Association between cataract surgery and age-related macular degeneration: a systematic review and meta-analysis

Author: Yang L, Li H, Zhao X, Pan Y.

Geographical coverage: United States, Australia, Germany, Israel, Denmark, the Netherlands, Switzerland, Taiwan, and Austria.

Sector: Cataract surgery

Sub-sector: Age-related macular degeneration

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 and age-related macular degeneration (AMD) are leading causes of vision loss in elder people. With increasing life expectancy, cataract surgeries are becoming more frequent worldwide. Although the surgery enhances visual function, the AMD is a common comorbidity in these patients, which raises concerns about possible adverse effects. The epidemiological studies examining the association between cataract surgery and AMD have shown inconsistent results, and did not account for key influencing factors such as study design, follow-up duration, sample sources, and adjustment for confounders. Understanding whether cataract surgery influences AMD onset or progression is crucial, especially regarding AMD subtypes and longer-term outcomes.

Objectives: To evaluate the association between cataract surgery and the development and progression of AMD

Main findings: The review included 15 studies (12 population-based cohort studies, 2 randomised controlled trials [RCTs], and 1 case-control study) published between 1998 and 2017. The included studies were geographically diverse, originating from the United States, Australia, Germany, Israel, Denmark, the Netherlands, Switzerland, Taiwan, and Austria. The follow-up durations in the included studies ranged from 6 months to 20 years. Seven studies (7 of 15) had a high risk of bias in at least one domain.

Cataract surgery was significantly associated with an increased risk of late AMD (pooled odds ration [OR]: 1.80, 95% confidence interval [CI]: 1.26 to 2.56; p = 0.001), particularly geographic atrophy (OR: 3.20, 95% CI: 1.90 to 5.39; p ≤ 0.001). No statistically significant association was found between cataract surgery and early AMD (OR: 1.15, 95% CI: 0.96 to 1.37; p = 0.139). AMD progression was also significantly associated with cataract surgery (OR: 1.40, 95% CI: 1.10 to1.80; p = 0.014). Subgroup analyses showed that associations were stronger for follow-up durations greater than 5 years and varied by AMD subtype.

Methodology: The searches were conducted in PubMed and Embase in August 2020 to identify RCTs, cohort, and case-control studies evaluating the effect of cataract surgery on the development or progression of AMD. Additional searches of all relevant trials and review articles were conducted to find further eligible studies. The review did not apply any language restrictions in the search of trials.

Two reviewers independently extracted the relevant data. Discrepancies were resolved by consensus. The methodological quality of observational studies was assessed using the Non-randomized Studies of Interventions (ROBINS-I) tool while the Cochrane Collaboration tool was used to assess the risk of bias for randomised trials. The findings were synthesised using fixed and random-effect model meta-analysis. Stratified analyses were performed to investigate potential sources of between-study heterogeneity. Sensitivity analyses were performed by both fixed-effects and random-effects models. Heterogeneity was assessed using I² and Chi-squared tests, and publication bias was assessed by Egger’s test.

Applicability/external validity: The review highlighted that the variations in confounder adjustment strategies and differences in AMD classification criteria reduce the comparability and generalisability of the results. Additionally, the review could not account for the effects of specific intraocular lens types or surgical techniques, limiting its relevance to current cataract surgery practices. These factors should be considered when interpreting the findings in clinical contexts. The review emphasised the need for prospective, multicentre studies with well-designed RCTs to confirm these findings

Geographic focus: The review did not apply any geographical limits. The included studies were geographically diverse, originating from the United States, Australia, Germany, Israel, Denmark, the Netherlands, Switzerland, Taiwan, and Austria, reflecting a broad international representation.

Summary of quality assessment: Overall, there is low confidence in the review’s conclusions. The review authors did not specify the number of reviewers involved in the screening process, nor did it include a list of excluded studies