers were resolved through discussion. The findings were synthesised using a random-effects model meta-analysis. Heterogeneity was assessed using the Cochrane Q-test and I² statistics, and publication bias using a funnel plot. Subgroup analysis was performed by study design to identify if heterogeneity of results would arise from different design settings. Sensitivity analysis was conducted to explore the influence of s single study on the overall results.

Applicability / external validity:

Generalisability is limited by the inclusion of non-randomised studies, variable reporting of cataract density, short follow-up periods and procedures performed by different surgeons. These factors, together with moderate heterogeneity, may constrain applicability to broader clinical practice. Standardised protocols and longer follow-up are required to strengthen external validity.

Geographic focus:

Studies were conducted in India, Italy, South Korea, Mexico, Denmark, the United Kingdom and Hungary; one study did not specify its location. No geographical limits were applied.

Summary of quality assessment:

Overall confidence in the conclusions is high. Searches were comprehensive; inclusion criteria were explicit; dual-reviewer processes adhered to recognised standards; study characteristics and risk-of-bias assessments were detailed; and heterogeneity was addressed appropriately. The absence of an excluded-studies list is a minor shortcoming.