Intravitreal dexamethasone implant versus anti-vascular endothelial growth factor therapy combined with cataract surgery in patients with diabetic macular oedema: a systematic review with meta-analysis

Authors: Fallico M, Lotery A, Maugeri A, Favara G, Barchitta M, Agodi A, et al.

Geographical coverage: Not reported

Sector: Biomedical

Sub-sector: Treatment

Equity focus: Not reported

Study population: Patients with diabetic macular edema

Review type: Other review

Quantitative synthesis method: Meta-analysis

Qualitative synthesis method: Not applicable

Background: Cataract surgery increases the risk of diabetic retinopathy (DR) and diabetic macular edema (DME). These risks are lowered by using intravitreal anti-vascular endothelial growth factor (anti-VEGF) agents and corticosteroids with cataract surgery. Dexamethasone intravitreal implant (DEX) combined with cataract surgery has recently gained popularity. However, the later has not yet been compared with the first approach.

Objectives: To compare outcomes of cataract surgery combined with either (anti-VEGF) therapy or dexamethasone implant (DEX) in patients with diabetic macular edema (DME).

Main findings: A total of 1,417 articles were identified from the electronic database and manual reference searches, of which 19 were included in this review. Eight of the 19 included studies reported on DEX combined with cataract surgery, and 11 reported on anti-VEGF drugs combined with cataract surgery. The publication year of the included studies ranged from 2009 to 2021. The following heterogeneity sources were identified; methodological (such as, study design, mean age, follow-up length, type of anti-VEGF agent and number of injections) and clinical (for example, BCVA and CMT values at the baseline). The DEX group exhibited a significant reduction of macular thickness at three months (mean difference [MD]: -98.35 µm; 95% CI: -147.15 to -49.54), while mean CMT change was non-significant in the anti-VEGF group (MD: -21.61 µm; 95% CI: -59.46 to 16.24; test of group differences, p<0.001). At three months, no difference in visual gain was found between the two groups (p = 0.13).

The findings indicated that cataract surgery combined with DEX implant provided better anatomical outcomes in patients with DME compared with cataract surgery combined with intravitreal anti-VEGF therapy. The use of a DEX implant reduced macular thickness, while anti-VEGF therapy prevented DME from worsening. The review authors proposed further randomised trials to compare these two different combined approaches directly to confirm these results.

Methodology: Searches were conducted in PubMed and EMBASE databases to identify relevant studies. Searches were restricted to peer-reviewed articles published in the English language from inception to 28 March 2021. Reference lists of the included studies and relevant review articles were manually reviewed to identify any additional studies.

The studies conducted on patients with DME undergoing cataract surgery were included if they combined cataract surgery with intravitreal injection of anti-VEGF agent or 0.7 mg dexamethasone implant, had a follow-up of three months or longer, and reported visual and/or anatomic outcomes. Any study design apart from case report was considered.

The results were synthesised using meta-analysis. Two reviewers conducted screening and data extraction. The reviewers assessed the risk of bias of the included randomised clinical trials (RCTs) based on the Cochrane collaboration tool for RCTs, and of non-randomised studies using the methodological item for non-randomised studies (MINORS) scale. Heterogeneity was assessed using Q-statistics and I² Index. Publication bias was assessed using the funnel plot test.

Applicability/external validity: The review did not discuss the applicability or external validity of the results.

Geographic focus: The authors did not report the geographical location of included studies.

Summary of quality assessment:

The authors employed suitable techniques to consolidate data from the included studies, select studies for inclusion in the review, extract data from the selected studies and evaluate the risk of bias in these studies. However, the literature searches were not comprehensive and restricted to peer-review articles written in the English language only. Additionally, the studies with varying risk of bias were not reported and analysed separately by risk-of-bias status. For these reasons, there is low confidence in the conclusions of this review.