Interventions for diabetic macular oedema: a systematic review of the literature

Methodological quality of the review: Low confidence

Author: O’Doherty M, Dooley I, Hickey-Dwyer M.

Region: Details not provided

Sector: Diabetic macular oedema.

Sub-sector: None specified

Equity focus: None specified

Review type: Effectiveness review

Quantitative synthesis method: Narrative analysis

Qualitative synthesis methods: Not applicable

Background

Knowledge and understanding of diabetic macular oedema (DMO) which can occur at any stage of diabetic retinopathy has evolved over the past 30 years, and there now exists multiple treatment options including the use of laser and latterly the use of intravitreal injections used alone or in combination with other traditional treatments.

Research objectives

This review discussed the evolution of the treatment of diabetic macular oedema and gives helpful guidelines in the treatment of diabetic macular oedema based on available evidence to date.

Main findings

The authors identified 31 randomized control trials (RCTs) for inclusion in the systematic review which assessed the treatment of diabetic macular oedema.

Authors concluded primarily using data from one large comprehensive randomized trial and 10 other trials with smaller sample sizes that there was good evidence that laser treatment preserves vision in eyes with diabetic macular oedema (DMO). Studies showed that there is no evidence to suggest that laser type influences outcomes. However, laser treatment was associated with a number of adverse effects such as inadvertent foveal burn, central visual-field defect, colour vision abnormalities, retinal fibrosis and spread of laser scars. Authors suggested that laser surgery may be of greater benefit in combination with newer forms of treatment such as intravitreal steroid or intravitreal antiangiogenic agents.

Laser treatment remains the primary treatment for diabetic macular oedema, although recent research findings have supported the use of combination therapy.

Authors note that trials investigating the use of intravitreal corticosteroids are limited by small sample sizes and short follow-up data. Therefore although one large study had demonstrated significant efficacy with intravitreal triamcinolone, larger RCTs were needed to provide further data on long-term benefits and safety.

Methodology

Authors searched articles from MEDLINE and Cochrane database. The search was confined to randomized controlled trials in humans assessing laser treatment in diabetic macular oedema, surgery in diabetic macular oedema, the use of intravitreal triamcinolone and antivascular endothelial growth factor therapy in diabetic macular oedema; published in English only. Any additional RCTs citied in the reviews articles were also analysed.

Studies were evaluated on a standardised data extraction form for: (1) name of trial; (2) country of origin; (3) year of origin; (4) method of randomization; (5) diagnostic criteria for entry; (6) similarity of groups at baseline regarding the most important prognostic indicators; (7) clearly specified eligibility and exclusion criteria; (8) number of patients and eyes; (9) masking of outcome assessor, care provider and patient; (10) reporting of point estimates and measures of variability for outcomes; (11) intention-to-treat analysis; (12) length of follow-up; (13) adverse events; and (14) acceptable loss to follow-up rate unlikely to cause bias. The articles were then tabulated to allow easy clarification of results. Authors did not report if data extraction as well as study selection was conducted by two authors independently.

Authors conducted a narrative assessment of the data, which seemed appropriate due to the diversity and inconsistency of results of included studies.

Applicability/external validity

The authors did not address the external validity of the results, although it was clear that sample sizes (number of eyes in study) were low in most of the included studies which may have limited the review’s applicability.

Geographic focus

The geographical location of included studies is not reported.

Quality assessment

This review was attributed low confidence in the conclusions about the effects as major limitations were identified. Search strategy comprised relevant databases and reference lists in included studies restricted to published studies written only in English. Authors did not report methods used to include studies in the review and extract data of the included studies, therefore it was not possible to determine if appropriate methods were used to avoid risk of bias. Additionally, assessment of quality and risk of bias of the included studies were not reported in full.