Comparison of different methods of retinal imaging for the screening of diabetic retinopathy: a systematic review.

BACKGROUND: Screening for diabetic retinopathy (DR) is recommended to detect sight-threatening complications prior to visual loss. Early Treatment Diabetic Retinopathy Study (ETDRS) seven standard field (7SF) retinal imaging has traditionally been regarded the gold standard for DR classification, but other methods are often preferred clinically. The purpose of this systematic review was to determine whether 7SF is the most optimal screening method for DR grading, or if similar results can be achieved by other methods using a smaller field of view (<7SF) or ultra-wide field (UWF) imaging. METHODS: Based on Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines, two independent reviewers initially identified 7167 publications in PubMed, Cochrane and Embase databases. Of these, 16 publications were included based on predefined inclusion criteria. RESULTS: 7SF was used as reference standard in 12 studies (compared with < 7SF in five studies and UWF in seven studies), and four studies compared other reference standards. Compared to 7SF, studies using < 7SF and UWF images both reported of similar agreement. A lower rate of ungradable images was reported for mydriatic and non-mydriatic UWF as compared to non-mydriatic < 7SF modalities. CONCLUSION: Retinal imaging of <7SF and UWF both provide acceptable performance compared to 7SF. Given the time-consuming nature of the latter, these methods could be reasonable options in DR screening, even though a high number of ungradable images in non-mydriatic < 7SF may pose a clinical challenge.