Real-world visual outcomes of cataract surgery based on population-based studies: a systematic review

Author: Han X, Zhang J, Liu Z, Tan X, Jin G, He M, Luo L, Liu Y.

Geographical coverage: Asia, Europe, Africa, North America, Oceania, and Latin America & the Caribbean

Sector: Cataract surgery

Sub-sector: Visual outcomes

Equity focus: Not reported

Study population: Patients with cataract

Review type: Effectiveness review

Quantitative synthesis method: Narrative synthesis

Qualitative synthesis method: Not applicable

Background:

Cataract surgery is the most commonly performed elective operation worldwide, with more than 20 million procedures carried out each year. Although highly cost-effective, cataract remains the leading cause of global blindness. As surgical volumes rise to tackle the backlog of cataract-related vision loss, it is increasingly important to monitor the quality of outcomes. Advances such as micro-incision techniques and improved intra-ocular lenses (IOLs) have enhanced the potential benefits of surgery, yet marked disparities in outcome persist both between and within countries, reflecting differences in health-care resources and clinical practice. Post-operative visual acuity (VA) is a simple, widely accepted indicator of surgical quality and subsequent care. Ensuring consistently high outcomes is critical to maximising patient benefit, reducing inequality and achieving universal eye-health goals.

Objective:

To summarise post-operative visual status reported in representative population-based studies from high-income countries (HICs) and low- and middle-income countries (LMICs), and to identify the main causes of visual impairment (VI) after cataract surgery.

Main findings:

The review included 35 studies: 31 cross-sectional (26 LMICs; 5 HICs) and four cohort studies (China × 2, Australia × 1, Sweden × 1).

VA varied widely. In HICs, more than 70 % of patients achieved presenting VA (PVA) ≥ 20/60 (0.32). In LMICs this proportion ranged from 29.9 % to 80.5 %, with most studies reporting < 70 %. China and India contributed most LMIC data, their post-operative PVA ≥ 20/60 spanning 44.5 %–73.5 % and 37 %–74.6 %, respectively.

The leading causes of postoperative visual impairment (VI) differed between regions. In HICs,  uncorrected refractive error and ocular co-morbidity (e.g. age-related macular degeneration, glaucoma) were the primary contributors. In LMICs, VI was often due to a combination of RE, ocular comorbidities, and surgical complications, including posterior capsule opacification (PCO). Strikingly, in Nigeria, uncorrected aphakia (absence of an intraocular lens) was the predominant cause of poor outcomes, underscoring gaps in surgical quality and access to advanced techniques like phacoemulsification. Overall, while global cataract-surgery rates have risen, substantial inequalities in surgical quality persist, particularly in LMICs.

Methodology:

PubMed, Embase and Google Scholar were searched (1 January 2006 – 15 November 2021) for population-based studies reporting vision outcomes after cataract surgery. Only full-text, English-language originals were eligible. Reference lists were hand-searched. Two reviewers independently screened records and appraised quality using the Newcastle–Ottawa Scale; disagreements were resolved through discussion or third-reviewer arbitration. Findings were synthesised narratively.

Applicability / external validity:

Generalisability is limited by the dominance of cross-sectional studies from a handful of LMICs (notably China and India) and the scarcity of long-term cohort data. Heterogeneity in surgical technique, outcome definitions and follow-up protocols further constrains applicability. Structured quality-improvement programmes are needed to enhance outcomes and reduce inequity.

Geographic focus:

Studies were conducted across Asia, Europe, Africa, North America, Oceania, and Latin America & the Caribbean; no geographical limits were applied.

Summary of quality assessment:

Confidence in the review conclusion is low. Searches were comprehensive, inclusion/exclusion criteria explicit, and dual-reviewer processes used for screening and quality appraisal. Study characteristics were well documented; however, restriction to English-language reports, absence of an excluded-studies list, and unspecified reviewer numbers for data extraction reduce overall certainty.