Retinal　image　sharpness　assessment　is　one　of　the　critical　requirements　of　automatic　quality　evaluation　in　telemedicine　screening　for　diabetic　retinopathy.　In　this　paper,　a　new　sharpness　metric　measuring　the　spread　of　edges　is　presented　to　quantify　fundus　image　clarity.　After　edge　detection　on　the　region　of　interest　of　retinal　image,　the　width　of　each　edge　is　calculated　and　the　histogram　of　region　of　interest　generated.　Based　on　the　histogram,　a　distance-based　factor　is　introduced　to　gain　the　weighted　edge　width,　which　is　defined　as　the　sharpness　metric　for　the　fundus　image.　The　method　was　tested　on　Messidor　dataset　and　a　proprietary　dataset.　The　results　show　that　the　proposed　metric　performs　well　over　different　image　distortion　levels　and　resolutions　and　is　of　low　computational　complexity.　The　weighted　edge　width　value　of　gradable　retinal　image,　which　is　irrelevant　to　resolution,　is　always　within　the　range　of　3–7　pixels.　©　The　Author(s)　2017.